EFCOG Best Practice #159
Best Practice Title: Adoption of NFPA 70 2008 in place of NFPA 70 2005
Facility: DOE Complex
Point of Contact: Michael Hicks NE-ID, 208-526-3724, hicksmd@id.doe.gov
John McAlhaney SRS, 803-557-9002, jackie.mcalhaney@srs.gov
Mark McNellis SNL, 505-845-4895, msmcnel@sandia.gov
Lloyd Gordon LANL, 505-667-0778, lbgordon@lanl.gov
Brief Description of Best Practice: NFPA 70 2008 is recommended for approval across the
DOE Complex as an upgrade to NFPA 70 2005 in 10 CFR 851 Worker Safety and Health Plans
(WSHP).
Why the best practice was used: 10 CFR 851 lists safety and health consensus standards with
which the contractor must comply when applicable with site hazards (851.23). Only the versions
of consensus standards that were in effect on February 9, 2006 were promulgated pursuant to
rulemaking therefore only those specifically cited versions are required by the Rule. Contractors
may include successor versions of the consensus standards that provide equal or greater worker
protection if included in their DOE-approved worker safety and health program.
What are the benefits of the best practice: The use of NFPA 70 2008 is at least as protective
as the 2005 edition, and even more protective in some areas, such that the new edition should be
considered for DOE Complex wide acceptance. NFPA 70 2008 is recommended for approval
across the DOE Complex as an upgrade to NFPA 70 2005.
What problems/issues were associated with the best practice: There were no issues associated
with this gap analysis. Adoption of the 2008 Edition of NFPA 70 provides a level of protection
“As Safe or Safer” than the 2005 version.
How the success of the Best Practice was measured: N/A
Description of process experience using the Best Practice: At the time this analysis was
performed, process experience did not exist. .
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Change Description and Impact to
Worker Safety
Article 90
90.2 Scope.
(A) Covered. This Code covers the
installation of electrical
conductors, equipment, and raceways;
signaling and communications
conductors, equipment, and raceways;
and optical fiber cables and raceways
for the following:
(1) Public and private premises,
including buildings, structures, mobile
homes, recreational vehicles, and
floating buildings
(2) Yards, lots, parking lots, carnivals,
and industrial substations
FPN to (2): For additional information
concerning such installations in an industrial or
multibuilding complex, see ANSI C2-2002,
National Electrical Safety Code.
90.2 Scope.
(A) Covered. This Code covers the
installation of electrical conductors,
equipment, and raceways; signaling
and communications conductors,
equipment, and raceways; and
optical fiber cables and raceways for
the following:
(1) Public and private premises,
including buildings, structures, mobile
homes, recreational vehicles, and
floating buildings
(2) Yards, lots, parking lots, carnivals,
and industrial substations

(3) Installations of conductors and
equipment that connect to the supply
of electricity
(4) Installations used by the electric
utility, such as office buildings,
warehouses, garages, machine shops,
and recreational buildings, that are not
an integral part of a generating plant,
substation, or control center.
(3) Installations of conductors and
equipment that connect to the supply
of electricity
(4) Installations used by the electric
utility, such as office buildings,
warehouses, garages, machine shops,
and recreational buildings, that are not
an integral part of a generating plant,
substation, or control center.
Bonding (Bonded). The permanent
joining of metallic parts to form an
electrically conductive path that
Article 100 Definitions
Bonded (Bonding). Connected to
establish electrical continuity and
conductivity.
Page 2 of 361
Deleted fine print note referencing
ANSI C2-2002, National Electrical
Safety Code with respect to industrial
substations.
No direct safety impact.
Simplified definition.
As Safe or Safer.
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Change Description and Impact to
Worker Safety
ensures electrical continuity and the
capacity to conduct safely any current
likely to be imposed.
Device. A unit of an electrical system
that is intended to carry or control but
not utilize electric energy.
Ground. A conducting connection,
whether intentional or accidental,
between an electrical circuit or
equipment and the earth or to some
Branch-Circuit Overcurrent Device. A
device capable of providing protection
for service, feeder, and branch circuits
and equipment over the full range of
overcurrents between its rated current
and its interrupting rating. Branchcircuit overcurrent protective devices
are provided with interrupting ratings
appropriate for the intended use but no
less than 5,000 amperes.
Clothes Closet. A non-habitable room
or space intended primarily for storage
of garments and apparel.
Device. A unit of an electrical system
that carries or controls electric energy
as its principal function.
Electric Power Production and
Distribution Network. Power
production, distribution, and utilization
equipment and facilities, such as
electric utility systems that deliver
electric power to the connected loads,
that are external to and not controlled
by an interactive system.
Ground. The earth.
New definition.
As Safe or Safer.
New definition.
As Safe or Safer.
Revised definition.
As Safe or Safer.
New definition.
As Safe or Safer.
Simplified definition.
As Safe or Safer.
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conducting body that serves in place of
the earth.
Grounded. Connected to earth or to
some conducting body that serves in
place of the earth.
Grounding Conductor, Equipment. The
conductor used to connect the non–
current-carrying metal parts of
equipment, raceways, and other
enclosures to the system grounded
conductor, the grounding electrode
conductor, or both, at the service
equipment or at the source of a
separately derived system.
Grounding Electrode. A device that
establishes an electrical connection to
the earth.
Grounding Electrode Conductor. The
conductor used to connect the
grounding electrode(s) to the
equipment grounding conductor, to the
grounded conductor, or to both, at the
service, at each building or structure
where supplied by a feeder(s) or
branch circuit(s), or at the source of a
separately derived system.
2008 NEC
Change Description and Impact to
Worker Safety
Grounded (Grounding). Connected
(connecting) to ground or to a
conductive body that extends the
ground connection.
Grounding Conductor, Equipment
(EGC). The conductive path installed
to connect normally non currentcarrying metal parts of equipment
together and to the system grounded
conductor or to the grounding
electrode conductor, or both.
Simplified definition.
Grounding Electrode. A conducting
object through which a direct
connection to earth is established.
Grounding Electrode Conductor. A
conductor used to connect the system
grounded conductor or the equipment
to a grounding electrode or to a point
on the grounding electrode system.
Eliminated “device” to differentiate
from the definition of device.
As Safe or Safer.
Simplified definition removing service
and separately derived system
reference.
Intersystem Bonding Termination. A
device that provides a means for
connecting communications system(s)
New definition.
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As Safe or Safer.
Customized definition removing
service and separately derived system
reference and added fine print notes.
As Safe or Safer.
As Safe or Safer.
As Safe or Safer.
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grounding conductor(s) and bonding
conductor(s) at the service equipment
or at the disconnecting means for
buildings or structures supplied by a
feeder or branch circuit.
Kitchen. An area with a sink and
permanent facilities for food
preparation and cooking.
Luminaire. A complete lighting unit
Luminaire. A complete lighting unit
consisting of a lamp or lamps together consisting of a light source such as a
with the parts designed to distribute the lamp or lamps, together with the parts
light, to position and protect the lamps designed to position the light source
and ballast (where applicable), and to
and connect it to the power supply. It
connect the lamps to the power supply. may also include parts to protect the
light source or the ballast or to
distribute the light. A lampholder itself
is not a luminaire.
Metal-Enclosed Power Switchgear. A
Metal-Enclosed Power Switchgear. A
switchgear assembly completely
switchgear assembly completely
enclosed on all sides and top with
enclosed on all sides and top with
sheet metal (except for ventilating
sheet metal (except for ventilating
openings and inspection windows)
openings and inspection windows) and
containing primary power circuit
containing primary power circuit
switching, interrupting devices, or both, switching, interrupting devices, or both,
with buses and connections. The
with buses and connections. The
assembly may include control and
assembly may include control and
auxiliary devices. Access to the interior auxiliary devices. Access to the interior
of the enclosure is provided by doors,
of the enclosure is provided by doors,
removable covers, or both.
removable covers, or both. Metalenclosed power switchgear is available
in non-arc-resistant or arc-resistant
Page 5 of 361
Change Description and Impact to
Worker Safety
Not previously defined. Needed for
applicability of devices.
As Safe or Safer.
Enhanced definition to establish
luminaire as the complete lighting
apparatus.
As Safe or Safer.
Added “Metal-enclosed power
switchgear is available in non-arcresistant or arc-resistant
constructions.” to identify that
equipment is now available as arc
resistant.
As Safe or Safer.
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Premises Wiring (System). That
interior and exterior wiring, including
power, lighting, control, and signal
circuit wiring together with all their
associated hardware, fittings, and
wiring devices, both permanently and
temporarily installed, that extends from
the service point or source of power,
such as a battery, a solar photovoltaic
system, or a generator, transformer, or
converter windings, to the outlet(s).
Such wiring does not include wiring
internal to appliances, luminaires
(fixtures), motors, controllers, motor
control centers, and similar equipment.
Qualified Person. One who has skills
and knowledge related to the
construction and operation of the
electrical equipment and installations
2008 NEC
constructions.
Neutral Conductor. The conductor
connected to the neutral point of a
system that is intended to carry current
under normal conditions.
Neutral Point. The common point on a
wye-connection in a polyphase system
or midpoint on a single-phase, 3-wire
system, or midpoint of a single-phase
portion of a 3-phase delta system, or a
midpoint of a 3-wire, direct-current
system.
Premises Wiring (System). Interior and
exterior wiring, including power,
lighting, control, and signal circuit
wiring together with all their associated
hardware, fittings, and wiring devices,
both permanently and temporarily
installed. This includes (a) wiring from
the service point or power source to
the outlets or (b) wiring from and
including the power source to the
outlets where there is no service point.
Qualified Person. One who has skills
and knowledge related to the
construction and operation of the
electrical equipment and installations
Page 6 of 361
Change Description and Impact to
Worker Safety
New definition finally defines the
neutral conductor and calls it out
accordingly.
As Safe or Safer.
New definition.
As Safe or Safer.
Simplified definition.
As Safe or Safer.
Emphasized need to “recognize and
avoid” the hazards.
Improved safety position.
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and has received safety training on the
hazards involved.
and has received safety training to
recognize and avoid the hazards
involved.
Short-Circuit Current Rating. The
prospective symmetrical fault current at
a nominal voltage to which an
apparatus or system is able to be
connected without sustaining damage
exceeding defined acceptance criteria.
Surge Arrester. A protective device for
limiting surge voltages by discharging
or bypassing surge current; it also
prevents continued flow of follow
current while remaining capable of
repeating these functions.
Surge-Protective Device (SPD). A
protective device for limiting transient
voltages by diverting or limiting surge
current; it also prevents continued flow
of follow current while remaining
capable of repeating these functions
and is designated as follows:
Type 1: Permanently connected SPDs
intended for installation between the
secondary of the service transformer
and the line side of the service
disconnect overcurrent device.
Type 2: Permanently connected SPDs
intended for installation on the load
side of the service disconnect
overcurrent device, including SPDs
Page 7 of 361
Change Description and Impact to
Worker Safety
New definition to accommodate new
requirements in other articles.
As Safe or Safer.
New definition to accommodate wider
use of surge arresters.
As Safe or Safer.
New definition to accommodate wider
use of surge protective devices.
As Safe or Safer.
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located at the branch panel.
Type 3: Point of utilization SPDs.
Type 4: Component SPDs, including
discrete components, as well as
assemblies.
Ungrounded. Not connected to ground
or to a conductive body that extends
the ground connection.
Utility-Interactive Inverter. An inverter
intended for use in parallel with an
electric utility to supply common loads
that may deliver power to the utility.
Article 110
110.7 Insulation Integrity. Completed
110.7 Wiring Integrity. Completed
wiring installations shall be free from
wiring installations shall be free from
short circuits and from grounds other
short circuits, ground faults, or any
than as required or permitted in Article connections to ground other than as
250.
required or permitted elsewhere in this
Code.
110.12 Mechanical Execution of Work. 110.12 Mechanical Execution of Work.
(A) Unused Openings. Unused cable
(A) Unused Openings. Unused
or raceway openings in boxes,
openings, other than those intended for
raceways, auxiliary gutters, cabinets,
the operation of equipment, those
cutout boxes, meter socket enclosures, intended for mounting purposes, or
equipment cases, or housings shall be those permitted as part of the design
effectively closed to afford protection
for listed equipment, shall be closed to
substantially equivalent to the wall of
afford protection substantially
the equipment. Where metallic plugs or equivalent to the wall of the equipment.
plates are used with nonmetallic
Where metallic plugs or plates are
enclosures, they shall be recessed at
used with nonmetallic enclosures, they
least 6 mm (1⁄4 in.) from the outer
shall be recessed at least 6 mm (1⁄4
Page 8 of 361
Change Description and Impact to
Worker Safety
New definition to accommodate use of
ungrounded parts in other articles.
As Safe or Safer.
New definition to accommodate wider
use of this equipment type.
As Safe or Safer.
Changed to comply with NEC Style
Manual and better address the
possibilities in more than one article.
As Safe or Safer.
Improved readability.
As Safe or Safer.
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in.) from the outer surface of the
enclosure.
110.16 Flash Protection. Switchboards, 110.16 Flash Protection. Electrical
panelboards, industrial control panels, equipment, such as switchboards,
meter socket enclosures, and motor
panelboards, industrial control panels,
control centers that are in other than
meter socket enclosures, and motor
dwelling occupancies and are likely to
control centers, that are in other than
require examination, adjustment,
dwelling occupancies, and are likely to
servicing, or maintenance while
require examination, adjustment,
energized shall be field marked to warn servicing, or maintenance while
qualified persons of potential electric
energized shall be field marked to warn
arc flash hazards. The marking shall
qualified persons of potential electric
be located so as to be clearly visible to arc flash hazards. The marking shall
qualified persons before examination,
be located so as to be clearly visible to
adjustment, servicing, or maintenance qualified persons before
of the equipment.
examination, adjustment, servicing, or
maintenance of the equipment.
110.20 Enclosure Types. Enclosures
(other than surrounding fences or
walls) of switchboards, panelboards,
industrial control panels, motor control
centers, meter sockets, and motor
controllers, rated not over 600 volts
nominal and intended for such
locations, shall be marked with an
enclosure-type number as shown in
Table 110.20.
Table 110.20 shall be used for
selecting these enclosures for use in
specific locations other than hazardous
(classified) locations. The enclosures
Change Description and Impact to
Worker Safety
surface of the enclosure.
Page 9 of 361
Clarifies that equipment similar to the
types mentioned are also subject to
the requirement.
No impact since we already included
similar equipment in our evaluations.
New section covering enclosure types
and the NEMA designation applicability
moved from 430.91. Table 430.91 was
also moved to make it clear which
enclosure type is needed for the
environment in which it will be
operated and that it applies to more
than motor controllers.
As Safe or Safer.
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are not intended to protect against
conditions such as condensation, icing,
corrosion, or contamination that may
occur within the enclosure or enter via
the conduit or unsealed openings.
110.22 Identification of Disconnecting
Means.
(B) Engineered Series Combination
Systems. Where circuit breakers or
fuses are applied in compliance with
series combination ratings selected
under engineering supervision and
marked on the equipment as directed
by the engineer, the equipment
enclosure(s) shall be legibly marked in
the field to indicate the equipment has
been applied with a series combination
rating. The marking shall be readily
visible and state the following:
110.26 (C) Entrance to Working
Space.
(1) Minimum Required. At least one
entrance of sufficient area shall be
provided to give access to working
space about electrical equipment.
CAUTION — ENGINEERED SERIES
COMBINATION SYSTEM RATED
_______ AMPERES. IDENTIFIED
REPLACEMENT COMPONENTS
REQUIRED.
110.26 (C) Entrance to and Egress
from Working Space.
(1) Minimum Required. At least one
entrance of sufficient area shall be
provided to give access to and egress
from working space about electrical
Page 10 of 361
Change Description and Impact to
Worker Safety
New section to identify series
combination ratings by engineering
and the associated marking
requirements.
As Safe or Safer.
Added egress wording for clarification
that personnel egress is the important
item here.
As Safe or Safer.
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110.26 (C) Entrance to Working
Space.
2008 NEC
Change Description and Impact to
Worker Safety
equipment.
110.26 (C) Entrance to and Egress
from Working Space.
The change makes this requirement
only applicable to rooms with
equipment over 1.8 m wide reducing
(2) Large Equipment. For equipment
(2) Large Equipment. For equipment
the somewhat over burdensome
rated 1200 amperes or more that
rated 1200 amperes or more and over requirement when the equipment does
contains overcurrent devices, switching 1.8 m (6 ft) wide that contains
not pose a threat to worker egress.
devices, or control devices, there shall overcurrent devices, switching devices, Wording changed to be consistent with
be one entrance to the required
or control devices, there shall be one
life safety terminology.
working space not less than 610 mm
entrance to and egress from the
(24 in.) wide and 2.0 m (61⁄2 ft) high at required working space not less than
As Safe or Safer.
each end of the working space.
610 mm (24 in.) wide and 2.0 m (61⁄2
Where the entrance has a personnel
ft) high at each end of the working
door(s), the door(s) shall open in the
space. A single entrance to and egress
direction of egress and be equipped
from the required working space shall
with panic bars, pressure plates, or
be permitted where either of the
other devices that are normally latched conditions in 110.26(C)(2)(a) or
but open under simple pressure. A
(C)(2)(b) is met.
single entrance to the required working
space shall be permitted where either
of the conditions in 110.26(C)(2)(a) or
(C)(2)(b) is met.
(a) Unobstructed Exit. Where the
location permits a continuous and
unobstructed way of exit travel, a
single entrance to the working space
shall be permitted.
(a) Unobstructed Egress. Where the
location permits a continuous and
unobstructed way of egress travel, a
single entrance to the working space
shall be permitted.
110.26(C)(3) Personnel Doors. Where New section extracted from (C)(2) and
equipment rated 1200 A or more that
added here to address the situation of
contains overcurrent devices, switching egress during an arc flash or similar
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110.33 Entrance and Access to Work
Space.
(A) Entrance. At least one entrance not
less than 610 mm (24 in.) wide and 2.0
m (61⁄2 ft) high shall be provided to
give access to the working space
about electric equipment. Where the
entrance has a personnel door(s), the
door(s) shall open in the direction of
egress and be equipped with panic
bars, pressure plates, or other devices
that are normally latched but open
under simple pressure.
2008 NEC
devices, or control devices is installed
and there is a personnel door(s)
intended for entrance to and egress
from the working space less than 7.6 m
(25 ft) from the nearest edge of the
working space, the door(s) shall open
in the direction of egress and be
equipped with panic bars, pressure
plates, or other devices that are
normally latched but open under
simple pressure.
110.26(G) Locked Electrical Equipment
Rooms or Enclosures.
Electrical equipment rooms or
enclosures housing electrical
apparatus that are controlled by a
lock(s) shall be considered accessible
to qualified persons.
110.33 Entrance to Enclosures and
Access to Working Space.
(A) Entrance. At least one entrance to
enclosures for electrical installations as
described in 110.31 not less than 610
mm (24 in.) wide and 2.0 m (61⁄2 ft)
high shall be provided to give access
to the working space about electrical
equipment.
Page 12 of 361
Change Description and Impact to
Worker Safety
event.
Actually provides added worker safety.
New section to clarify that locked doors
do not constitute inaccessibility to
qualified persons.
As Safe or Safer.
Revised to move information into new
section 110.33(A)(3) and to clarify just
where the requirement applies.
As Safe or Safer.
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110.34 Work Space and Guarding.
(A) Working Space. Except as
elsewhere required or permitted in this
Code, the minimum clear working
space in the direction of access to live
parts of electrical equipment shall not
be less than specified in Table
110.34(A). Distances shall be
measured from the live parts, if such
are exposed, or from the enclosure
front or opening if such are enclosed.
110.33 (A)(3) Personnel Doors. Where
there is a personnel door(s) intended
for entrance to and egress from the
working space less than 7.6 m (25 ft)
from the nearest edge of the working
space, the door(s) shall open in the
direction of egress and be equipped
with panic bars, pressure plates, or
other devices that are normally latched
but open under simple pressure.
110.34 Work Space and Guarding.
(A) Working Space. Except as
elsewhere required or permitted in this
Code, equipment likely to require
examination, adjustment, servicing, or
maintenance while energized shall
have clear working space in the
direction of access to live parts of the
electrical equipment and shall be not
less than specified in Table 110.34(A).
Distances shall be measured from the
live parts, if such are exposed, or from
the enclosure front or opening if such
are enclosed.
Article 200
200.2 General. All premises wiring
systems, other than circuits and
systems exempted or prohibited by
210.10, 215.7, 250.21, 250.22,
250.162, 503.155, 517.63, 668.11,
668.21, and 690.41, Exception, shall
200.2 General. All premises wiring
systems, other than circuits and
systems exempted or prohibited by
210.10, 215.7, 250.21, 250.22,
250.162, 503.155, 517.63, 668.11,
668.21, and 690.41 Exception, shall
Page 13 of 361
Change Description and Impact to
Worker Safety
New section with information relocated
from main section 110.33(A).
As Safe or Safer.
Added “equipment likely to require
examination, adjustment, servicing, or
maintenance while energized” to
address only the equipment required to
have working space.
As Safe or Safer.
Shortened original section and refers
to two new sections with information
from the original section.
As Safe or Safer.
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have a grounded conductor that is
identified in accordance with 200.6.
The grounded conductor, where
insulated, shall have insulation that is
(1) suitable, other than color, for any
ungrounded conductor of the same
circuit on circuits of less than 1000
volts or impedance grounded neutral
systems of 1 kV and over, or (2) rated
not less than 600 volts for solidly
grounded neutral systems of 1 kV and
over as described in 250.184(A).
2008 NEC
Change Description and Impact to
Worker Safety
have a grounded conductor that is
identified in accordance with 200.6.
The grounded conductor shall comply
with 200.2(A) and (B).
200.2(A) Insulation. The grounded
conductor, where insulated, shall have
insulation that is (1) suitable, other
than color, for any ungrounded
conductor of the same circuit on
circuits of less than 1000 volts or
impedance grounded neutral systems
of 1 kV and over, or (2) rated not less
than 600 volts for solidly grounded
neutral systems of 1 kV and over as
described in 250.184(A).
200.2(B) Continuity. The continuity of a
grounded conductor shall not depend
on a connection to a metallic
enclosure, raceway, or cable armor.
200.3 Connection to Grounded
System.
Exception: Listed utility-interactive
Page 14 of 361
Relocated and renamed from original.
As Safe or Safer.
New section improving ground
continuity.
As Safe or Safer.
New exception added to address
increased use of photovoltaic
equipment and fuel cells.
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inverters identified for use in distributed
resource generation systems such as
photovoltaic and fuel cell power
systems shall be permitted to be
connected to premises wiring without a
grounded conductor where the
connected premises wiring or utility
system includes a grounded conductor.
Article 210
210.4 Multiwire Branch Circuits.
210.4 Multiwire Branch Circuits.
(A) General. Branch circuits
(A) General. Branch circuits
recognized by this article shall be
recognized by this article shall be
permitted as multiwire circuits. A
permitted as multiwire circuits. A
multiwire circuit shall be permitted to
multiwire circuit shall be permitted to
be considered as multiple circuits. All
be considered as multiple circuits. All
conductors shall originate from the
conductors of a multiwire branch circuit
same panelboard or similar distribution shall originate from the same
equipment.
panelboard or similar distribution
equipment.
210.4(B) Devices or Equipment. Where 210.4(B) Disconnecting Means. Each
a multiwire branch circuit supplies
multiwire branch circuit shall be
more than one device or equipment on provided with a means that will
the same yoke, a means shall be
simultaneously disconnect all
provided to disconnect simultaneously ungrounded conductors at the point
all ungrounded conductors supplying
where the branch circuit originates.
those devices or equipment at the
point where the branch circuit
originates.
210.4(D) Grouping. The ungrounded
and grounded conductors of each
multiwire branch circuit shall be
Page 15 of 361
Change Description and Impact to
Worker Safety
As Safe or Safer.
Clarification of conductors in a
multiwire branch circuit.
As Safe or Safer.
Clarification, that actually will help
reduce the common neutral situation
even more than previous Code
improvements.
New section that imposes
requirements that will also assist in
reducing the risk of common neutral
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210.5 Identification for Branch Circuits.
(C) Ungrounded Conductors. Where
the premises wiring system has branch
circuits supplied from more than one
nominal voltage system, each
ungrounded conductor of a branch
circuit, where accessible, shall be
identified by system. The means of
identification shall be permitted to be
by separate color coding, marking
tape, tagging, or other approved
means and shall be permanently
posted at each branch-circuit
panelboard or similar branch-circuit
distribution equipment.
2008 NEC
grouped by wire ties or similar means
in at least one location within the
panelboard or other point of
origination.
Exception: The requirement for
grouping shall not apply if the circuit
enters from a cable or raceway unique
to the circuit that makes the grouping
obvious.
210.5 Identification for Branch Circuits.
(C) Ungrounded Conductors. Where
the premises wiring system has branch
circuits supplied from more than one
nominal voltage system, each
ungrounded conductor of a branch
circuit shall be identified by phase or
line and system at all termination,
connection, and splice points. The
means of identification shall be
permitted to be by separate color
coding, marking tape, tagging, or other
approved means. The method utilized
for conductors originating within each
branch circuit panelboard or similar
branch circuit distribution equipment
shall be documented in a manner that
is readily available or shall be
permanently posted at each branch
circuit panelboard or similar branch
circuit distribution equipment.
210.6 Branch-Circuit Voltage
Page 16 of 361
Change Description and Impact to
Worker Safety
encounters.
Clarifies identification requirements for
branch circuits to include any point
where there is a connection and it now
requires documentation.
Improves worker safety.
New section adding luminaires to the
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Limitations.
(D) 600 Volts Between Conductors.
(3) Luminaires powered from directcurrent systems where the luminaire
contains a listed, dc-rated ballast that
provides isolation between the dc
power source and the lamp circuit and
protection from electric shock when
changing lamps.
210.8 Ground-Fault Circuit-Interrupter
210.8 Ground-Fault Circuit-Interrupter
Protection for Personnel.
Protection for Personnel.
(B) Other Than Dwelling Units. All 125- (B) Other Than Dwelling Units. All 125volt, single phase, 15- and 20-ampere
volt, single phase, 15- and 20-ampere
receptacles installed in the locations
receptacles installed in the locations
specified in (1) through (5) shall have
specified in (1) through (5) shall have
ground-fault circuit-interrupter
ground-fault circuit-interrupter
protection for personnel:
protection for personnel:
(1) Bathrooms
(1) Bathrooms
(2) Commercial and institutional
(2) Kitchens
kitchens—for the purposes of this
(3) Rooftops
section, a kitchen is an area with a sink (4) Outdoors
and permanent facilities for food
preparation and cooking
Exception No. 2 to (4): In industrial
(3) Rooftops
establishments only, where the
(4) Outdoors in public spaces—for the conditions of maintenance and
purpose of this section a public space
supervision ensure that only qualified
is defined as any space that is for
personnel are involved, an assured
use by, or is accessible to, the public
equipment grounding conductor
program as specified in 590.6(B)(2)
Exception to (3) and (4): Receptacles
shall be permitted for only those
that are not readily accessible and are receptacle outlets used to supply
Page 17 of 361
Change Description and Impact to
Worker Safety
types of equipment allowed to be fed
from circuits over 277 volts but less
than 600 volts.
As Safe or Safer.
Simplified by moving the definition of
kitchen to Article 100 and removing the
caveats about outdoors in public
spaces as well as adding sinks as a
specific location. Exceptions were
added to eliminate the requirement in
areas that would not benefit from GFCI
installation.
As Safe or Safer.
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supplied from a dedicated branch
circuit for electric snow-melting or
deicing equipment shall be permitted to
be installed in accordance with the
applicable provisions of Article 426.
equipment that would create a greater
hazard if power is interrupted or having
a design that is not compatible with
GFCI protection.
Change Description and Impact to
Worker Safety
(5) Sinks — where receptacles are
(5) Outdoors, where installed to comply installed within 1.8 m (6 ft) of the
with 210.63
outside edge of the sink.
Exception No 1 to (5): In industrial
laboratories, receptacles used to
supply equipment where removal of
power would introduce a greater
hazard shall be permitted to be
installed without GFCI protection.
Exception No 2 to (5): For receptacles
located in patient care areas of health
care facilities other than those covered
under 210.8(B)(1), GFCI protection
shall not be required.
II. Branch-Circuit Ratings
210.19 Conductors — Minimum
Ampacity and Size.
(A) Branch Circuits Not More Than 600
Volts.
(1) General
Exception No. 2: Grounded conductors
that are not connected to an
overcurrent device shall be permitted
Page 18 of 361
New exception added to allow the
grounded conductor (neutral) to be
sized at 100% vs. 125%.
As Safe or Safer.
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to be sized at 100 percent of the
continuous and noncontinuous load.
Article 215
215.2 Minimum Rating and Size.
(A) Feeders Not More Than 600 Volts.
(1) General.
Exception No. 2: Grounded conductors
that are not connected to an
overcurrent device shall be permitted
to be sized at 100 percent of the
continuous and noncontinuous load.
215.6 Feeder Conductor Grounding
215.6 Feeder Equipment Grounding
Means. Where a feeder supplies
Conductor. Where a feeder supplies
branch circuits in which equipment
branch circuits in which equipment
grounding conductors are required, the grounding conductors are required, the
feeder shall include or provide a
feeder shall include or provide an
grounding means, in accordance with
equipment grounding conductor in
the provisions of 250.134, to which the accordance with the provisions of
equipment grounding conductors of the 250.134, to which the equipment
branch circuits shall be connected.
grounding conductors of the branch
circuits shall be connected. Where the
feeder supplies a separate building or
structure, the requirements of
250.32(B) shall apply.
215.12 Identification for Feeders.
215.12 Identification for Feeders.
(C) Ungrounded Conductors. Where
(C) Ungrounded Conductors. Where
the premises wiring system has
the premises wiring system has
feeders supplied from more than one
feeders supplied from more than one
nominal voltage system, each
nominal voltage system, each
ungrounded conductor of a feeder,
ungrounded conductor of a feeder shall
Page 19 of 361
Change Description and Impact to
Worker Safety
New exception added to allow the
grounded conductor (neutral) to be
sized at 100% vs. 125%.
As Safe or Safer.
Modified section to address the term
equipment grounding conductor with
respect to feeder installations as well
as address feeders supplying
buildings.
As Safe or Safer.
Clarifies identification requirements for
feeder circuits to include any point
where there is a connection and it now
requires documentation.
Improves worker safety.
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where accessible, shall be identified by
system. The means of identification
shall be permitted to be by separate
color coding, marking tape, tagging, or
other approved means and shall be
permanently posted at each feeder
panelboard or similar feeder
distribution equipment.
225.39 Rating of Disconnect. The
feeder or branch-circuit disconnecting
means shall have a rating of not less
than the load to be supplied,
determined in accordance with Parts I
and II of Article 220 for branch circuits,
Parts III or IV of Article 220 for feeders,
or Part V of Article 220 for farm loads.
In no case shall the rating be lower
than specified in 225.39(A), (B), (C), or
(D).
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Change Description and Impact to
Worker Safety
be identified by phase or line and
system at all termination, connection,
and splice points. The means of
identification shall be permitted to be
by separate color coding, marking
tape, tagging, or other approved
means. The method utilized for
conductors originating within each
feeder panelboard or similar feeder
distribution equipment shall be
documented in a manner that is readily
available or shall be permanently
posted at each feeder panelboard or
similar feeder distribution equipment.
Article 225
225.39 Rating of Disconnect. The
Provides alternate method for
feeder or branch-circuit disconnecting
determining rating.
means shall have a rating of not less
than the calculated load to be supplied, As Safe or Safer.
determined in accordance with Parts I
and II of Article 220 for branch circuits,
Part III or IV of Article 220 for feeders,
or Part V of Article 220 for farm loads.
Where the branch circuit or feeder
disconnecting means consists of more
than one switch or circuit breaker, as
permitted by 225.33, combining the
ratings of all the switches or circuit
breakers for determining the rating of
the disconnecting means shall be
permitted. In no case shall the rating
Page 20 of 361
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be lower than specified in 225.39(A),
(B), (C), or (D).
Article 230
230.42 Minimum Size and Rating.
230.42 Minimum Size and Rating.
(A) General. The ampacity of the
(A) General. The ampacity of the
service-entrance conductors before the service-entrance conductors before the
application of any adjustment or
application of any adjustment or
correction factors shall not be less than correction factors shall not be less than
either (A)(1) or (A)(2). Loads shall be
either (A)(1) or (A)(2). Loads shall be
determined in accordance with Article
determined in accordance with Part III,
220. Ampacity shall be determined
IV, or V of Article 220, as applicable.
from 310.15. The maximum allowable
Ampacity shall be determined from
current of busways shall be that value
310.15. The maximum allowable
for which the busway has been listed
current of busways shall be that value
or labeled.
for which the busway has been listed
or labeled.
230.44 Cable Trays.
230.44 Cable Trays.
Exception: Conductors other than
Exception: Conductors, other than
service-entrance conductors shall be
service-entrance conductors, shall be
permitted to be installed in a cable tray permitted to be installed in a cable tray
with service-entrance conductors,
with service-entrance conductors,
provided a solid fixed barrier of a
provided a solid fixed barrier of a
material compatible with the cable tray material compatible with the cable tray
is installed to separate the serviceis installed to separate the serviceentrance conductors from other
entrance conductors from other
conductors installed in the cable tray.
conductors installed in the cable tray.
Cable trays shall be identified with
permanently affıxed labels with the
wording “Service-Entrance
Conductors.” The labels shall be
located so as to be visible after
Page 21 of 361
Change Description and Impact to
Worker Safety
Clarifies the intent of applicable parts
of Article 220.
As Safe or Safer.
Added identification requirements for
service-entrance conductors.
As Safe or Safer.
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installation and placed so that the
service-entrance conductors may be
readily traced through the entire length
of the cable tray.
230.50 Protection of Open Conductors 230.50 Protection Against Physical
and Cables Against Damage — Above Damage.
Ground. Service-entrance conductors
(A) Underground Service-Entrance
installed above ground shall be
Conductors. Underground serviceprotected against physical damage as
entrance conductors shall be protected
specified in 230.50(A) or (B).
against physical damage in
accordance with 300.5.
(B) All Other Service-Entrance
Conductors. All other service-entrance
conductors, other than underground
service entrance conductors, shall be
protected against physical damage as
specified in 230.50(B)(1) or (B)(2).
230.53 Raceways to Drain. Where
230.53 Raceways to Drain. Where
exposed to the weather, raceways
exposed to the weather, raceways
enclosing service-entrance conductors enclosing service-entrance conductors
shall be raintight and arranged to drain. shall be suitable for use in wet
Where embedded in masonry,
locations and arranged to drain. Where
raceways shall be arranged to drain.
embedded in masonry, raceways shall
be arranged to drain.
Exception: As permitted in 348.12(1).
230.54 Overhead Service Locations.
230.54 Overhead Service Locations.
(A) Raintight Service Head. Service
(A) Service Head. Service raceways
raceways shall be equipped with a
shall be equipped with a service head
raintight service head at the point of
at the point of connection to service
connection to service-drop conductors. drop conductors. The service head
shall comply with the requirement for
Page 22 of 361
Change Description and Impact to
Worker Safety
Modified to address specific
requirements for underground service
entrance conductors and impose the
same requirements for installation as
other underground conductors.
As Safe or Safer.
Clarified to address broader
requirements of wet locations and
eliminated the exception.
As Safe or Safer.
Eliminated “raintight” to be consistent
with terminology used for wet
locations. Added location of
requirements for the service head.
As Safe or Safer.
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(B) Service Cable Equipped with
Raintight Service Head or Gooseneck.
Service cables shall be equipped with
a raintight service head.
230.71 Maximum Number of
Disconnects.
(A) General.
For the purpose of this section,
disconnecting means used solely for
power monitoring equipment, transient
voltage surge suppressors, or the
control circuit of the ground-fault
protection system or power-operable
service disconnecting means, installed
as part of the listed equipment, shall
not be considered a service
disconnecting means.
230.79 Rating of Service
Disconnecting Means. The service
disconnecting means shall have a
rating not less than the load to be
carried, determined in accordance with
Article 220. In no case shall the rating
be lower than specified in 230.79(A),
(B), (C), or (D).
2008 NEC
fittings in 314.15.
(B) Service Cable Equipped with
Service Head or Gooseneck. Service
cables shall be equipped with a service
head. The service head shall comply
with the requirement for fittings in
314.15.
230.71 Maximum Number of
Disconnects.
(A) General.
For the purpose of this section,
disconnecting means installed as part
of listed equipment and used solely for
the following shall not be considered a
service disconnecting means:
(1) Power monitoring equipment
(2) Surge-protective device(s)
(3) Control circuit of the ground-fault
protection system
(4) Power-operable service
disconnecting means
230.79 Rating of Service
Disconnecting Means. The service
disconnecting means shall have a
rating not less than the calculated load
to be carried, determined in
accordance with Part III, IV, or V of
Article 220, as applicable. In no case
shall the rating be lower than specified
in 230.79(A), (B), (C), or (D).
Page 23 of 361
Change Description and Impact to
Worker Safety
Eliminated “raintight” to be consistent
with terminology used for wet
locations. Added location of
requirements for the service head.
As Safe or Safer.
Clarified the intent that when installed
as part of listed equipment and used
for the specific items the disconnecting
means is not service disconnect.
As Safe or Safer.
Clarifies the intent of applicable parts
of Article 220.
As Safe or Safer.
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230.82 Equipment Connected to the
Supply Side of Service Disconnect.
Only the following equipment shall be
permitted to be connected to the
supply side of the service
disconnecting means:
(1) Cable limiters or other currentlimiting devices
(2) Meters and meter sockets
nominally rated not in excess of 600
volts, provided all metal housings and
service enclosures are grounded
(3) Meter disconnect switches
nominally rated not in excess of 600
volts that have a short-circuit current
rating equal to or greater than the
available short circuit current, provided
all metal housings and service
enclosures are grounded
(4) Instrument transformers (current
and voltage), impedance shunts, load
management devices, and arresters
230.82 Equipment Connected to the
Supply Side of Service Disconnect.
Only the following equipment shall be
permitted to be connected to the
supply side of the service
disconnecting means:
(1) Cable limiters or other currentlimiting devices.
(2) Meters and meter sockets
nominally rated not in excess of 600
volts, provided all metal housings and
service enclosures are grounded in
accordance with Part VII and bonded
in accordance with Part V of Article
250.
(3) Meter disconnect switches
nominally rated not in excess
of 600 volts that have a short-circuit
current rating equal to or greater than
the available short-circuit current,
provided all metal housings and
service enclosures are grounded in
accordance with Part VII and bonded
in accordance with Part V of Article
250. A meter disconnect switch shall
be capable of interrupting the load
served.
(4) Instrument transformers (current
and voltage), impedance shunts, load
management devices, surge arresters,
and Type 1 surge-protective devices.
(8) Ground-fault protection systems or
transient voltage surge suppressors,
where installed as part of listed
equipment, if suitable overcurrent
protection and disconnecting means
are provided
Page 24 of 361
Change Description and Impact to
Worker Safety
Adds specific reference to the
requirements for grounding and
clarifies arrester types.
As Safe or Safer.
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230.95 Ground-Fault Protection of
Equipment. Ground fault protection of
equipment shall be provided for solidly
grounded wye electrical services of
more than 150 volts to ground but not
exceeding 600 volts phase-to-phase
for each service disconnect rated 1000
amperes or more. The grounded
conductor for the solidly grounded wye
system shall be connected directly to
ground without inserting any resistor or
impedance device.
The rating of the service disconnect
shall be considered to be the rating of
the largest fuse that can be installed or
the highest continuous current trip
setting for which the actual overcurrent
device installed in a circuit breaker is
rated or can be adjusted.
Exception No. 1: The ground-fault
protection provisions of this section
shall not apply to a service disconnect
for a continuous industrial process
where a nonorderly shutdown will
2008 NEC
(8) Ground-fault protection systems or
Type 2 surge protective devices, where
installed as part of listed equipment, if
suitable overcurrent protection and
disconnecting means are provided.
230.95 Ground-Fault Protection of
Equipment. Ground fault protection of
equipment shall be provided for solidly
grounded wye electric services of more
than 150 volts to ground but not
exceeding 600 volts phase-to-phase
for each service disconnect rated 1000
amperes or more. The grounded
conductor for the solidly grounded wye
system shall be connected directly to
ground through a grounding electrode
system, as specified in 250.50, without
inserting any resistor or impedance
device.
Exception: The ground-fault protection
provisions of this section shall not
apply to a service disconnect for a
continuous industrial process where a
nonorderly shutdown will introduce
additional or increased hazards.
Page 25 of 361
Change Description and Impact to
Worker Safety
Specifies the grounding requirements
to remove any doubts. Removed
exception for fire pumps.
As Safe or Safer.
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Change Description and Impact to
Worker Safety
introduce additional or increased
hazards.
Exception No. 2: The ground-fault
protection provisions of this section
shall not apply to fire pumps.
230.204 Isolating Switches.
(D) Grounding Connection. Isolating
switches shall be provided with a
means for readily connecting the load
side conductors to ground when
disconnected from the source of
supply.
A means for grounding the load side
conductors shall not be required for
any duplicate isolating switch installed
and maintained by the electric supply
company.
230.205 Disconnecting Means.
(A) Location. The service
disconnecting means shall be located
in accordance with 230.70.
230.204 Isolating Switches.
(D) Connection to Ground. Isolating
switches shall be provided with a
means for readily connecting the load
side conductors to a grounding
electrode system, equipment ground
busbar, or grounded steel structure
when disconnected from the source of
supply.
A means for grounding the load side
conductors to a grounding electrode
system, equipment grounding busbar,
or grounded structural steel shall not
be required for any duplicate isolating
switch installed and maintained by the
electric supply company.
230.205 Disconnecting Means.
(A) Location. The service
disconnecting means shall be located
in accordance with 230.70.
For either overhead or underground
primary distribution systems on private
property, the service disconnect shall
be permitted to be located in a location
that is not readily accessible.
Page 26 of 361
Specifies the grounding requirements
to remove any doubts.
As Safe or Safer.
Allows private property owners some
relief.
As Safe or Safer.
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Change Description and Impact to
Worker Safety
Article 240
240.4 Protection of Conductors.
240.4 Protection of Conductors.
Provides specific criteria for
(D) Small Conductors. Unless
(D) Small Conductors. Unless
conductors smaller than 14 AWG.
specifically permitted in 240.4(E) or
specifically permitted in 240.4(E) or
240.4(G), the overcurrent protection
(G), the overcurrent protection shall not As Safe or Safer.
shall not exceed 15 amperes for 14
exceed that required by (D)(1) through
AWG, 20 amperes for 12 AWG, and 30 (D)(7) after any correction factors for
amperes for 10 AWG copper; or 15
ambient temperature and number of
amperes for 12 AWG and 25 amperes conductors have been applied.
for 10 AWG aluminum and copper-clad (1) 18 AWG Copper. 7 amperes,
aluminum after any correction factors
provided all the following conditions
for ambient temperature and number of are met:
conductors have been applied.
(1) Continuous loads do not exceed
5.6 amperes.
(2) Overcurrent protection is provided
by one of the following:
a. Branch-circuit-rated circuit
breakers listed and marked for use
with 18 AWG copper wire
b. Branch-circuit-rated fuses listed
and marked for use with 18 AWG
copper wire
c. Class CC, Class J, or Class T
fuses
(2) 16 AWG Copper. 10 amperes,
provided all the following conditions
are met:
(1) Continuous loads do not exceed 8
amperes.
(2) Overcurrent protection is provided
by one of the following:
Page 27 of 361
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240.5 Protection of Flexible Cords,
Flexible Cables, and Fixture Wires.
(B) Branch Circuit Overcurrent Device.
Flexible cord shall be protected where
supplied by a branch circuit in
accordance with one of the methods
described in 240.5(B)(1), (B)(2), (B)(3),
or (B)(4).
(1) Supply Cord of Listed Appliance or
Portable Lamps. Where flexible cord or
tinsel cord is approved for and used
with a specific listed appliance or
portable lamp, it shall be considered to
2008 NEC
a. Branch-circuit-rated circuit
breakers listed and marked for use
with 16 AWG copper wire
b. Branch-circuit-rated fuses listed
and marked for use with 16 AWG
copper wire
c. Class CC, Class J, or Class T
fuses
(3) 14 AWG Copper. 15 amperes
(4) 12 AWG Aluminum and CopperClad Aluminum. 15 amperes
(5) 12 AWG Copper. 20 amperes
(6) 10 AWG Aluminum and CopperClad Aluminum. 25 amperes
(7) 10 AWG Copper. 30 amperes
240.5 Protection of Flexible Cords,
Flexible Cables, and Fixture Wires.
(B) Branch-Circuit Overcurrent Device.
Flexible cord shall be protected, where
supplied by a branch circuit, in
accordance with one of the methods
described in 240.5(B)(1), (B)(3), or
(B)(4). Fixture wire shall be protected,
where supplied by a branch circuit, in
accordance with 240.5(B)(2).
(1) Supply Cord of Listed Appliance or
Luminaire.
Where flexible cord or tinsel cord is
approved for and used with a specific
listed appliance or luminaire, it shall be
Page 28 of 361
Change Description and Impact to
Worker Safety
Provides specific requirements for
protection of fixture wire.
As Safe or Safer.
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considered to be protected when
applied within the appliance or
luminaire listing requirements. For the
purposes of this section, a luminaire
may be either portable or permanent.
240.21 Location in Circuit.
240.21 Location in Circuit.
(C) Transformer Secondary
(C) Transformer Secondary
Conductors. Each set of conductors
Conductors. A set of conductors
feeding separate loads shall be
feeding a single load, or each set of
permitted to be connected to a
conductors feeding separate loads,
transformer secondary, without
shall be permitted to be connected to a
overcurrent protection at the
transformer secondary, without
secondary, as specified in
overcurrent protection at the
240.21(C)(1) through (C)(6). The
secondary, as specified in
provisions of 240.4(B) shall not be
240.21(C)(1) through (C)(6). The
permitted for transformer secondary
provisions of 240.4(B) shall not be
conductors.
permitted for transformer secondary
conductors.
240.21 Location in Circuit.
240.21 Location in Circuit.
(C) Transformer Secondary
(C) Transformer Secondary
Conductors.
Conductors.
(2) Transformer Secondary Conductors (2) Transformer Secondary Conductors
Not Over 3 m (10 ft) Long.
Not Over 3 m (10 ft) Long. (4) For field
installations where the secondary
conductors leave the enclosure or vault
in which the supply connection is
made, the rating of the overcurrent
device protecting the primary of the
transformer, multiplied by the primary
to secondary transformer voltage ratio,
shall not exceed 10 times the ampacity
Change Description and Impact to
Worker Safety
be protected when applied within the
appliance or portable lamp listing
requirements.
Page 29 of 361
Clarified intent to address single loads
as well as multiple load arrangements.
As Safe or Safer.
New section to address situations
where the primary device rating may
be too high to adequately protect the
tap conductors.
As Safe or Safer.
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240.21 Location in Circuit.
(C) Transformer Secondary
Conductors.
(3) Industrial Installation Secondary
Conductors Not Over 7.5 m (25 ft)
Long. For industrial installations only,
where the length of the secondary
conductors does not exceed 7.5 m (25
ft) and complies with all of the
following:
240.21 Location in Circuit.
240.24 Location in or on Premises.
(B) Occupancy. Each occupant shall
have ready access to all overcurrent
devices protecting the conductors
supplying that occupancy.
Exception No. 1: Where electric
2008 NEC
of the secondary conductor.
240.21 Location in Circuit.
(C) Transformer Secondary
Conductors.
(3) Industrial Installation Secondary
Conductors Not over 7.5 m (25 ft)
Long. For industrial installations only,
where the length of the secondary
conductors does not exceed 7.5 m (25
ft) and complies with all of the
following:
(1) Conditions of maintenance and
supervision ensure that only
qualified persons service the
systems.
240.21 Location in Circuit.
(H) Battery Conductors. Overcurrent
protection shall be permitted to be
installed as close as practicable to the
storage battery terminals in a nonhazardous location. Installation of the
overcurrent protection within a
hazardous location shall also be
permitted.
240.24 Location in or on Premises.
(B) Occupancy. Each occupant shall
have ready access to all overcurrent
devices protecting the conductors
supplying that occupancy, unless
otherwise permitted in 240.24(B)(1)
and (B)(2).
Page 30 of 361
Change Description and Impact to
Worker Safety
New requirement inserted ahead of the
three existing requirements to assure
that only qualified personnel work on
the system.
As Safe or Safer.
New section added to address
hazardous locations and overcurrent
protective device location.
As Safe or Safer.
Converts governing by exception into
positive Code language in keeping with
NEC Style Manual and to clarify the
intent that only overcurrent protective
devices for permanent cooking
appliances require guest access.
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service and electrical maintenance are
provided by the building management
and where these are under continuous
building management supervision, the
service overcurrent devices and feeder
overcurrent devices supplying more
than one occupancy shall be permitted
to be accessible to only authorized
management personnel in the
following:
(1) Multiple-occupancy buildings
(2) Guest rooms or guest suites of
hotels and motels that are intended for
transient occupancy
Exception No. 2: Where electric
service and electrical maintenance are
provided by the building management
and where these are under continuous
building management supervision, the
branch circuit overcurrent devices
supplying any guest rooms or guest
suites shall be permitted to be
accessible to only authorized
management personnel for guest
rooms of hotels and motels that are
intended for transient occupancy.
240.24 Location in or on Premises.
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Change Description and Impact to
Worker Safety
As Safe or Safer.
(1) Service and Feeder Overcurrent
Devices. Where electric service and
electrical maintenance are provided by
the building management and where
these are under continuous building
management supervision, the service
overcurrent devices and feeder
overcurrent devices supplying more
than one occupancy shall be permitted
to be accessible only to authorized
management personnel in the
following:
(1) Multiple-occupancy buildings
(2) Guest rooms or guest suites
(2) Branch-Circuit Overcurrent
Devices. Where electric service and
electrical maintenance are provided by
the building management and where
these are under continuous building
management supervision, the branchcircuit overcurrent devices supplying
any guest rooms or guest suites
without permanent provisions for
cooking shall be permitted to be
accessible only to authorized
management personnel.
240.24 Location in or on Premises.
(F) Not Located over Steps.
Overcurrent devices shall not be
Page 31 of 361
New section to eliminate panels being
installed over steps.
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located over steps of a stairway.
240.86 Series Ratings.
(A) Selected Under Engineering
Supervision in Existing Installations.
The series rated combination devices
shall be selected by a licensed
professional engineer engaged
primarily in the design or maintenance
of electrical installations. The selection
shall be documented and stamped by
the professional engineer. This
documentation shall be available to
those authorized to design, install,
inspect, maintain, and operate the
system. This series combination rating,
including identification of the upstream
device, shall be field marked on the
end use equipment.
VIII. Supervised Industrial Installations
240.92 Location in Circuit. An
overcurrent device shall be connected
in each ungrounded circuit conductor
as required in 240.92(A) through (D).
240.86 Series Ratings.
(A) Selected Under Engineering
Supervision in Existing Installations.
The series rated combination devices
shall be selected by a licensed
professional engineer engaged
primarily in the design or maintenance
of electrical installations. The selection
shall be documented and stamped by
the professional engineer. This
documentation shall be available to
those authorized to design, install,
inspect, maintain, and operate the
system. This series combination rating,
including identification of the upstream
device, shall be field marked on the
end use equipment.
For calculated applications, the
engineer shall ensure that the
downstream circuit breaker(s) that are
part of the series combination remain
passive during the interruption period
of the line side fully rated, currentlimiting device.
VIII. Supervised Industrial Installations
240.92 Location in Circuit. An
overcurrent device shall be connected
in each ungrounded circuit conductor
as required in 240.92(A) through (E).
Page 32 of 361
Change Description and Impact to
Worker Safety
Improves safety by reducing obstacles
to access to electrical panels.
Added section to address the need to
assure that the downstream device
does not operate during the fault
clearing operation.
As Safe or Safer.
New section inserted to address the
need for sizing information for feeder
taps not previously provided.
As Safe or Safer.
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(A) Feeder and Branch-Circuit
Conductors. Feeder and branch-circuit
conductors shall be protected at the
point the conductors receive their
supply as permitted in 240.21 or as
otherwise permitted in 240.92(B), (C),
or (D).
(A) Feeder and Branch-Circuit
Conductors. Feeder and branch-circuit
conductors shall be protected at the
point the conductors receive their
supply as permitted in 240.21 or as
otherwise permitted in 240.92(B), (C),
or (D).
(B) Feeder Taps. For feeder taps
specified in 240.21(B)(2), (B)(3), and
(B)(4), the tap conductors shall be
permitted to be sized in accordance
with Table 240.92(B).
(C) Transformer Secondary
Conductors of Separately Derived
Systems. Conductors shall be
permitted to be connected to a
transformer secondary of a separately
derived system, without overcurrent
protection at the connection, where the
conditions of 240.92(C)(1), (C)(2), and
(C)(3) are met.
Article 250
250.4 General Requirements for
Grounding and Bonding.
(B) Ungrounded Systems.
(4) Path for Fault Current. Electrical
equipment, wiring, and other
electrically conductive material likely to
become energized shall be installed in
a manner that creates a low
(B) Transformer Secondary
Conductors of Separately Derived
Systems. Conductors shall be
permitted to be connected to a
transformer secondary of a separately
derived system, without overcurrent
protection at the connection, where the
conditions of 240.92(B)(1), (B)(2), and
(B)(3) are met.
250.4 General Requirements for
Grounding and Bonding.
(B) Ungrounded Systems.
(4) Path for Fault Current. Electrical
equipment, wiring, and other
electrically conductive material likely to
become energized shall be installed in
a manner that creates a permanent,
Page 33 of 361
Change Description and Impact to
Worker Safety
Modified to eliminate the “permanent”
circuit reference and to clarify that it is
specifically a ground fault from another
phase that is the real concern.
As Safe or Safer.
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impedance circuit from any point on
the wiring system to the electrical
supply source to facilitate the operation
of overcurrent devices should a second
ground fault from a different phase
occur on the wiring system. The earth
shall not be considered as an effective
fault-current path.
250.6 Objectionable Current over
250.6 Objectionable Current.
Grounding Conductors.
(A) Arrangement to Prevent
(A) Arrangement to Prevent
Objectionable Current.
Objectionable Current.
The grounding of electrical systems,
The grounding of electrical systems,
circuit conductors, surge arresters,
circuit conductors, surge arresters, and surge-protective devices, and
conductive non–current-carrying
conductive normally non–currentmaterials and equipment shall be
carrying metal parts of equipment shall
installed and arranged in a manner that be installed and arranged in a manner
will prevent objectionable current over
that will prevent objectionable current.
the grounding conductors or grounding
paths.
250.6 Objectionable Current.
250.6 Objectionable Current.
(B) Alterations to Stop Objectionable
(B) Alterations to Stop Objectionable
Current. If the use of multiple
Current. If the use of multiple
grounding connections results in
grounding connections results in
objectionable current, one or more of
objectionable current, one or more of
the following alterations shall be
the following alterations shall be
permitted to be made, provided that
permitted to be made, provided that
the requirements of 250.4(A)(5) or
the requirements of 250.4(A)(5) or
(B)(4) are met:
(B)(4) are met:
(1) Discontinue one or more but not all (1) Discontinue one or more but not all
of such grounding connections.
of such grounding connections.
Change Description and Impact to
Worker Safety
low-impedance circuit from any point
on the wiring system to the electrical
supply source to facilitate the operation
of overcurrent devices should a second
fault occur on the wiring system. The
earth shall not be considered as an
effective fault-current path.
Page 34 of 361
Modified to simplify wording and to
clarify that it is the metal parts of
equipment not normally carrying
current that must meet the grounding
requirements for objectionable current.
As Safe or Safer.
Clarified to specifically address the
conductive path causing the
objectionable current and not just any
interconnecting grounding conductors.
As Safe or Safer.
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(2) Change the locations of the
grounding connections.
(3) Interrupt the continuity of the
conductor or conductive path
interconnecting the grounding
connections.
(4) Take other suitable remedial and
approved action.
250.6 Objectionable Current.
(D) Limitations to Permissible
Alterations. The provisions of this
section shall not be considered as
permitting electronic equipment from
being operated on ac systems or
branch circuits that are not grounded
as required by this article. Currents
that introduce noise or data errors in
electronic equipment shall not be
considered the objectionable currents
addressed in this section.
250.8 Connection of Grounding and
Bonding Equipment. Grounding
conductors and bonding jumpers shall
be connected by exothermic welding,
listed pressure connectors, listed
clamps, or other listed means.
Connection devices or fittings that
depend solely on solder shall not be
used. Sheet metal screws shall not be
used to connect grounding conductors
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Change Description and Impact to
Worker Safety
(2) Change the locations of the
grounding connections.
(3) Interrupt the continuity of the
conductor or conductive path causing
the objectionable current.
(4) Take other suitable remedial and
approved action.
250.6 Objectionable Current.
(D) Limitations to Permissible
Alterations. The provisions of this
section shall not be considered as
permitting electronic equipment from
being operated on ac systems or
branch circuits that are not connected
to an equipment grounding conductor
as required by this article. Currents
that introduce noise or data errors in
electronic equipment shall not be
considered the objectionable currents
addressed in this section.
250.8 Connection of Grounding and
Bonding Equipment.
(A) Permitted Methods. Grounding
conductors and bonding jumpers shall
be connected by one of the following
means:
(1) Listed pressure connectors
(2) Terminal bars
(3) Pressure connectors listed as
grounding and bonding equipment
Page 35 of 361
Clarifies the distinction of grounded
versus connected to an equipment
grounding conductor.
As Safe or Safer.
Reworked section to delineate the
specific methods acceptable for
connection of grounding conductors
and to allow any listed means to be
used.
As Safe or Safer.
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or connection devices to enclosures.
II. System Grounding
250.20 Alternating-Current Systems to
Be Grounded.
(D) Separately Derived Systems.
Separately derived systems, as
covered in 250.20(A) or (B), shall be
grounded as specified in 250.30.
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Change Description and Impact to
Worker Safety
(4) Exothermic welding process
(5) Machine screw-type fasteners that
engage not less than two threads or
are secured with a nut
(6) Thread-forming machine screws
that engage not less than two threads
in the enclosure
(7) Connections that are part of a listed
assembly
(8) Other listed means
(B) Methods Not Permitted.
Connection devices or fittings that
depend solely on solder shall not be
used.
II. System Grounding
250.20 Alternating-Current Systems to
Be Grounded.
(D) Separately Derived Systems.
Separately derived systems, as
covered in 250.20(A) or (B), shall be
grounded as specified in 250.30(A).
Where an alternate source such as an
on-site generator is provided with
transfer equipment that includes a
grounded conductor that is not solidly
interconnected to the service-supplied
grounded conductor, the alternate
source (derived system) shall be
grounded in accordance with
250.30(A).
Page 36 of 361
Added section to address specific case
of the separately derived system
grounding when alternate source is a
generator through a transfer operation.
As Safe or Safer.
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250.21 Alternating-Current Systems of
50 Volts to 1000 Volts Not Required to
Be Grounded.
250.21 Alternating-Current Systems of
50 Volts to 1000 Volts Not Required to
Be Grounded.
The following ac systems of 50 volts to
1000 volts shall be permitted to be
grounded but shall not be required to
be grounded:
(1) Electric systems used exclusively to
supply industrial electric furnaces for
melting, refining, tempering, and the
like
(2) Separately derived systems used
exclusively for rectifiers that supply
only adjustable-speed industrial drives
(3) Separately derived systems
supplied by transformers that have a
primary voltage rating less than 1000
volts, provided that all the following
conditions are met:
a. The system is used exclusively for
control circuits.
b. The conditions of maintenance and
supervision ensure that only qualified
persons service the installation.
c. Continuity of control power is
required.
d. Ground detectors are installed on
the control system.
(4) Other systems that are not required
to be grounded in accordance with the
(A) General. The following ac systems
of 50 volts to 1000 volts shall be
permitted to be grounded but shall not
be required to be grounded:
(1) Electrical systems used exclusively
to supply industrial electric furnaces for
melting, refining, tempering, and the
like
(2) Separately derived systems used
exclusively for rectifiers that supply
only adjustable-speed industrial drives
(3) Separately derived systems
supplied by transformers that have a
primary voltage rating less than 1000
volts, provided that all the following
conditions are met:
a. The system is used exclusively for
control circuits.
b. The conditions of maintenance and
supervision ensure that only qualified
persons service the installation.
c. Continuity of control power is
required.
(4) Other systems that are not required
to be grounded in accordance with the
requirements of 250.20(B)
Page 37 of 361
Change Description and Impact to
Worker Safety
Modified to clarify the intent of
requiring ground detectors and to
specify which systems must have them
installed.
As Safe or Safer.
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requirements of 250.20(B).
Where an alternating-current system is
not grounded as permitted in 250.21(1)
through (4), ground detectors shall be
installed on the system.
(B) Ground Detectors. Ungrounded
alternating current systems as
permitted in 250.21(A)(1) through
(A)(4) operating at not less than 120
volts and not exceeding 1000 volts
shall have ground detectors installed
on the system.
250.22 Circuits Not to Be Grounded.
The following circuits shall not be
grounded:
(1) Circuits for electric cranes
operating over combustible fibers in
Class III locations, as provided in
503.155
(2) Circuits in health care facilities as
provided in 517.61 and 517.160
(3) Circuits for equipment within
electrolytic cell working zone as
provided in Article 668
(4) Secondary circuits of lighting
systems as provided in 411.5(A)
(5) Secondary circuits of lighting
systems as provided in 680.23(A)(2).
250.24 Grounding Service-Supplied
Alternating-Current Systems.
(A) System Grounding Connections.
(1) General. The grounding electrode
conductor connection shall be made at
any accessible point from the load end
of the service drop or service lateral to
and including the terminal or bus to
250.22 Circuits Not to Be Grounded.
The following circuits shall not be
grounded:
(1) Circuits for electric cranes
operating over combustible fibers in
Class III locations, as provided in
503.155
(2) Circuits in health care facilities as
provided in 517.61 and 517.160
(3) Circuits for equipment within
electrolytic cell working zone as
provided in Article 668
(4) Secondary circuits of lighting
systems as provided in 411.5(A)
250.24 Grounding Service-Supplied
Alternating-Current Systems.
(A) System Grounding Connections.
(1) General. The connection shall be
made at any accessible point from the
load end of the service drop or service
lateral to and including the terminal or
bus to which the grounded service
Page 38 of 361
Change Description and Impact to
Worker Safety
Added exemption for transformers for
lighting systems covered in 680.23
Underwater Luminaires.
As Safe or Safer.
Clarifies that it is specifically the
grounding electrode conductor
connection addressed by this section.
As Safe or Safer.
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conductor is connected at the service
disconnecting means.
250.24 Grounding Service-Supplied
Alternating-Current Systems.
(A) System Grounding Connections.
(5) Load-Side Grounding Connections.
A grounding connection shall not be
made to any grounded conductor on
the load side of the service
disconnecting means except as
otherwise permitted in this article.
250.24 Grounding Service-Supplied
Alternating-Current Systems.
(C) Grounded Conductor Brought to
Service Equipment. Where an ac
system operating at less than 1000
volts is grounded at any point, the
grounded conductor(s) shall be run to
each service disconnecting means and
shall be bonded to each disconnecting
means enclosure. The grounded
conductor(s) shall be installed in
accordance with 250.24(C)(1) through
(C)(3).
Exception: Where more than one
service disconnecting means are
2008 NEC
which the grounded service conductor
is connected at the service
disconnecting means.
250.24 Grounding Service-Supplied
Alternating-Current Systems.
(A) System Grounding Connections.
(5) Load-Side Grounding Connections.
A grounded conductor shall not be
connected to normally non–current
carrying metal parts of equipment, to
equipment grounding conductor(s), or
be reconnected to ground on the load
side of the service disconnecting
means except as otherwise permitted
in this article.
250.24 Grounding Service-Supplied
Alternating-Current Systems.
(C) Grounded Conductor Brought to
Service Equipment. Where an ac
system operating at less than 1000
volts is grounded at any point, the
grounded conductor(s) shall be run to
each service disconnecting means and
shall be connected to each
disconnecting means grounded
conductor(s) terminal or bus. A main
bonding jumper shall connect the
grounded conductor(s) to each service
disconnecting means enclosure. The
grounded conductor(s) shall be
installed in accordance with
Page 39 of 361
Change Description and Impact to
Worker Safety
Clarifies that the grounded conductor
(neutral) is not to be grounded to
anything other than the proper
connection at the service point.
As Safe or Safer.
Clarified the connection requirements
for the grounded conductor at the
service point disconnect enclosure.
As Safe or Safer.
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located in an assembly listed for use
as service equipment, it shall be
permitted to run the grounded
conductor(s) to the assembly, and the
conductor(s) shall be bonded to the
assembly enclosure.
2008 NEC
250.24(C)(1) through (C)(3).
250.28 Main Bonding Jumper and
System Bonding Jumper.
Exception: Where more than one
service disconnecting means are
located in a single assembly listed for
use as service equipment, it shall be
permitted to run the grounded
conductor(s) to the assembly common
grounded conductor(s) terminal or bus.
The assembly shall include a main
bonding jumper for connecting the
grounded conductor(s) to the assembly
enclosure.
250.24 Grounding Service-Supplied
Alternating-Current Systems.
(D) Grounding Electrode Conductor. A
grounding electrode conductor shall be
used to connect the equipment
grounding conductors, the serviceequipment enclosures, and, where the
system is grounded, the grounded
service conductor to the grounding
electrode(s) required by Part III of this
article. This conductor shall be sized in
accordance with 250.66.
250.28 Main Bonding Jumper and
System Bonding Jumper.
(C) Attachment. Main bonding jumpers
and system bonding jumpers shall be
attached in the manner specified by
(C) Attachment. Main bonding jumpers
and system bonding jumpers shall be
connected in the manner specified by
250.24 Grounding Service-Supplied
Alternating-Current Systems.
(D) Grounding Electrode Conductor. A
grounding electrode conductor shall be
used to connect the equipment
grounding conductors, the serviceequipment enclosures, and, where the
system is grounded, the grounded
service conductor to the grounding
electrode(s) required by Part III of this
article.
Change Description and Impact to
Worker Safety
Page 40 of 361
Added sizing requirement for the
grounding electrode conductor.
As Safe or Safer.
Modified to emphasize “connected”
versus just attached to assure good
electrical path. Added new sections (2)
and (3) to specifically address the
needs for bonding in services or
separately derived systems with more
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the applicable provisions of 250.8.
the applicable provisions of 250.8.
(D) Size. Main bonding jumpers and
system bonding jumpers shall not be
smaller than the sizes shown in Table
250.66. Where the supply conductors
are larger than 1100 kcmil copper or
1750 kcmil aluminum, the bonding
jumper shall have an area that is not
less than 121⁄2 percent of the area of
the largest phase conductor except
that, where the phase conductors and
the bonding jumper are of different
materials (copper or aluminum), the
minimum size of the bonding jumper
shall be based on the assumed use of
phase conductors of the same material
as the bonding jumper and with an
ampacity equivalent to that of the
installed phase conductors.
(D) Size. Main bonding jumpers and
system bonding jumpers shall be sized
in accordance with 250.28(D)(1)
through (D)(3).
(1) General. Main bonding jumpers and
system bonding jumpers shall not be
smaller than the sizes shown in
Table 250.66. Where the supply
conductors are larger than 1100 kcmil
copper or 1750 kcmil aluminum, the
bonding jumper shall have an area that
is not less than 121⁄2 percent of the
area of the largest phase conductor
except that, where the phase
conductors and the bonding jumper are
of different materials (copper or
aluminum), the minimum size of the
bonding jumper shall be based on the
assumed use of phase conductors of
the same material as the bonding
jumper and with an ampacity
equivalent to that of the installed phase
conductors.
(2) Main Bonding Jumper for Service
with More Than One Enclosure. Where
a service consists of more than a
single enclosure as permitted in
Page 41 of 361
Change Description and Impact to
Worker Safety
than one enclosure.
As Safe or Safer.
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Change Description and Impact to
Worker Safety
230.71(A), the main bonding jumper for
each enclosure shall be sized in
accordance with 250.28(D)(1) based
on the largest ungrounded service
conductor serving that enclosure.
250.30 Grounding Separately Derived
Alternating-Current Systems.
(A) Grounded Systems. A separately
derived ac system that is grounded
shall comply with 250.30(A)(1) through
(A)(8). A grounding connection shall
not be made to any grounded circuit
conductor on the load side of the point
of grounding of the separately derived
(3) Separately Derived System with
More Than One Enclosure. Where a
separately derived system supplies
more than a single enclosure, the
system bonding jumper
for each enclosure shall be sized in
accordance with 250.28(D)(1) based
on the largest ungrounded feeder
conductor serving that enclosure, or a
single system bonding jumper shall be
installed at the source and sized in
accordance with 250.28(D)(1) based
on the equivalent size of the largest
supply conductor determined by the
largest sum of the areas of the
corresponding conductors of each set.
250.30 Grounding Separately Derived
Alternating-Current Systems.
(A) Grounded Systems. A separately
derived ac system that is grounded
shall comply with 250.30(A)(1) through
(A)(8). Except as otherwise permitted
in this article, a grounded conductor
shall not be connected to normally non
current-carrying metal parts of
Page 42 of 361
Modified to clarify that the grounded
conductor is not to be connected to
any grounded non current-carrying
metal part whether it is a conductor or
not.
As Safe or Safer.
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system except as otherwise permitted
in this article.
250.30 Grounding Separately Derived
Alternating-Current Systems.
(A) Grounded Systems.
(4) Grounding Electrode Conductor,
Multiple Separately Derived Systems.
Where more than one separately
derived system is installed, it shall be
permissible to connect a tap from each
separately derived system to a
common grounding electrode
conductor. Each tap conductor shall
connect the grounded conductor of the
separately derived system to the
common grounding electrode
conductor. The grounding electrode
conductors and taps shall comply with
250.30(A)(4)(a) through (A)(4)(c).
250.30 Grounding Separately Derived
Alternating-Current Systems.
(A) Grounded Systems.
2008 NEC
equipment, to equipment grounding
conductors, or be reconnected to
ground on the load side of the point of
grounding of a separately derived
system.
250.30 Grounding Separately Derived
Alternating-Current Systems.
(A) Grounded Systems.
(4) Grounding Electrode Conductor,
Multiple Separately Derived Systems.
Where more than one separately
derived system is installed, it shall be
permissible to connect a tap from each
separately derived system to a
common grounding electrode
conductor. Each tap conductor shall
connect the grounded conductor of the
separately derived system to the
common grounding electrode
conductor. The grounding electrode
conductors and taps shall comply with
250.30(A)(4)(a) through (A)(4)(c). This
connection shall be made at the same
point on the separately derived system
where the system bonding jumper is
installed.
250.30 Grounding Separately Derived
Alternating-Current Systems.
(A) Grounded Systems.
Page 43 of 361
Change Description and Impact to
Worker Safety
Added specific connection
requirements for the connection of the
separately derived system grounding
electrode conductors.
As Safe or Safer.
Specifies connection to grounded
conductor which effectively bonds the
building steel to the system as
originally intended.
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(6) Bonding. Structural steel and metal
piping shall be bonded in accordance
with 250.104(D).
(6) Bonding. Structural steel and metal
piping shall be connected to the
grounded conductor of a separately
derived system in accordance with
250.104(D).
250.32 Buildings or Structures
Supplied by a Feeder(s) or Branch
Circuit(s).
250.32 Buildings or Structures
Supplied by a Feeder(s) or Branch
Circuit(s).
(B) Grounded Systems. For a
grounded system at the separate
building or structure, the connection to
the grounding electrode and grounding
or bonding of equipment, structures, or
frames required to be grounded or
bonded shall comply with either
250.32(B)(1) or (B)(2).
(B) Grounded Systems. For a
grounded system at the separate
building or structure, an equipment
grounding conductor as described in
250.118 shall be run with the supply
conductors and be connected to the
building or structure disconnecting
means and to the grounding
electrode(s). The equipment grounding
conductor shall be used for grounding
or bonding of equipment, structures, or
frames required to be grounded or
bonded. The equipment grounding
conductor shall be sized in accordance
with 250.122. Any installed grounded
conductor shall not be connected to
the equipment grounding conductor or
to the grounding electrode(s).
(1) Equipment Grounding Conductor.
An equipment grounding conductor as
described in 250.118 shall be run with
the supply conductors and connected
to the building or structure
disconnecting means and to the
grounding electrode(s). The equipment
grounding conductor shall be used for
grounding or bonding of equipment,
structures, or frames required to be
grounded or bonded. The equipment
Exception: For existing premises wiring
grounding conductor shall be sized in
systems only, the grounded conductor
accordance with 250.122. Any installed run with the supply to the building or
Page 44 of 361
Change Description and Impact to
Worker Safety
As Safe or Safer.
Modified to specifically address the
requirement for an equipment
grounding conductor to be installed
and change the section to only allow
the grounded conductor to be
connected for situations meeting the
exception criteria.
As Safe or Safer.
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grounded conductor shall not be
connected to the equipment grounding
conductor or to the grounding
electrode(s).
(2) Grounded Conductor. Where (1) an
equipment grounding conductor is not
run with the supply to the building or
structure, (2) there are no continuous
metallic paths bonded to the grounding
system in each building or structure
involved, and (3) ground-fault
protection of equipment has not been
installed on the supply side of the
feeder(s), the grounded conductor run
with the supply to the building or
structure shall be connected to the
building or structure disconnecting
means and to the grounding
electrode(s) and shall be used for
grounding or bonding of equipment,
structures, or frames required to be
grounded or bonded. The size of the
grounded conductor shall not be
smaller than the larger of either of the
following:
(1) That required by 220.61
(2) That required by 250.122
250.32 Buildings or Structures
Supplied by a Feeder(s) or Branch
Circuit(s).
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Change Description and Impact to
Worker Safety
structure shall be permitted to be
connected to the building or structure
disconnecting means and to the
grounding electrode(s) and shall be
used for grounding or bonding of
equipment, structures, or frames
required to be grounded or bonded
where all the requirements of (1), (2),
and (3) are met:
(1) An equipment grounding conductor
is not run with the supply to the
building or structure.
(2) There are no continuous metallic
paths bonded to the grounding system
in each building or structure involved.
(3) Ground-fault protection of
equipment has not been installed on
the supply side of the feeder(s).
Where the grounded conductor is used
for grounding in accordance with the
provision of this exception, the size of
the grounded conductor shall not be
smaller than the larger of either of the
following:
(1) That required by 220.61
(2) That required by 250.122
250.32 Buildings or Structures
Supplied by a Feeder(s) or Branch
Circuit(s).
Page 45 of 361
Modified to assure that the grounded
conductor is not connected to any
grounded metal part other than at the
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(D) Disconnecting Means Located in
Separate Building or Structure on the
Same Premises. Where one or more
disconnecting means supply one or
more additional buildings or structures
under single management, and where
these disconnecting means are located
remote from those buildings or
structures in accordance with the
provisions of 225.32, Exception Nos. 1
and 2, all of the following conditions
shall be met:
Change Description and Impact to
Worker Safety
grounding electrode connection and
that the term connection is used to
reinforce the idea of good electrical
continuity.
(D) Disconnecting Means Located in
Separate Building or Structure on the
Same Premises. Where one or more
disconnecting means supply one or
more additional buildings or structures As Safe or Safer.
under single management, and where
these disconnecting means are located
remote from those buildings or
structures in accordance with the
provisions of 225.32, Exception No. 1
and No. 2, 700.12(B)(6), 701.11(B)(5),
or 702.11, all of the following
conditions shall be met:
(1) The connection of the grounded
(1) The connection of the grounded
conductor to the grounding electrode at conductor to the grounding electrode,
a separate building or structure shall
to normally non-current-carrying metal
not be made.
parts of equipment, or to the
equipment grounding conductor at a
separate building or structure shall not
be made.
(2) An equipment grounding conductor
for grounding any non-current-carrying
equipment, interior metal piping
systems, and building or structural
metal frames is run with the circuit
conductors to a separate building or
structure and bonded to existing
grounding electrode(s) required in Part
III of this article, or, where there are no
(2) An equipment grounding conductor
for grounding and bonding any
normally non-current-carrying metal
parts of equipment, interior metal
piping systems, and building or
structural metal frames is run with the
circuit conductors to a separate
building or structure and connected to
existing grounding electrode(s)
Page 46 of 361
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existing electrodes, the grounding
electrode(s) required in Part III of this
article shall be installed where a
separate building or structure is
supplied by more than one branch
circuit.
required in Part III of this article, or,
where there are no existing electrodes,
the grounding electrode(s) required in
Part III of this article shall be installed
where a separate building or structure
is supplied by more than one branch
circuit.
(3) Bonding the equipment grounding
conductor to the grounding electrode at
a separate building or structure shall
be made in a junction box, panelboard,
or similar enclosure located
immediately inside or outside the
separate building or structure.
(3) The connection between the
equipment grounding conductor and
the grounding electrode at a separate
building or structure shall be made in a
junction box, panelboard, or similar
enclosure located immediately inside
or outside the separate building or
structure.
250.34 Portable and Vehicle-Mounted
Generators.
(A) Portable Generators. The frame of
a portable generator shall not be
required to be connected to a
grounding electrode as defined in
250.52 for a system supplied by the
generator under the following
conditions:
(1) The generator supplies only
equipment mounted on the generator,
cord-and-plug-connected equipment
through receptacles mounted on the
generator, or both, and
(2) The normally non–current-carrying
250.34 Portable and Vehicle-Mounted
Generators.
(A) Portable Generators. The frame of
a portable generator shall not be
required to be connected to a
grounding electrode as defined in
250.52 for a system supplied by the
generator under the following
conditions:
(1) The generator supplies only
equipment mounted on the generator,
cord-and-plug-connected equipment
through receptacles mounted on the
generator, or both, and
(2) The non–current-carrying metal
Page 47 of 361
Change Description and Impact to
Worker Safety
Modified to address and emphasize
“normally” non-current carrying metal
parts as throughout the Code and to
reiterate “connected” instead of
“bonded”.
As Safe or Safer.
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parts of equipment and the equipment
grounding conductor terminals of the
receptacles are bonded to the
generator frame.
250.34 Portable and Vehicle-Mounted
Generators.
(B) Vehicle-Mounted Generators. The
frame of a vehicle shall not be required
to be connected to a grounding
electrode as defined in 250.52 for a
system supplied by a generator
located on this vehicle under the
following conditions:
(1) The frame of the generator is
bonded to the vehicle frame, and
(2) The generator supplies only
equipment located on the vehicle or
cord-and-plug-connected equipment
through receptacles mounted on the
vehicle, or both equipment located on
the vehicle and cord-and-plugconnected equipment through
receptacles mounted on the vehicle
or on the generator, and
(3) The non–current-carrying metal
parts of equipment and the equipment
grounding conductor terminals of the
receptacles are bonded to the
generator frame.
250.34 Portable and Vehicle-Mounted
Generators.
metal parts of equipment and the
equipment grounding conductor
terminals of the receptacles are
connected to the generator frame.
250.34 Portable and Vehicle-Mounted
Generators.
(B) Vehicle-Mounted Generators. The
frame of a vehicle shall not be required
to be connected to a grounding
electrode as defined in 250.52 for a
system supplied by a generator located
on this vehicle under the following
conditions:
(1) The frame of the generator is
bonded to the vehicle frame, and
(2) The generator supplies only
equipment located on the vehicle or
cord-and-plug-connected equipment
through receptacles mounted on the
vehicle, or both equipment located on
the vehicle and cord-and-plugconnected equipment through
receptacles mounted on the vehicle
or on the generator, and
(3) The normally non–current-carrying
metal parts of equipment and the
equipment grounding conductor
terminals of the receptacles are
connected to the generator frame.
250.34 Portable and Vehicle-Mounted
Generators.
Page 48 of 361
Change Description and Impact to
Worker Safety
Modified to address and emphasize
“normally” non-current carrying metal
parts as throughout the Code and to
reiterate “connected” instead of
“bonded”.
As Safe or Safer.
Modified to reiterate “connected”
instead of “bonded”.
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(C) Grounded Conductor Bonding. A
system conductor that is required to be
grounded by 250.26 shall be bonded
to the generator frame where the
generator is a component of a
separately derived system.
(C) Grounded Conductor Bonding. A
system conductor that is required to be
grounded by 250.26 shall be
connected to the generator frame
where the generator is a component of
a separately derived system.
250.35 Permanently Installed
Generators. A conductor that provides
an effective ground-fault current path
shall be installed with the supply
conductors from a permanently
installed generator(s) to the first
disconnecting mean(s) in accordance
with (A) or (B).
(A) Separately Derived System. Where
the generator is installed as a
separately derived system, the
requirements in 250.30 shall apply.
(B) Non-separately Derived System.
Where the generator is not installed as
a separately derived system, an
equipment bonding jumper shall be
installed between the generator
equipment grounding terminal and the
equipment grounding terminal or bus of
the enclosure of supplied
disconnecting mean(s) in accordance
with (B)(1) or (B)(2).
Page 49 of 361
Change Description and Impact to
Worker Safety
As Safe or Safer.
New section created to answer
concerns about the specific grounding
and bonding requirements for
permanently installed generators
previously not addressed.
As Safe or Safer.
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Change Description and Impact to
Worker Safety
(1) Supply Side of Generator
Overcurrent Device. The equipment
bonding jumper on the supply side of
each generator overcurrent device
shall be sized in accordance with
250.102(C) based on the size of the
conductors supplied by the generator.
250.36 High-Impedance Grounded
Neutral Systems.
High-impedance grounded neutral
systems in which a grounding
impedance, usually a resistor, limits
the ground fault current to a low value
shall be permitted for 3-phase ac
systems of 480 volts to 1000 volts
where all the following conditions are
met:
(1) The conditions of maintenance and
supervision ensure that only qualified
persons service the installation.
(2) Continuity of power is required.
(3) Ground detectors are installed on
the system.
(2) Load Side of Generator
Overcurrent Device. The equipment
grounding conductor on the load side
of each generator overcurrent device
shall be sized in accordance with
250.102(D) based on the rating of the
overcurrent device supplied.
250.36 High-Impedance Grounded
Neutral Systems.
High-impedance grounded neutral
systems in which a grounding
impedance, usually a resistor, limits
the ground fault current to a low value
shall be permitted for 3-phase ac
systems of 480 volts to 1000 volts
where all the following conditions are
met:
(1) The conditions of maintenance and
supervision ensure that only qualified
persons service the installation.

(2) Ground detectors are installed on
the system.
Page 50 of 361
Removed the stipulation that
“continuity of power is required” as a
criteria for use of a high impedance
grounding system since the answer to
this question would most certainly be
yes, continuity is required.
As Safe or Safer.
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(4) Line-to-neutral loads are not
served.
250.36 High-Impedance Grounded
Neutral Systems.
(3) Line-to-neutral loads are not
served.
250.36 High-Impedance Grounded
Neutral Systems.
(A) Grounding Impedance Location.
The grounding impedance shall be
installed between the grounding
electrode conductor and the system
neutral. Where a neutral is not
available, the grounding impedance
shall be installed between the
grounding electrode conductor and the
neutral derived from a grounding
transformer.
250.36 High-Impedance Grounded
Neutral Systems.
(A) Grounding Impedance Location.
The grounding impedance shall be
installed between the grounding
electrode conductor and the system
neutral point. Where a neutral point is
not available, the grounding
impedance shall be installed between
the grounding electrode conductor and
the neutral point derived from a
grounding transformer.
250.36 High-Impedance Grounded
Neutral Systems.
(B) Neutral Conductor. The neutral
conductor from the neutral point of the
transformer or generator to its
connection point to the grounding
impedance shall be fully insulated.
The neutral conductor shall have an
ampacity of not less than the maximum
current rating of the grounding
impedance. In no case shall the neutral
conductor be smaller than 8 AWG
copper or 6 AWG aluminum or copperclad aluminum.
(B) Grounded System Conductor. The
grounded system conductor from the
neutral point of the transformer or
generator to its connection point to the
grounding impedance shall be fully
insulated.
The grounded system conductor shall
have an ampacity of not less than the
maximum current rating of the
grounding impedance. In no case shall
the grounded system conductor be
smaller than 8 AWG copper or 6 AWG
aluminum or copper-clad aluminum.
Page 51 of 361
Change Description and Impact to
Worker Safety
Added “point” to emphasize the
specific point to which the grounding
impedance is connected. The definition
of neutral point narrows to options to
assure proper location.
As Safe or Safer.
Replaced “neutral” with “grounded
system” to properly identify the role of
the conductor.
As Safe or Safer.
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250.36 High-Impedance Grounded
Neutral Systems.
250.36 High-Impedance Grounded
Neutral Systems.
(C) System Neutral Connection. The
system neutral conductor shall not be
connected to ground except through
the grounding impedance.
250.36 High-Impedance Grounded
Neutral Systems.
(C) System Grounding Connection.
The system shall not be connected to
ground except through the grounding
impedance.
250.36 High-Impedance Grounded
Neutral Systems.
(D) Neutral Conductor Routing. The
conductor connecting the neutral point
of the transformer or generator to the
grounding impedance shall be
permitted to be installed in a separate
raceway. It shall not be required to run
this conductor with the phase
conductors to the first system
disconnecting means or overcurrent
device.
250.52 Grounding Electrodes.
(A) Electrodes Permitted for
Grounding.
(D) Neutral Point to Grounding
Impedance Conductor Routing. The
conductor connecting the neutral point
of the transformer or generator to the
grounding impedance shall be
permitted to be installed in a separate
raceway from the ungrounded
conductors. It shall not be required to
run this conductor with the phase
conductors to the first system
disconnecting means or overcurrent
device.
250.52 Grounding Electrodes.
(A) Electrodes Permitted for
Grounding.
(2) Metal Frame of the Building or
Structure. The metal frame of the
building or structure, where any of the
following methods are used to make an
earth connection:
(2) Metal Frame of the Building or
Structure. The metal frame of the
building or structure that is connected
to the earth by any of the following
methods:
Page 52 of 361
Change Description and Impact to
Worker Safety
Replaced “neutral” with “grounding” to
properly identify the role of the
conductor.
As Safe or Safer.
Modified wording to properly identify
the role of the conductor.
As Safe or Safer.
Modified to address the specific
actions taken to make the connection
to earth and to reinforce the
connection requirements.
As Safe or Safer.
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(1) 3.0 m (10 ft) or more of a single
structural metal member in direct
contact with the earth or encased in
concrete that is in direct contact with
the earth
(2) The structural metal frame is
bonded to one or more of the
grounding electrodes as defined in
250.52(A)(1), (A)(3), or (A)(4)
(3) The structural metal frame is
bonded to one or more of the
grounding electrodes as defined in
250.52(A)(5) or (A)(6) that comply
with 250.56, or
(4) Other approved means of
establishing a connection to earth.
250.52 Grounding Electrodes.
(A) Electrodes Permitted for
Grounding.
(3) Concrete-Encased Electrode. An
electrode encased by at least 50 mm
(2 in.) of concrete, located within and
near the bottom of a concrete
foundation or footing that is in direct
contact with the earth, consisting of at
least 6.0 m (20 ft) of one or more bare
or zinc galvanized or other electrically
conductive coated steel reinforcing
bars or rods of not less than 13 mm
2008 NEC
(1) 3.0 m (10 ft) or more of a single
structural metal member in direct
contact with the earth or encased in
concrete that is in direct contact with
the earth
(2) Connecting the structural metal
frame to the reinforcing bars of a
concrete-encased electrode as
provided in 250.52(A)(3) or ground
ring as provided in 250.52(A)(4)
(3) Bonding the structural metal
frame to one or more of the
grounding electrodes as defined in
250.52(A)(5) or (A)(7) that comply
with 250.56
(4) Other approved means of
establishing a connection to earth
250.52 Grounding Electrodes.
(A) Electrodes Permitted for
Grounding.
Change Description and Impact to
Worker Safety
Modified to clarify intent and to allow
more than just the bottom of the
concrete encased electrode to qualify
as the section in direct contact with the
(3) Concrete-Encased Electrode. An
earth. In addition, there is no need to
electrode encased by at least 50 mm
connect all of the concrete-encased
(2 in.) of concrete, located horizontally electrodes to the grounding electrode
near the bottom or vertically, and within system as was inferred previously.
that portion of a concrete foundation or
footing that is in direct contact with the As Safe or Safer.
earth, consisting of at least 6.0 m (20
ft) of one or more bare or zinc
galvanized or other electrically
conductive coated steel reinforcing
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(1⁄2 in.) in diameter, or consisting of at
least 6.0 m (20 ft) of bare copper
conductor not smaller than 4 AWG.
Reinforcing bars shall be permitted to
be bonded together by the usual steel
tie wires or other effective means.
bars or rods of not less than 13 mm
(1⁄2 in.) in diameter, or consisting of at
least 6.0 m (20 ft) of bare copper
conductor not smaller than 4 AWG.
Reinforcing bars shall be permitted to
be bonded together by the usual steel
tie wires or other effective means.
Where multiple concrete-encased
electrodes are present at a building or
structure, it shall be permissible to
bond only one into the grounding
electrode system.
250.52 Grounding Electrodes.
(A) Electrodes Permitted for
Grounding.
250.52 Grounding Electrodes.
(A) Electrodes Permitted for
Grounding.
(5) Rod and Pipe Electrodes. Rod and
pipe electrodes shall not be less than
2.5 m (8 ft) in length and shall consist
of the following materials.
(a) Electrodes of pipe or conduit shall
not be smaller than metric designator
21 (trade size 3⁄4) and, where of iron or
steel, shall have the outer surface
galvanized or otherwise metal-coated
for corrosion protection.
(b) Electrodes of rods of iron or steel
shall be at least 15.87 mm (5⁄8 in.) in
diameter. Stainless steel rods less than
16 mm (5⁄8 in.) in diameter, nonferrous
rods, or their equivalent shall be listed
(5) Rod and Pipe Electrodes. Rod and
pipe electrodes shall not be less than
2.44 m (8 ft) in length and shall consist
of the following materials.
(a) Grounding electrodes of pipe or
conduit shall not be smaller than metric
designator 21 (trade size 3⁄4) and,
where of steel, shall have the outer
surface galvanized or otherwise metalcoated for corrosion protection.
(b) Grounding electrodes of stainless
steel and copper or zinc coated steel
shall be at least 15.87 mm (5⁄8 in.) in
diameter, unless listed and not less
than 12.70 mm (1⁄2 in.) in diameter.
Page 54 of 361
Change Description and Impact to
Worker Safety
Modified dimensions to more precisely
indicate the metric equivalents.
Specifically addresses the term
grounding electrode in (b) to rule out
other interpretations and cleared up
the listed equivalent issue surrounding
the minimum size allowed.
No direct impact, but long term
provides longer lasting grounding
electrodes for personnel and
equipment protection.
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and shall not be less than 13 mm (1⁄2
in.) in diameter.
250.52 Grounding Electrodes.
(A) Electrodes Permitted for
Grounding.
250.52 Grounding Electrodes.
(A) Electrodes Permitted for
Grounding.
250.52 Grounding Electrodes.
(6) Other Listed Electrodes. Other
listed grounding electrodes shall be
permitted.
250.52 Grounding Electrodes.
(B) Electrodes Not Permitted for
Grounding. The following shall not be
used as grounding electrodes:
(1) Metal underground gas piping
system
(2) Aluminum electrodes
(B) Not Permitted for Use as
Grounding Electrodes. The following
systems and materials shall not be
used as grounding electrodes:
(1) Metal underground gas piping
systems
(2) Aluminum
250.54 Supplementary Grounding
250.54 Auxiliary Grounding Electrodes.
Electrodes. Supplementary grounding
One or more grounding electrodes
electrodes shall be permitted to be
shall be permitted to be connected to
connected to the equipment grounding the equipment grounding conductors
conductors specified in 250.118 and
specified in 250.118 and shall not be
shall not be required to comply with the required to comply with the electrode
electrode bonding requirements of
bonding requirements of 250.50 or
250.50 or 250.53(C) or the resistance
250.53(C) or the resistance
requirements of 250.56, but the earth
requirements of 250.56, but the earth
shall not be used as an effective
shall not be used as an effective
ground-fault current path as specified
ground-fault current path as specified
in 250.4(A)(5) and 250.4(B)(4).
in 250.4(A)(5) and 250.4(B)(4).
250.64 Grounding Electrode Conductor 250.64 Grounding Electrode Conductor
Page 55 of 361
Change Description and Impact to
Worker Safety
Inserted new (6) to allow any other
listed grounding electrodes to be used
to allow improvements in
manufacturing techniques and new
listings.
As Safe or Safer.
Modified to reinforce the intent that
grounding electrodes is the subject
matter and that the materials or
systems identified are not to be used,
regardless if they are called electrodes
or not.
As Safe or Safer.
Clarified intent since no definition of
supplementary electrodes is presented
and that any additional grounding
electrodes beyond those required top
be connected do not have to meet the
same requirements. This change
allows for easier installations and
additions.
As Safe or Safer.
Inserted specific locations where
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Installation. Grounding electrode
conductors shall be installed as
specified in 250.64(A) through (F).
Change Description and Impact to
Worker Safety
grounding electrode conductors must
comply with the requirements of the
section.
Installation. Grounding electrode
conductors at the service, at each
building or structure where supplied by
a feeder(s) or branch circuit(s), or at a
separately derived system shall be
As Safe or Safer.
installed as specified in 250.64(A)
through (F).
250.64 Grounding Electrode Conductor 250.64 Grounding Electrode Conductor Total rewrite to address the specific
Installation.
Installation.
requirements and to more accurately
identify the equipment and materials
(D) Grounding Electrode Conductor
(D) Service with Multiple Disconnecting involved. The wording regarding taps
Taps. Where a service consists of
Means Enclosures. Where a service
was reinforced with specific reference
more than a single enclosure as
consists of more than a single
to grounding electrodes throughout to
permitted in 230.71(A), it shall be
enclosure as permitted in 230.71(A),
eliminate confusion with other
permitted to connect taps to the
grounding electrode connections shall
ungrounded conductor taps in Section
common grounding electrode
be made in accordance with (D)(1),
240.21.
conductor. Each such tap conductor
(D)(2), or (D)(3).
shall extend to the inside of each such
As Safe or Safer.
enclosure. The common grounding
(1) Grounding Electrode Conductor
electrode conductor shall be sized in
Taps. Where the service is installed as
accordance with 250.66, based on the permitted by 230.40, Exception No. 2,
sum of the circular mil area of the
a common grounding electrode
largest ungrounded service entrance
conductor and grounding electrode
conductors. Where more than one set
conductor taps shall be installed. The
of service entrance conductors as
common grounding electrode
permitted by 230.40, Exception No. 2
conductor shall be sized in accordance
connect directly to a service drop or
with 250.66, based on the sum of the
lateral, the common grounding
circular mil area of the largest
electrode conductor shall be sized in
ungrounded service-entrance
accordance with Table 250.66 Note 1. conductor(s). Where the serviceThe tap conductors shall be permitted
entrance conductors connect directly to
Page 56 of 361
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to be sized in accordance with the
grounding electrode conductors
specified in 250.66 for the largest
conductor serving the respective
enclosures. The tap conductors shall
be connected to the common
grounding electrode conductor in such
a manner that the common grounding
electrode conductor remains without a
splice or joint.
a service drop or service lateral, the
common grounding electrode
conductor shall be sized in accordance
with Table 250.66, Note 1. A tap
conductor shall extend to the inside of
each service disconnecting means
enclosure. The grounding electrode
conductor taps shall be sized in
accordance with 250.66 for the largest
conductor serving the individual
enclosure. The tap conductors shall be
connected to the common grounding
electrode conductor by exothermic
welding or with connectors listed as
grounding and bonding equipment in
such a manner that the common
grounding electrode conductor remains
without a splice or joint.
(2) Individual Grounding Electrode
Conductors. A grounding electrode
conductor shall be connected between
the grounded conductor in each
service equipment disconnecting
means enclosure and the grounding
electrode system. Each grounding
electrode conductor shall be sized in
accordance with 250.66 based on the
service-entrance conductor(s)
supplying the individual service
disconnecting means.
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Change Description and Impact to
Worker Safety
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Change Description and Impact to
Worker Safety
(3) Common Location. A grounding
electrode conductor shall be connected
to the grounded service conductor(s) in
a wireway or other accessible
enclosure on the supply side of the
service disconnecting means. The
connection shall be made with
exothermic welding or a connector
listed as grounding and bonding
equipment. The grounding electrode
conductor shall be sized in accordance
with 250.66 based on the serviceentrance conductor(s) at the common
location where the connection is made.
250.64 Grounding Electrode Conductor 250.64 Grounding Electrode Conductor Elimination of service broadens the
Installation.
Installation.
locations that require bonding per this
section to include those supplied via
(E) Enclosures for Grounding
(E) Enclosures for Grounding
other means such as separately
Electrode Conductors. Ferrous metal
Electrode Conductors. Ferrous metal
derived systems, feeders and branch
enclosures for grounding electrode
enclosures for grounding electrode
circuits.
conductors shall be electrically
conductors shall be electrically
continuous from the point of
continuous from the point of
As Safe or Safer.
attachment to cabinets or equipment to attachment to cabinets or equipment to
the grounding electrode and shall be
the grounding electrode and shall be
securely fastened to the ground clamp securely fastened to the ground clamp
or fitting. Nonferrous metal enclosures or fitting. Nonferrous metal enclosures
shall not be required to be electrically
shall not be required to be electrically
continuous. Ferrous metal enclosures
continuous. Ferrous metal enclosures
that are not physically continuous from that are not physically continuous from
cabinets or equipment to the grounding cabinets or equipment to the grounding
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electrode shall be made electrically
continuous by bonding each end of the
raceway or enclosure to the grounding
electrode conductor. Bonding shall
apply at each end and to all intervening
ferrous raceways, boxes, and
enclosures between the service
equipment and the grounding
electrode. The bonding jumper for a
grounding electrode conductor
raceway or cable armor shall be the
same size as, or larger than, the
required enclosed grounding electrode
conductor. Where a raceway is used
as protection for a grounding electrode
conductor, the installation shall comply
with the requirements of the
appropriate raceway article.
250.64 Grounding Electrode Conductor
Installation.
(F) To Electrode(s). A grounding
electrode conductor shall be permitted
to be run to any convenient grounding
electrode available in the grounding
electrode system, or to one or more
grounding electrode(s) individually, or
to the aluminum or copper busbar as
permitted in 250.64(C). The grounding
electrode conductor shall be sized for
the largest grounding electrode
2008 NEC
Change Description and Impact to
Worker Safety
electrode shall be made electrically
continuous by bonding each end of the
raceway or enclosure to the grounding
electrode conductor. Bonding shall
apply at each end and to all intervening
ferrous raceways, boxes, and
enclosures between the cabinets or
equipment and the grounding
electrode. The bonding jumper for a
grounding electrode conductor
raceway or cable armor shall be the
same size as, or larger than, the
enclosed grounding electrode
conductor. Where a raceway is used
as protection for a grounding electrode
conductor, the installation shall comply
with the requirements of the
appropriate raceway article.
250.64 Grounding Electrode Conductor Modified to place specific requirements
Installation.
on the installation of grounding
electrode conductors and to allow for
(F) Installation to Electrode(s).
use of a listed means for connection to
Grounding electrode conductor(s) and enclosures.
bonding jumpers interconnecting
grounding electrodes shall be installed As Safe or Safer.
in accordance with (1), (2), or (3). The
grounding electrode conductor shall be
sized for the largest grounding
electrode conductor required among all
the electrodes connected to it.
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conductor required among all the
electrodes connected to it.
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Change Description and Impact to
Worker Safety
(1) The grounding electrode conductor
shall be permitted to be run to any
convenient grounding electrode
available in the grounding electrode
system where the other electrode(s), if
any, are connected by bonding
jumpers per 250.53(C).
(2) Grounding electrode conductor(s)
shall be permitted to be run to one or
more grounding electrode(s)
individually.
250.66 Size of Alternating-Current
Grounding Electrode Conductor. The
size of the grounding electrode
conductor of a grounded or
(3) Bonding jumper(s) from grounding
electrode(s) shall be permitted to be
connected to an aluminum or copper
busbar not less than 6 mm × 50 mm
(1⁄4 in. × 2 in.). The busbar shall be
securely fastened and shall be
installed in an accessible location.
Connections shall be made by a listed
connector or by the exothermic welding
process. The grounding electrode
conductor shall be permitted to be run
to the busbar. Where aluminum
busbars are used, the installation shall
comply with 250.64(A).
250.66 Size of Alternating-Current
Grounding Electrode Conductor. The
size of the grounding electrode
conductor at the service, at each
Page 60 of 361
Modified to eliminate the confusion and
misinterpretation of where grounding
electrode conductors need to be
installed in accordance with the
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ungrounded ac system shall not be
building or structure where supplied by
less than given in Table 250.66, except a feeder(s) or branch circuit(s), or at a
as permitted in 250.66(A) through (C). separately derived system of a
grounded or ungrounded ac system
shall not be less than given in Table
250.66, except as permitted in
250.66(A) through (C).
250.68 Grounding Electrode Conductor 250.68 Grounding Electrode Conductor
and Bonding Jumper Connection to
and Bonding Jumper Connection to
Grounding Electrodes.
Grounding Electrodes. The connection
of a grounding electrode conductor at
the service, at each building or
structure where supplied by a feeder(s)
or branch circuit(s), or at a separately
derived system and associated
bonding jumper(s) shall be made as
specified 250.68(A) and (B).
Change Description and Impact to
Worker Safety
requirements of this section.
As Safe or Safer.
Modified to eliminate the confusion and
misinterpretation of where grounding
electrode conductors need to be
installed in accordance with the
requirements of this section.
Exception No. 2 modified to better
explain the requirements.
As Safe or Safer.
(A) Accessibility. The connection of a
grounding electrode conductor or
bonding jumper to a grounding
electrode shall be accessible.
(A) Accessibility. All mechanical
elements used to terminate a
grounding electrode conductor or
bonding jumper to a grounding
electrode shall be accessible.
Exception No. 1: An encased or buried
connection to a concrete-encased,
driven, or buried grounding electrode
shall not be required to be accessible.
Exception No. 1: An encased or buried
connection to a concrete-encased,
driven, or buried grounding electrode
shall not be required to be accessible.
Exception No. 2: An exothermic or
irreversible compression connection to
Exception No. 2: Exothermic or
irreversible compression connections
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fire-proofed structural metal shall not
be required to be accessible.
Change Description and Impact to
Worker Safety
used at terminations, together with the
mechanical means used to attach such
terminations to fireproofed structural
metal whether or not the mechanical
means is reversible, shall not be
required to be accessible.
250.68 Grounding Electrode Conductor 250.68 Grounding Electrode Conductor Removed “permanent” and reworded
and Bonding Jumper Connection to
and Bonding Jumper Connection to
slightly to specifically address that
Grounding Electrodes.
Grounding Electrodes.
there are bonding jumpers not
conductors and that the grounding
(B) Effective Grounding Path. The
(B) Effective Grounding Path. The
path is the important component to
connection of a grounding electrode
connection of a grounding electrode
maintain.
conductor or bonding jumper to a
conductor or bonding jumper to a
grounding electrode shall be made in a grounding electrode shall be made in a Actually improves worker safety by
manner that will ensure a permanent
manner that will ensure an effective
assuring a continuous ground path.
and effective grounding path. Where
grounding path. Where necessary to
necessary to ensure the grounding
ensure the grounding path for a metal
path for a metal piping system used as piping system used as a grounding
a grounding electrode, effective
electrode, bonding shall be provided
bonding shall be provided around
around insulated joints and around any
insulated joints and around any
equipment likely to be disconnected for
equipment likely to be disconnected for repairs or replacement. Bonding
repairs or replacement. Bonding
jumpers shall be of sufficient length to
conductors shall be of sufficient length permit removal of such equipment
to permit removal of such equipment
while retaining the integrity of the
while retaining the integrity of the bond. grounding path.
IV. Enclosure, Raceway, and Service
IV. Enclosure, Raceway, and Service
Modified to differentiate “connected to
Cable Grounding
Cable Connections
the grounded system conductor” from
simply “grounding” which had been
250.80 Service Raceways and
250.80 Service Raceways and
misinterpreted and inconsistently
Enclosures. Metal enclosures and
Enclosures. Metal enclosures and
applied.
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raceways for service conductors and
equipment shall be grounded.
raceways for service conductors and
equipment shall be connected to the
grounded system conductor if the
electrical system is grounded or to the
grounding electrode conductor for
electrical systems that are not
grounded.
Exception: A metal elbow that is
installed in an underground installation
of rigid nonmetallic conduit and is
isolated from possible contact by a
minimum cover of 450 mm (18 in.) to
any part of the elbow shall not be
required to be grounded.
Exception: A metal elbow that is
installed in an underground installation
of rigid nonmetallic conduit and is
isolated from possible contact by a
minimum cover of 450 mm (18 in.) to
any part of the elbow shall not be
required to be connected to the
grounded system conductor or
grounding electrode conductor.
250.84 Underground Service Cable or
Raceway.
250.84 Underground Service Cable or
Raceway.
(A) Underground Service Cable. The
sheath or armor of a continuous
underground metal-sheathed or
armored service cable system that is
bonded to the grounded underground
system shall not be required to be
grounded at the building or structure.
The sheath or armor shall be permitted
to be insulated from the interior metal
raceway conduit or piping.
(A) Underground Service Cable. The
sheath or armor of a continuous
underground metal-sheathed or
armored service cable system that is
connected to the grounded system
conductor on the supply side shall not
be required to be connected to the
grounded system conductor at the
building or structure. The sheath or
armor shall be permitted to be
insulated from the interior metal
Page 63 of 361
Change Description and Impact to
Worker Safety
Actually improves worker safety by
assuring a continuous ground path.
Modified to differentiate “connected to
the grounded system conductor” from
simply “grounding” which had been
misinterpreted and inconsistently
applied.
Actually improves worker safety by
assuring a continuous ground path.
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Change Description and Impact to
Worker Safety
raceway or piping.
(B) Underground Service Raceway
Containing Cable. An underground
metal service raceway that contains a
metal-sheathed or armored cable
bonded to the grounded underground
system shall not be required to be
grounded at the building or structure.
The sheath or armor shall be permitted
to be insulated from the interior metal
raceway or piping.
250.86 Other Conductor Enclosures
and Raceways. Except as permitted by
250.112(I), metal enclosures and
raceways for other than service
conductors shall be grounded.
Exception No. 1: Metal enclosures and
raceways for conductors added to
existing installations of open wire, knob
and tube wiring, and nonmetallicsheathed cable shall not be required to
be grounded where these enclosures
or wiring methods comply with (1)
through (4) as follows:
(1) Do not provide an equipment
(B) Underground Service Raceway
Containing Cable. An underground
metal service raceway that contains a
metal-sheathed or armored cable
connected to the grounded system
conductor shall not be required to be
connected to the grounded system
conductor at the building or structure.
The sheath or armor shall be permitted
to be insulated from the interior metal
raceway or piping.
250.86 Other Conductor Enclosures
and Raceways. Except as permitted by
250.112(I), metal enclosures and
raceways for other than service
conductors shall be connected to the
equipment grounding conductor.
Exception No. 1: Metal enclosures and
raceways for conductors added to
existing installations of open wire, knob
and tube wiring, and nonmetallicsheathed cable shall not be required to
be connected to the equipment
grounding conductor where these
enclosures or wiring methods comply
with (1) through (4) as follows:
(1) Do not provide an equipment
Page 64 of 361
Inserted “connected to the equipment
grounding conductor” in lieu of
“grounded” which had been
misinterpreted and inconsistently
applied.
Actually improves worker safety by
assuring a continuous ground path.
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ground
(2) Are in runs of less than 7.5 m (25
ft)
(3) Are free from probable contact
with ground, grounded metal, metal
lath, or other conductive material
(4) Are guarded against contact by
persons
Exception No. 2: Short sections of
metal enclosures or raceways used to
provide support or protection of cable
assemblies from physical damage shall
not be required to be grounded.
Exception No. 3: A metal elbow shall
not be required to be grounded where
it is installed in a nonmetallic raceway
and is isolated from possible contact
by a minimum cover of 450 mm (18 in.)
to any part of the elbow or is encased
in not less than 50 mm (2 in.) of
concrete.
250.94 Bonding for Other Systems. An
accessible means external to
enclosures for connecting intersystem
bonding and grounding electrode
conductors shall be provided at the
service equipment and at the
2008 NEC
Change Description and Impact to
Worker Safety
ground
(2) Are in runs of less than 7.5 m
(25 ft)
(3) Are free from probable contact
with ground, grounded metal, metal
lath, or other conductive material
(4) Are guarded against contact by
persons
Exception No. 2: Short sections of
metal enclosures or raceways used to
provide support or protection of cable
assemblies from physical damage shall
not be required to be connected to the
equipment grounding conductor.
Exception No. 3: A metal elbow shall
not be required to be connected to the
equipment grounding conductor where
it is installed in a nonmetallic raceway
and is isolated from possible contact
by a minimum cover of 450 mm (18 in.)
to any part of the elbow or is encased
in not less than 50 mm (2 in.) of
concrete.
250.94 Bonding for Other Systems. An
intersystem bonding termination for
connecting intersystem bonding and
grounding conductors required for
other systems shall be provided
external to enclosures at the service
Page 65 of 361
Modified to address the specific
requirements for intersystem
connections and to eliminate confusion
and misapplication of the requirements
intended.
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disconnecting means for any additional
buildings or structures by at least one
of the following means:
equipment and at the disconnecting
means for any additional buildings or
structures. The intersystem bonding
termination shall be accessible for
connection and inspection. The
intersystem bonding termination shall
have the capacity for connection of not
less than three intersystem bonding
conductors. The intersystem bonding
termination device shall not interfere
with opening a service or metering
equipment enclosure.
The intersystem bonding termination
shall be one of the following:
(1) Exposed nonflexible metallic
raceways
(2) Exposed grounding electrode
conductor
(3) Approved means for the external
connection of a copper or other
corrosion-resistant bonding or
grounding conductor to the grounded
raceway or equipment
(1) A set of terminals securely mounted
to the meter enclosure and electrically
connected to the meter enclosure.
The terminals shall be listed as
grounding and bonding equipment.
(2) A bonding bar near the service
equipment enclosure, meter enclosure,
or raceway for service conductors. The
bonding bar shall be connected with a
minimum 6 AWG copper conductor to
an equipment grounding conductor(s)
in the service equipment enclosure,
meter enclosure, or exposed
nonflexible metallic raceway.
(3) A bonding bar near the grounding
Page 66 of 361
Change Description and Impact to
Worker Safety
Actually improves worker safety by
assuring a continuous ground path.
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Change Description and Impact to
Worker Safety
electrode conductor. The bonding bar
shall be connected to the grounding
electrode conductor with a minimum 6
AWG copper conductor.
250.104 Bonding of Piping Systems
Exception: In existing buildings or
structures where any of the
intersystem bonding and grounding
conductors required by 770.93,
800.100(B), 810.21(F), 820.100(B),
830.100(B) exist, installation of the
intersystem bonding termination is not
required. An accessible means
external to enclosures for connecting
intersystem bonding and grounding
electrode conductors shall be
permitted at the service equipment
and at the disconnecting means for
any additional buildings or structures
by at least one of the following
means:
(1) Exposed nonflexible metallic
raceways
(2) An exposed grounding electrode
conductor
(3) Approved means for the external
connection of a copper or other
corrosion-resistant bonding or
grounding conductor to the
grounded raceway or equipment
250.104 Bonding of Piping Systems
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Added “based on the rating of the
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and Exposed Structural Steel.
(A) Metal Water Piping.
and Exposed Structural Steel.
(A) Metal Water Piping.
(2) Buildings of Multiple Occupancy. In
buildings of multiple occupancy where
the metal water piping system(s)
installed in or attached to a building or
structure for the individual occupancies
is metallically isolated from all other
occupancies by use of nonmetallic
water piping, the metal water piping
system(s) for each occupancy shall be
permitted to be bonded to the
equipment grounding terminal of the
panelboard or switchboard enclosure
(other than service equipment)
supplying that occupancy. The bonding
jumper shall be sized in accordance
with Table 250.122.
VI. Equipment Grounding and
Equipment Grounding Conductors
(2) Buildings of Multiple Occupancy. In
buildings of multiple occupancy where
the metal water piping system(s)
installed in or attached to a building or
structure for the individual occupancies
is metallically isolated from all other
occupancies by use of nonmetallic
water piping, the metal water piping
system(s) for each occupancy shall be
permitted to be bonded to the
equipment grounding terminal of the
panelboard or switchboard enclosure
(other than service equipment)
supplying that occupancy. The bonding
jumper shall be sized in accordance
with Table 250.122, based on the
rating of the overcurrent protective
device for the circuit supplying the
occupancy.
VI. Equipment Grounding and
Equipment Grounding Conductors
250.110 Equipment Fastened in Place
or Connected by Permanent Wiring
Methods (Fixed). Exposed non–
current-carrying metal parts of fixed
equipment likely to become energized
shall be grounded under any of the
250.110 Equipment Fastened in Place
or Connected by Permanent Wiring
Methods (Fixed). Exposed non–
current-carrying metal parts of fixed
equipment likely to become energized
shall be connected to the equipment
Page 68 of 361
Change Description and Impact to
Worker Safety
overcurrent protective device for the
circuit supplying the occupancy” to
clarify the intent to use the supply
conductor overcurrent protective
device rating for sizing the bonding
jumper.
Actually improves worker safety by
assuring a continuous ground path.
Replaced “grounded” with “connected
to the equipment grounding conductor”
in keeping with the overall emphasis
on the connection for the grounding
conductors and where the connection
is to be made.
Actually improves worker safety by
assuring a continuous ground path.
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grounding conductor under any of the
following conditions:
250.112 Fastened in Place or
250.112 Fastened in Place or
Connected by Permanent Wiring
Connected by Permanent Wiring
Methods (Fixed) — Specific. Exposed, Methods (Fixed) — Specific. Except as
non current-carrying metal parts of the permitted in 250.112(I), exposed, non
kinds of equipment described in
current-carrying metal parts of the
250.112(A) through (K), and non–
kinds of equipment described in
current-carrying metal parts of
250.112(A) through (K), and non–
equipment and enclosures described in current-carrying metal parts of
250.112(L) and (M), shall be grounded equipment and enclosures described in
regardless of voltage.
250.112(L) and (M), shall be
connected to the equipment grounding
conductor regardless of voltage.
Change Description and Impact to
Worker Safety
following conditions:
250.112 Fastened in Place or
Connected by Permanent Wiring
Methods (Fixed) — Specific.
(I) Power-Limited Remote-Control,
Signaling, and Fire Alarm Circuits.
Equipment supplied by Class 1 power
limited circuits and Class 1, Class 2,
and Class 3 remote control and
signaling circuits, and by fire alarm
circuits, shall be grounded where
system grounding is required by
Part II or Part VIII of this article.
250.112 Fastened in Place or
Connected by Permanent Wiring
Methods (Fixed) — Specific.
(I) Remote-Control, Signaling, and Fire
Alarm Circuits. Equipment supplied by
Class 1 circuits shall be grounded
unless operating at less than 50 volts.
Equipment supplied by Class 1 powerlimited circuits, by Class 2 and Class 3
remote-control and signaling circuits,
and by fire alarm circuits shall be
grounded where system grounding is
required by Part II or Part VIII of this
article.
Page 69 of 361
Replaced “grounded” with “connected
to the equipment grounding conductor”
in keeping with the overall emphasis
on the connection for the grounding
conductors and where the connection
is to be made.
The addition of the exception in
250.112(I) refers to Remote-Control,
Signaling, and Fire Alarm Circuits and
the less than 50 volts exception to
grounding requirements.
Actually improves worker safety by
assuring a continuous ground path.
Inserted the qualifier for Class 1 circuit
grounding requirements and to
separate the power limited Class 1
circuit requirements from other Class 1
circuits. The 50 volt threshold to align
with system voltage levels requiring
system grounding.
As Safe or Safer.
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250.112 Fastened in Place or
Connected by Permanent Wiring
Methods (Fixed) — Specific.
250.112 Fastened in Place or
Connected by Permanent Wiring
Methods (Fixed) — Specific.
(K) Skid Mounted Equipment.
Permanently mounted electrical
equipment and skids shall be grounded
with an equipment bonding jumper
sized as required by 250.122.
(K) Skid-Mounted Equipment.
Permanently mounted electrical
equipment and skids shall be
connected to the equipment grounding
conductor sized as required by
250.122.
250.112 Fastened in Place or
Connected by Permanent Wiring
Methods (Fixed) — Specific.
250.112 Fastened in Place or
Connected by Permanent Wiring
Methods (Fixed) — Specific.
(M) Metal Well Casings. Where a
submersible pump is used in a metal
well casing, the well casing shall be
bonded to the pump circuit equipment
grounding conductor.
250.114 Equipment Connected by
Cord and Plug. Under any of the
conditions described in 250.114(1)
through (4), exposed non–currentcarrying metal parts of cord-and plugconnected equipment likely to become
energized shall be grounded.
250.116 Non electric Equipment. The
metal parts of non electric equipment
(M) Metal Well Casings. Where a
submersible pump is used in a metal
well casing, the well casing shall be
connected to the pump circuit
equipment grounding conductor.
250.114 Equipment Connected by
Cord and Plug. Under any of the
conditions described in 250.114(1)
through (4), exposed non–currentcarrying metal parts of cord-and plugconnected equipment likely to become
energized shall be connected to the
equipment grounding conductor.
250.116 Non electrical Equipment. The
metal parts of the following non
Page 70 of 361
Change Description and Impact to
Worker Safety
Replaced “grounded” with “connected
to the equipment grounding conductor”
in keeping with the overall emphasis
on the connection for the grounding
conductors and where the connection
is to be made.
Actually improves worker safety by
assuring a continuous ground path.
Differentiates connected from bonding
to continue the emphasis on making
the proper connection.
As Safe or Safer.
Replaced “grounded” with “connected
to the equipment grounding conductor”
in keeping with the overall emphasis
on the connection for the grounding
conductors and where the connection
is to be made. This phrase was added
to each of the exceptions as well.
Actually improves worker safety by
assuring a continuous ground path.
Replaced “grounded” with “connected
to the equipment grounding conductor”
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described in this section shall be
grounded.
electrical equipment described in this
section shall be connected to the
equipment grounding conductor:
(1) Frames and tracks of electrically
operated cranes and hoists
(2) Frames of non electrically driven
elevator cars to which electric
conductors are attached
(3) Hand-operated metal shifting ropes
or cables of electric elevators
250.119 Identification of Equipment
Grounding Conductors. Unless
required elsewhere in this Code,
equipment grounding conductors shall
be permitted to be bare, covered, or
insulated. Individually covered or
insulated equipment grounding
conductors shall have a continuous
outer finish that is either green or
green with one or more yellow stripes
except as permitted in this section.
Conductors with insulation or individual
covering that is green, green with one
or more yellow stripes, or otherwise
identified as permitted by this section
shall not be used for ungrounded or
grounded circuit conductors.
(1) Frames and tracks of electrically
operated cranes and hoists
(2) Frames of non electrically driven
elevator cars to which electrical
conductors are attached
(3) Hand-operated metal shifting ropes
or cables of electric elevators
250.119 Identification of Equipment
Grounding Conductors. Unless
required elsewhere in this Code,
equipment grounding conductors shall
be permitted to be bare, covered, or
insulated. Individually covered or
insulated equipment grounding
conductors shall have a continuous
outer finish that is either green or
green with one or more yellow stripes
except as permitted in this section.
Conductors with insulation or individual
covering that is green, green with one
or more yellow stripes, or otherwise
identified as permitted by this section
shall not be used for ungrounded or
grounded circuit conductors.
Exception: Power-limited, Class 2 or
Class 3 circuit cables containing only
Page 71 of 361
Change Description and Impact to
Worker Safety
in keeping with the overall emphasis
on the connection for the grounding
conductors and where the connection
is to be made.
Actually improves worker safety by
assuring a continuous ground path.
Exception added to allow for the use of
green insulation within cables for
Power Limited Class 2 or Class 3
circuits.
As Safe or Safer.
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250.119 Identification of Equipment
Grounding Conductors.
circuits operating at less than 50 volts
shall be permitted to use a conductor
with green insulation for other than
equipment grounding purposes.
250.119 Identification of Equipment
Grounding Conductors.
(A) Conductors Larger Than 6 AWG.
Equipment grounding conductors
larger than 6 AWG shall comply with
250.119(A)(1) and (A)(2).
(A) Conductors Larger Than 6 AWG.
Equipment grounding conductors
larger than 6 AWG shall comply with
250.119(A)(1) and (A)(2).
(2) Identification shall encircle the
conductor and shall be accomplished
by one of the following:
a. Stripping the insulation or
covering from the entire exposed
length
b. Coloring the exposed insulation or
covering green
c. Marking the exposed insulation or
covering with green tape or green
adhesive labels
250.122 Size of Equipment Grounding
Conductors.
(2) Identification shall encircle the
conductor and shall be accomplished
by one of the following:
a. Stripping the insulation or
covering from the entire exposed
length
b. Coloring the insulation or
covering green at the termination
c. Marking the insulation or covering
with green tape or green adhesive
labels at the termination
250.122 Size of Equipment Grounding
Conductors.
(A) General. Copper, aluminum, or
copper-clad aluminum equipment
grounding conductors of the wire type
shall not be smaller than shown in
Table 250.122 but shall not be required
(A) General. Copper, aluminum, or
copper-clad aluminum equipment
grounding conductors of the wire type
shall not be smaller than shown in
Table 250.122, but in no case shall
Page 72 of 361
Change Description and Impact to
Worker Safety
Added “at the termination” to
specifically identify where the coloring
is required.
As Safe or Safer.
Emphasizes the size limitation to the
circuit conductor size and adds cable
tray to the equipment grounding
conductor allowances.
As Safe or Safer.
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to be larger than the circuit conductors
supplying the equipment. Where a
raceway or a cable armor or sheath is
used as the equipment grounding
conductor, as provided in 250.118 and
250.134(A), it shall comply with
250.4(A)(5) or (B)(4).
they be required to be larger than the
circuit conductors supplying the
equipment. Where a cable tray, a
raceway, or a cable armor or sheath is
used as the equipment grounding
conductor, as provided in 250.118 and
250.134(A), it shall comply with
250.4(A)(5) or (B)(4).
250.122 Size of Equipment Grounding
Conductors.
250.122 Size of Equipment Grounding
Conductors.
(C) Multiple Circuits. Where a single
equipment grounding conductor is run
with multiple circuits in the same
raceway or cable, it shall be sized for
the largest overcurrent device
protecting conductors in the raceway
or cable.
250.122 Size of Equipment Grounding
Conductors.
(D) Motor Circuits. Where the
overcurrent device consists of an
instantaneous trip circuit breaker or a
motor short-circuit protector, as
allowed in 430.52, the equipment
grounding conductor size shall be
(C) Multiple Circuits. Where a single
equipment grounding conductor is run
with multiple circuits in the same
raceway, cable, or cable tray, it shall
be sized for the largest overcurrent
device protecting conductors in the
raceway, cable, or cable tray.
Equipment grounding conductors
installed in cable trays shall meet the
minimum requirements of
392.3(B)(1)(c).
250.122 Size of Equipment Grounding
Conductors.
(D) Motor Circuits. Equipment
grounding conductors for motor circuits
shall be sized in accordance with
(D)(1) or (D)(2).
(1) General. The equipment grounding
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Change Description and Impact to
Worker Safety
Provides specific requirements for
sizing equipment grounding conductor
for multiple circuits and adds cable
trays as a method for routing multiple
circuits.
As Safe or Safer.
Provides specific requirements for
sizing equipment grounding
conductors for motor circuits and
eliminates the previous confusion
levels.
As Safe or Safer.
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permitted to be based on the rating of
the motor overload protective device
but shall not be less than the size
shown in Table 250.122.
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Change Description and Impact to
Worker Safety
conductor size shall not be smaller
than determined by 250.122(A) based
on the rating of the branch-circuit
short-circuit and ground fault protective
device.
(2) Instantaneous-Trip Circuit Breaker
and Motor Short-Circuit Protector.
Where the overcurrent device is an
instantaneous-trip circuit breaker or a
motor short-circuit protector, the
equipment grounding conductor shall
be sized not smaller than that given by
250.122(A) using the maximum
permitted rating of a dual element timedelay fuse selected for branch-circuit
short-circuit and ground-fault protection
in accordance with 430.52(C)(1),
Exception No. 1.
250.122 Size of Equipment Grounding 250.122 Size of Equipment Grounding Deleted the portions of this section that
Conductors.
Conductors.
presented qualifiers that were
misinterpreted and introduced
(F) Conductors in Parallel. Where
(F) Conductors in Parallel. Where
confusion into equipment grounding
conductors are run in parallel in
conductors are run in parallel in
conductor sizing. It simply points to
multiple raceways or cables as
multiple raceways or cables as
Table 250.122 for all cases.
permitted in 310.4, the equipment
permitted in 310.4, the equipment
grounding conductors, where used,
grounding conductors, where used,
As Safe or Safer.
shall be run in parallel in each raceway shall be run in parallel in each raceway
or cable.
or cable.
One of the methods in 250.122(F)(1) or 
(F)(2) shall be used to ensure the
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equipment grounding conductors are
protected.
(1) Based on Rating of Overcurrent
Protective Device.
Each parallel equipment grounding
conductor shall be sized on the basis
of the ampere rating of the overcurrent
device protecting the circuit conductors
in the raceway or cable in accordance
with Table 250.122.
Each parallel equipment grounding
conductor shall be sized on the basis
of the ampere rating of the overcurrent
device protecting the circuit conductors
in the raceway or cable in accordance
with Table 250.122.
(2) Ground-Fault Protection of

Equipment Installed. Where groundfault protection of equipment is
installed, each parallel equipment
grounding conductor in a
multiconductor cable shall be permitted
to be sized in accordance with Table
250.122 on the basis of the trip rating
of the ground-fault protection where
the following conditions are met:
(1) Conditions of maintenance and
supervision ensure that only
qualified persons will service the
installation.
(2) The ground-fault protection
equipment is set to trip at not more
than the ampacity of a single
ungrounded conductor of one of the
cables in parallel.
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Change Description and Impact to
Worker Safety
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(3) The ground-fault protection is
listed for the purpose of protecting
the equipment grounding conductor.
250.132 Short Sections of Raceway.
Isolated sections of metal raceway or
cable armor, where required to be
grounded, shall be grounded in
accordance with 250.134.
250.134 Equipment Fastened in Place
or Connected by Permanent Wiring
Methods (Fixed) — Grounding. Unless
grounded by connection to the
grounded circuit conductor as
permitted by 250.32, 250.140, and
250.142, non-current-carrying metal
parts of equipment, raceways, and
other enclosures, if grounded, shall be
grounded by one of the following
methods.
2008 NEC
250.132 Short Sections of Raceway.
Isolated sections of metal raceway or
cable armor, where required to be
grounded, shall be connected to an
equipment grounding conductor in
accordance with 250.134.
250.134 Equipment Fastened in Place
or Connected by Permanent Wiring
Methods (Fixed) — Grounding.
250.134 Equipment Fastened in Place
or Connected by Permanent Wiring
Methods (Fixed) — Grounding. Unless
grounded by connection to the
grounded circuit conductor as
permitted by 250.32, 250.140, and
250.142, non-current-carrying metal
parts of equipment, raceways, and
other enclosures, if grounded, shall be
connected to an equipment grounding
conductor by one of the methods
specified in 250.134(A) or (B).
250.134 Equipment Fastened in Place
or Connected by Permanent Wiring
Methods (Fixed) — Grounding.
(A) Equipment Grounding Conductor
Types. By any of the equipment
grounding conductors permitted by
(A) Equipment Grounding Conductor
Types. By connecting to any of the
equipment grounding conductors
Page 76 of 361
Change Description and Impact to
Worker Safety
Replaced “grounded” with “connected
to an equipment grounding conductor”
in keeping with the overall emphasis
on the connection for the grounding
conductors and where the connection
is to be made.
Actually improves worker safety by
assuring a continuous ground path.
Replaced “grounded” with “connected
to an equipment grounding conductor”
in keeping with the overall emphasis
on the connection for the grounding
conductors and where the connection
is to be made.
Actually improves worker safety by
assuring a continuous ground path.
Continuing the emphasis on the
connection to an equipment grounding
conductor versus simply grounding.
Actually improves worker safety by
assuring a continuous ground path.
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250.118.
permitted by 250.118.
(B) With Circuit Conductors. By an
equipment grounding conductor
contained within the same raceway,
cable, or otherwise run with the circuit
conductors.
250.136 Equipment Considered
Effectively Grounded. Under the
conditions specified in 250.136(A) and
(B), the non–current-carrying metal
parts of the equipment shall be
considered effectively grounded.
(B) With Circuit Conductors. By
connecting to an equipment grounding
conductor contained within the same
raceway, cable, or otherwise run with
the circuit conductors.
250.136 Equipment Considered
Grounded. Under the conditions
specified in 250.136(A) and (B), the
normally non–current-carrying metal
parts of the equipment shall be
considered grounded.
(A) Equipment Secured to Grounded
Metal Supports. Electrical equipment
secured to and in electrical contact
with a metal rack or structure provided
for its support and grounded by one of
the means indicated in 250.134. The
structural metal frame of a building
shall not be used as the required
equipment grounding conductor for ac
equipment.
(A) Equipment Secured to Grounded
Metal Supports. Electrical equipment
secured to and in electrical contact
with a metal rack or structure provided
for its support and connected to an
equipment grounding conductor by one
of the means indicated in 250.134. The
structural metal frame of a building
shall not be used as the required
equipment grounding conductor for ac
equipment.
(B) Metal Car Frames. Metal car
frames supported by metal hoisting
cables attached to or running over
metal sheaves or drums of elevator
machines that are grounded by one of
(B) Metal Car Frames. Metal car
frames supported by metal hoisting
cables attached to or running over
metal sheaves or drums of elevator
machines that are connected to an
Page 77 of 361
Change Description and Impact to
Worker Safety
Removed the term “effectively” and
continues the emphasis on the
connection to an equipment grounding
conductor versus simply grounding.
Actually improves worker safety by
assuring a continuous ground path.
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the methods indicated in 250.134.
250.138 Cord-and-Plug-Connected
Equipment. Non–current-carrying
metal parts of cord-and-plugconnected equipment, if grounded,
shall be grounded by one of the
methods in 250.138(A) or (B).
(B) By Means of a Separate Flexible
Wire or Strap. By means of a separate
flexible wire or strap, insulated or bare,
protected as well as practicable
against physical damage, where part of
equipment.
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equipment grounding conductor by one
of the methods indicated in 250.134.
250.138 Cord-and-Plug-Connected
Equipment. Non–current-carrying
metal parts of cord-and-plugconnected equipment, if grounded,
shall be connected to an equipment
grounding conductor by one of the
methods in 250.138(A) or (B).
250.144 Multiple Circuit Connections.
Where equipment is required to be
grounded and is supplied by separate
connection to more than one circuit or
grounded premises wiring system, a
means for grounding shall be provided
for each such connection as specified
in 250.134 and 250.138.
(B) By Means of a Separate Flexible
Wire or Strap. By means of a separate
flexible wire or strap, insulated or bare,
connected to an equipment grounding
conductor, and protected as well as
practicable against physical damage,
where part of equipment.
250.144 Multiple Circuit Connections.
Where equipment is grounded and is
supplied by separate connection to
more than one circuit or grounded
premises wiring system, an equipment
grounding conductor termination shall
be provided for each such connection
as specified in 250.134 and 250.138.
250.146 Connecting Receptacle
Grounding Terminal to Box. An
equipment bonding jumper shall be
used to connect the grounding terminal
of a grounding-type receptacle to a
250.146 Connecting Receptacle
Grounding Terminal to Box. An
equipment bonding jumper shall be
used to connect the grounding terminal
of a grounding-type receptacle to a
Page 78 of 361
Change Description and Impact to
Worker Safety
Continuing the emphasis on the
connection to an equipment grounding
conductor versus simply grounding.
Actually improves worker safety by
assuring a continuous ground path.
Replaced “a means for grounding“ with
“an equipment grounding conductor
termination” to continue the emphasis
of connections to the equipment
grounding conductor versus just
“grounding.”
Actually improves worker safety by
assuring a continuous ground path.
Added the sizing requirements for the
equipment bonding jumper.
As Safe or Safer.
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grounded box unless grounded as in
250.146(A) through (D).
250.146 Connecting Receptacle
Grounding Terminal to Box.
(A) Surface Mounted Box. Where the
box is mounted on the surface, direct
metal-to-metal contact between the
device yoke and the box or a contact
yoke or device that complies with
250.146(B) shall be permitted to
ground the receptacle to the box. At
least one of the insulating washers
shall be removed from receptacles that
do not have a contact yoke or device
that complies with 250.146(B) to
ensure direct metal-to-metal contact.
This provision shall not apply to covermounted receptacles unless the box
and cover combination are listed as
providing satisfactory ground continuity
between the box and the receptacle.
2008 NEC
grounded box unless grounded as in
250.146(A) through (D). The
equipment bonding jumper shall be
sized in accordance with Table
250.122 based on the rating of the
overcurrent device protecting the
circuit conductors.
250.146 Connecting Receptacle
Grounding Terminal to Box.
(A) Surface-Mounted Box. Where the
box is mounted on the surface, direct
metal-to-metal contact between the
device yoke and the box or a contact
yoke or device that complies with
250.146(B) shall be permitted to
ground the receptacle to the box. At
least one of the insulating washers
shall be removed from receptacles that
do not have a contact yoke or device
that complies with 250.146(B) to
ensure direct metal-to-metal contact.
This provision shall not apply to covermounted receptacles unless the box
and cover combination are listed as
providing satisfactory ground continuity
between the box and the receptacle. A
listed exposed work cover shall be
permitted to be the grounding and
bonding means when (1) the device is
attached to the cover with at least two
Page 79 of 361
Change Description and Impact to
Worker Safety
Added the use of listed covers as the
grounding and bonding means.
As Safe or Safer.
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250.146 Connecting Receptacle
Grounding Terminal to Box.
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fasteners that are permanent (such as
a rivet) or have a thread locking or
screw locking means and (2) when the
cover mounting holes are located on a
flat non-raised portion of the cover.
250.146 Connecting Receptacle
Grounding Terminal to Box.
Change Description and Impact to
Worker Safety
Continuing the emphasis on the
connection to an equipment grounding
conductor versus simply grounding.
(D) Isolated Receptacles. Where
(D) Isolated Receptacles. Where
For isolated receptacles, the
required for the reduction of electrical
installed for the reduction of electrical
installation of the equipment grounding
noise (electromagnetic interference) on noise (electromagnetic interference) on conductor meeting the requirements of
the grounding circuit, a receptacle in
the grounding circuit, a receptacle in
this section will be allowed to pass
which the grounding terminal is
which the grounding terminal is
through unconnected.
purposely insulated from the
purposely insulated from the
receptacle mounting means shall be
receptacle mounting means shall be
Actually improves worker safety by
permitted. The receptacle grounding
permitted. The receptacle grounding
assuring a continuous ground path.
terminal shall be grounded by an
terminal shall be connected to an
insulated equipment grounding
insulated equipment grounding
conductor run with the circuit
conductor run with the circuit
conductors. This grounding conductor
conductors. This equipment grounding
shall be permitted to pass through one conductor shall be permitted to pass
or more panelboards without
through one or more panelboards
connection to the panelboard
without a connection to the panelboard
grounding terminal as permitted in
grounding terminal bar as permitted in
408.40, Exception, so as to terminate
408.40, Exception, so as to terminate
within the same building or structure
within the same building or structure
directly at an equipment grounding
directly at an equipment grounding
conductor terminal of the applicable
conductor terminal of the applicable
derived system or service.
derived system or service. Where
installed in accordance with the
provisions of this section, this
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250.148 Continuity and Attachment of
Equipment Grounding Conductors to
Boxes. Where circuit conductors are
spliced within a box, or terminated on
equipment within or supported by a
box, any equipment grounding
conductor(s) associated with those
circuit conductors shall be spliced or
joined within the box or to the box with
devices suitable for the use in
accordance with 250.148(A) through
(E).
250.148 Continuity and Attachment of
Equipment Grounding Conductors to
Boxes.
(C) Metal Boxes. A connection shall be
made between the one or more
equipment grounding conductors and a
metal box by means of a grounding
screw that shall be used for no other
purpose or a listed grounding device.
250.166 Size of Direct-Current
Grounding Electrode Conductor. The
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equipment grounding conductor shall
also be permitted to pass through
boxes, wireways, or other enclosures
without being connected to such
enclosures.
250.148 Continuity and Attachment of
Equipment Grounding Conductors to
Boxes. Where circuit conductors are
spliced within a box, or terminated on
equipment within or supported by a
box, any equipment grounding
conductor(s) associated with those
circuit conductors shall be connected
within the box or to the box with
devices suitable for the use in
accordance with 250.148(A) through
(E).
250.148 Continuity and Attachment of
Equipment Grounding Conductors to
Boxes.
Change Description and Impact to
Worker Safety
Emphasis on connection.
Actually improves worker safety by
assuring a continuous ground path.
Added “equipment listed for grounding”
to the approved methods to allow for
the listing of new equipment.
(C) Metal Boxes. A connection shall be As Safe or Safer.
made between the one or more
equipment grounding conductors and a
metal box by means of a grounding
screw that shall be used for no other
purpose, equipment listed for
grounding, or a listed grounding
device.
250.166 Size of the Direct-Current
Separates the requirements from the
Grounding Electrode Conductor. The
permitted variations.
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size of the grounding electrode
conductor for a dc system shall be as
specified in 250.166(A) through (E).
2008 NEC
IX. Instruments, Meters, and Relays
size of the grounding electrode
conductor for a dc system shall be as
specified in 250.166(A) and (B), except
as permitted by 250.166(C) through
(E).
250.168 Direct-Current System
Bonding Jumper. For direct-current
systems that are to be grounded, an
unspliced bonding jumper shall be
used to connect the equipment
grounding conductor(s) to the
grounded conductor at the source or
the first system disconnecting means
where the system is grounded. The
size of the bonding jumper shall not be
smaller than the system grounding
electrode conductor specified in
250.166 and shall comply with the
provisions of 250.28(A), (B), and (C).
IX. Instruments, Meters, and Relays
250.170 Instrument Transformer
Circuits. Secondary circuits of current
and potential instrument transformers
shall be grounded where the primary
windings are connected to circuits of
300 volts or more to ground and,
where on switchboards, shall be
grounded irrespective of voltage.
250.170 Instrument Transformer
Circuits. Secondary circuits of current
and potential instrument transformers
shall be grounded where the primary
windings are connected to circuits of
300 volts or more to ground and,
where on switchboards, shall be
grounded irrespective of voltage.
Exception: Circuits where the primary
Exception No. 1: Circuits where the
250.168 Direct-Current Bonding
Jumper. For dc systems, the size of
the bonding jumper shall not be
smaller than the system grounding
electrode conductor specified in
250.166.
Page 82 of 361
Change Description and Impact to
Worker Safety
As Safe or Safer.
Specifically targets the requirements
for the system bonding conductor to
eliminate confusion as to just what or
where the connection is to be made.
Actually improves worker safety by
assuring a continuous ground path.
Added exception for the three phase
systems connected in delta where
there would be no need for grounding.
As Safe or Safer.
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windings are connected to circuits of
less than 1000 volts with no live parts
or wiring exposed or accessible to
other than qualified persons.
250.172 Instrument Transformer
Cases. Cases or frames of instrument
transformers shall be grounded where
accessible to other than qualified
persons.
250.174 Cases of Instruments, Meters,
and Relays Operating at Less Than
1000 Volts. Instruments, meters, and
relays operating with windings or
working parts at less than 1000 volts
shall be grounded as specified in
250.174(A), (B), or (C).
(A) Not on Switchboards. Instruments,
meters, and relays not located on
switchboards, operating with windings
2008 NEC
Change Description and Impact to
Worker Safety
primary windings are connected to
circuits of less than 1000 volts with no
live parts or wiring exposed or
accessible to other than qualified
persons.
Exception No. 2: Current transformer
secondaries connected in a threephase delta configuration shall not be
required to be grounded.
250.172 Instrument Transformer
Cases. Cases or frames of instrument
transformers shall be connected to the
equipment grounding conductor where
accessible to other than qualified
persons.
250.174 Cases of Instruments, Meters,
and Relays Operating at Less Than
1000 Volts. Instruments, meters, and
relays operating with windings or
working parts at less than 1000 volts
shall be connected to the equipment
grounding conductor as specified in
250.174(A), (B), or (C).
(A) Not on Switchboards. Instruments,
meters, and relays not located on
switchboards, operating with windings
Page 83 of 361
Replaced “grounded“ with “connected
to the equipment grounding conductor”
to continue the emphasis of
connections to the equipment
grounding conductor versus just
“grounding.”
Actually improves worker safety by
assuring a continuous ground path.
Replaced “grounded“ with “connected
to the equipment grounding conductor”
to continue the emphasis of
connections to the equipment
grounding conductor versus just
“grounding.”
Actually improves worker safety by
assuring a continuous ground path.
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or working parts at 300 volts or more to
ground, and accessible to other than
qualified persons, shall have the cases
and other exposed metal parts
grounded.
or working parts at 300 volts or more to
ground, and accessible to other than
qualified persons, shall have the cases
and other exposed metal parts
connected to the equipment grounding
conductor.
(B) On Dead-Front Switchboards.
Instruments, meters, and relays
(whether operated from current and
potential transformers or connected
directly in the circuit) on switchboards
having no live parts on the front of the
panels shall have the cases grounded.
(B) On Dead-Front Switchboards.
Instruments, meters, and relays
(whether operated from current and
potential transformers or connected
directly in the circuit) on switchboards
having no live parts on the front of the
panels shall have the cases connected
to the equipment grounding conductor.
(C) On Live-Front Switchboards.
Instruments, meters, and relays
(whether operated from current and
potential transformers or connected
directly in the circuit) on switchboards
having exposed live parts on the front
of panels shall not have their cases
grounded. Mats of insulating rubber or
other suitable floor insulation shall be
provided for the operator where the
voltage to ground exceeds 150.
(C) On Live-Front Switchboards.
Instruments, meters, and relays
(whether operated from current and
potential transformers or connected
directly in the circuit) on switchboards
having exposed live parts on the front
of panels shall not have their cases
connected to the equipment grounding
conductor. Mats of insulating rubber or
other suitable floor insulation shall be
provided for the operator where the
voltage to ground exceeds 150.
250.176 Cases of Instruments, Meters,
and Relays — Operating Voltage 1 kV
and Over. Where instruments, meters,
250.176 Cases of Instruments, Meters,
and Relays — Operating Voltage 1 kV
and Over. Where instruments, meters,
Page 84 of 361
Change Description and Impact to
Worker Safety
Replaced “grounded“ with “connected
to the equipment grounding
conductor”.
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and relays have current-carrying parts
of 1 kV and over to ground, they shall
be isolated by elevation or protected by
suitable barriers, grounded metal, or
insulating covers or guards. Their
cases shall not be grounded.
and relays have current-carrying parts
of 1 kV and over to ground, they shall
be isolated by elevation or protected by
suitable barriers, grounded metal, or
insulating covers or guards. Their
cases shall not be connected to the
equipment grounding conductor.
250.184 Solidly Grounded Neutral
250.184 Solidly Grounded Neutral
Systems. Solidly grounded neutral
Systems. Solidly grounded neutral
systems shall be permitted to be either systems shall be permitted to be either
single point grounded or multigrounded single point grounded or multigrounded
neutral.
neutral.
(A) Neutral Conductor.
(A) Neutral Conductor.
(1) Insulation Level. The minimum
insulation level for neutral conductors
of solidly grounded systems shall be
600 volts.
(1) Insulation Level. The minimum
insulation level for neutral conductors
of solidly grounded systems shall be
600 volts.
Exception No. 1: Bare copper
conductors shall be permitted to be
used for the neutral of service
entrances and the neutral of directburied portions of feeders.
Exception No. 1: Bare copper
conductors shall be permitted to be
used for the neutral conductor of the
following:
(1) Service-entrance conductors
(2) Service laterals
(3) Direct-buried portions of feeders.
Exception No. 2: Bare conductors
shall be permitted for the neutral
conductor of overhead portions
installed outdoors.
Exception No. 2: Bare conductors shall
be permitted for the neutral of
overhead portions installed outdoors.
Page 85 of 361
Change Description and Impact to
Worker Safety
As Safe or Safer.
Emphasizes neutral conductor and
provides specific requirements for use
of bare copper conductors.
As Safe or Safer.
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Exception No. 3: The neutral grounded
conductor shall be permitted to be a
bare conductor if isolated from phase
conductors and protected from
physical damage.
250.184 Solidly Grounded Neutral
Systems.
Exception No. 3: The grounded
neutral conductor shall be permitted
to be a bare conductor if isolated
from phase conductors and
protected from physical damage.
250.184 Solidly Grounded Neutral
Systems.
(B) Single Point Grounded System.
Where a single point grounded neutral
system is used, the following shall
apply:
(B) Single-Point Grounded Neutral
System. Where a single-point
grounded neutral system is used, the
following shall apply:
(1) A single point grounded system
shall be permitted to be supplied from
(a) or (b):
a. A separately derived system
b. A multigrounded neutral system
with an equipment grounding
conductor connected to the
multigrounded neutral at the source
of the single point grounded system
(1) A single-point grounded neutral
system shall be permitted
to be supplied from (a) or (b):
a. A separately derived system
b. A multigrounded neutral system
with an equipment grounding
conductor connected to the
multigrounded neutral conductor at
the source of the single-point
grounded neutral system
(2) A grounding electrode shall be
provided for the system.
(2) A grounding electrode shall be
provided for the system.
(3) A grounding electrode conductor
shall connect the grounding electrode
to the system neutral.
(3) A grounding electrode conductor
shall connect the grounding electrode
to the system neutral conductor.
Page 86 of 361
Change Description and Impact to
Worker Safety
Inserted “conductor” and “neutral” to
emphasize that it is the conductor
connection required for the system.
As Safe or Safer.
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2008 NEC
(4) A bonding jumper shall connect the
equipment grounding conductor to the
grounding electrode conductor.
(4) A bonding jumper shall connect the
equipment grounding conductor to the
grounding electrode conductor.
(5) An equipment bonding conductor
shall be provided to each building,
structure, and equipment enclosure.
(5) An equipment grounding conductor
shall be provided to each building,
structure, and equipment enclosure.
(6) A neutral shall only be required
where phase to neutral loads are
supplied.
(6) A neutral conductor shall only be
required where phase-to-neutral loads
are supplied.
(7) The neutral, where provided, shall
be insulated and isolated from earth
except at one location.
(7) The neutral conductor, where
provided, shall be insulated and
isolated from earth except at one
location.
(8) An equipment grounding conductor
shall be run with the phase conductors
and shall comply with (a), (b), and (c):
a. Shall not carry continuous load
b. May be bare or insulated
c. Shall have sufficient ampacity for
fault current duty
250.186 Impedance Grounded Neutral
Systems.
(8) An equipment grounding conductor
shall be run with the phase conductors
and shall comply with (a), (b), and (c):
a. Shall not carry continuous load
b. May be bare or insulated
c. Shall have sufficient ampacity for
fault current duty
250.186 Impedance Grounded Neutral
Systems.
(C) System Neutral Connection. The
system neutral shall not be connected
to ground, except through the neutral
(C) System Neutral Conductor
Connection. The system neutral
conductor shall not be connected to
Page 87 of 361
Change Description and Impact to
Worker Safety
Inserted “conductor” to emphasize that
it is the conductor connection required
for the system.
As Safe or Safer.
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grounding impedance.
250.188 Grounding of Systems
Supplying Portable or Mobile
Equipment. Systems supplying
portable or mobile high-voltage
equipment, other than substations
installed on a temporary basis, shall
comply with 250.188(A) through (F).
(A) Portable or Mobile Equipment.
Portable or mobile high-voltage
equipment shall be supplied from a
system having its neutral grounded
through an impedance. Where a deltaconnected high-voltage system is used
to supply portable or mobile
equipment, a system neutral shall be
derived.
I. General
280.1 Scope. This article covers
general requirements, installation
requirements, and connection
requirements for surge arresters
installed on premises wiring systems.
280.2 Definition.
Surge Arrester. A protective device for
2008 NEC
ground, except through the neutral
grounding impedance.
250.188 Grounding of Systems
Supplying Portable or Mobile
Equipment. Systems supplying
portable or mobile high-voltage
equipment, other than substations
installed on a temporary basis, shall
comply with 250.188(A) through (F).
(A) Portable or Mobile Equipment.
Portable or mobile high-voltage
equipment shall be supplied from a
system having its neutral conductor
grounded through an impedance.
Where a delta-connected high-voltage
system is used to supply portable or
mobile equipment, a system neutral
point and associated neutral conductor
shall be derived.
Article 280
I. General
280.1 Scope. This article covers
general requirements, installation
requirements, and connection
requirements for surge arresters
installed on premises wiring systems
over 1 kV.

Page 88 of 361
Change Description and Impact to
Worker Safety
Inserted “conductor” and “point and
associated neutral conductor” to
emphasize that it is the conductor
connection required for the system.
As Safe or Safer.
Redefinition of scope of the article to
only apply to systems over 1kV.
Actually provides increased worker
safety by requiring application of surge
protectors where they will not
catastrophically fail endangering
workers.
Definition moved to Article 100.
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2008 NEC
limiting surge voltages by discharging
or bypassing surge current, and it also
prevents continued flow of follow
current while remaining capable of
repeating these functions.
280.2 Uses Not Permitted. A surge
arrester shall not be installed where
the rating of the surge arrester is less
than the maximum continuous phaseto-ground power frequency voltage
available at the point of application.
280.4 Surge Arrester Selection.
(A) Circuits of Less Than 1000 Volts.
Surge arresters installed on a circuit of
less than 1000 volts shall comply with
all of the following:
280.4 Surge Arrester Selection. The
surge arresters shall comply with
280.4(A) and (B).
(1) The rating of the surge arrester
shall be equal to or greater than the
maximum continuous phase-toground power frequency voltage
available at the point of application.
(2) Surge arresters installed on
circuits of less than 1000 volts shall
be listed.
(3) Surge arresters shall be marked
with a short circuit current rating
and shall not be installed at a point
on the system where the available
fault current is in excess of that
rating.
(A) Rating. The rating of a surge
arrester shall be equal to or greater
than the maximum continuous
operating voltage available at the point
of application.
(1) Solidly Grounded Systems. The
maximum continuous operating
voltage shall be the phase-toground voltage of the system.
(2) Impedance or Ungrounded
System. The maximum continuous
operating voltage shall be the
phase-to-phase voltage of the
system.
Page 89 of 361
Change Description and Impact to
Worker Safety
Uses not permitted added to
specifically address the limitations of
surge arrester installations.
Actually provides increased worker
safety by requiring application of surge
protectors where they will not
catastrophically fail endangering
workers.
Changes necessitated by the
redefinition of the scope of the article.
Actually provides increased worker
safety by requiring application of surge
protectors where they will not
catastrophically fail endangering
workers.
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Change Description and Impact to
Worker Safety
(4) Surge arresters shall not be
installed on ungrounded systems,
impedance grounded systems, or
corner grounded delta systems
unless listed specifically for use on
these systems.
(B) Circuits of 1 kV and Over— Silicon
Carbide Types. The rating of a silicon
carbide-type surge arrester shall be not
less than 125 percent of the maximum
continuous phase-to-ground voltage
available at the point of application.
(B) Silicon Carbide Types. The rating
of a silicon carbide-type surge arrester
shall be not less than 125 percent of
the rating specified in 280.4(A).
280.5 Listing. A surge arrester shall be
a listed device.
280.12 Routing of Surge Arrester
Connections. The conductor used to
connect the surge arrester to line or
bus and to ground shall not be any
longer than necessary and shall avoid
unnecessary bends.
280.21 Installed at Services of Less
Than 1000 Volts.
Line and ground connecting
280.12 Routing of Surge Arrester
Grounding Conductors. The conductor
used to connect the surge arrester to
line, bus, or equipment and to a
grounding conductor connection point
as provided in 280.21 shall not be any
longer than necessary and shall avoid
unnecessary bends.
280.21 Connection.

New section developed as an outfall of
rewording 280.4.
Actually provides increased worker
safety.
Modified to specifically state the
requirements for connection of the
surge arrester to a specific grounding
conductor point versus just “ground.”
Actually provides increased worker
safety.
Reworded based on the redefinition of
Article 280 to only over 1kV systems.
As Safe or Safer.
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Change Description and Impact to
Worker Safety
conductors shall not be smaller than 14
AWG copper or 12 AWG aluminum.
The arrester grounding conductor shall
be connected to one of the following:
(1) Grounded service conductor
(2) Grounding electrode conductor
(3) Grounding electrode for the service
(4) Equipment grounding terminal in
the service equipment
280.22 Installed on the Load Side
Services of Less Than 1000 Volts. Line
and ground connecting conductors
shall not be smaller than 14 AWG
copper or 12 AWG aluminum. A surge
arrester shall be permitted to be
connected between any two
conductors — ungrounded
conductor(s), grounded conductor,
grounding conductor. The grounded
conductor and the grounding conductor
shall be interconnected only by the
normal operation of the surge arrester
during a surge.
280.23 Circuits of 1 kV and Over —
Surge-Arrester Conductors. The
conductor between the surge arrester
and the line and the surge arrester and
the grounding connection shall not be
smaller than 6 AWG copper or
aluminum.
The arrester grounding conductor shall
be connected to one of the following:
(1) Grounded service conductor
(2) Grounding electrode conductor
(3) Grounding electrode for the service
(4) Equipment grounding terminal in
the service equipment

Deleted based on the redefinition of
Article 280 to only over 1kV systems.
As Safe or Safer.
280.23 Surge-Arrester Conductors.
The conductor between the surge
arrester and the line and the surge
arrester and the grounding connection
shall not be smaller than 6 AWG
copper or aluminum.
Page 91 of 361
Reworded based on the redefinition of
Article 280 to only over 1kV systems.
As Safe or Safer.
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280.24 Circuits of 1 kV and Over —
Interconnections. The grounding
conductor of a surge arrester
protecting a transformer that supplies a
secondary distribution system shall be
interconnected as specified in
280.24(A), (B), or (C).
280.24 Circuits of 1 kV and Over —
Interconnections.
280.24 Interconnections. The
grounding conductor of a surge
arrester protecting a transformer that
supplies a secondary distribution
system shall be interconnected as
specified in 280.24(A), (B), or (C).
(A) Metallic Interconnections. A
metallic interconnection shall be made
to the secondary grounded circuit
conductor or the secondary circuit
grounding conductor provided that,
in addition to the direct grounding
connection at the surge arrester, the
following occurs:
(A) Metallic Interconnections.
(1) The grounded conductor of the
secondary has elsewhere a
grounding connection to a
continuous metal underground
water piping system. However, in
urban water-pipe areas where there
are at least four water-pipe
connections on the neutral and not
fewer than four such connections in
each mile of neutral, the metallic
interconnection shall be permitted
to be made to the secondary
280.24 Interconnections.
Change Description and Impact to
Worker Safety
Reworded based on the redefinition of
Article 280 to only over 1kV systems.
As Safe or Safer.
Modified to specifically address the
neutral conductor and that the
connection needs to comply with the
requirements set forth in the article.
(1) Additional Grounding
As Safe or Safer.
Connection. The grounded
conductor of the secondary has
elsewhere a grounding connection
to a continuous metal underground
water piping system. In urban waterpipe areas where there are at least
four water-pipe connections on the
neutral conductor and not fewer
than four such connections in each
mile of neutral conductor, the
metallic interconnection shall be
permitted to be made to the
secondary neutral conductor with
omission of the direct grounding
connection at the surge arrester.
(2) Multigrounded Neutral System
Connection. The grounded
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neutral with omission of the direct
grounding connection at the surge
arrester.
(2) The grounded conductor of the
secondary system is a part of a
multiground neutral system or static
wire of which the primary neutral or
static wire has at least four ground
connections in each mile of line in
addition to a ground at each
service.
280.25 Grounding. Except as indicated
in this article, surge arrester grounding
connections shall be made as specified
in Article 250. Grounding conductors
shall not be run in metal enclosures
unless bonded to both ends of such
enclosure.
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Change Description and Impact to
Worker Safety
conductor of the secondary system
is a part of a multigrounded neutral
system or static wire of which the
primary neutral conductor or static
wire has at least four grounding
connections in each mile of line in
addition to a grounding connection
at each service.
I. General
280.25 Grounding Conductor
Connections and Enclosures. Except
as indicated in this article, surgearrester grounding conductor
connections shall be made as specified
in Article 250, Parts III and X.
Grounding conductors installed in
metal enclosures shall comply with
250.64(E).
Article 285
I. General
285.1 Scope. This article covers
general requirements, installation
requirements, and connection
requirements for transient voltage
surge suppressors (TVSSs)
permanently installed on premises
wiring systems.
285.1 Scope. This article covers
general requirements, installation
requirements, and connection
As Safe or Safer.
requirements for SPDs [surge arresters
and transient voltage surge
suppressors (TVSSs)] permanently
installed on premises wiring systems 1
Page 93 of 361
Modified to address the importance of
the conductor connection and to point
to the specific requirements in Article
250 instead of the article in general.
This is partially due to the effort to
have all references to other articles
comply with the NFPA Style Manual.
As Safe or Safer.
Reworded based on the redefinition of
Article 285 to only less than 1kV
systems.
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285.2 Definition. Transient Voltage
Surge Suppressor (TVSS). A
protective device for limiting transient
voltages by diverting or limiting surge
current; it also prevents continued flow
of follow current while remaining
capable of repeating these functions.
285.3 Uses Not Permitted. A TVSS
device shall not be installed in the
following:
(1) Circuits exceeding 600 volts
(2) On ungrounded systems,
impedance grounded systems, or
corner grounded delta systems unless
listed specifically for use on these
systems.
(3) Where the rating of the TVSS is
less than the maximum continuous
phase-to-ground power frequency
voltage available at the point of
application
285.4 Number Required. Where used
at a point on a circuit, the TVSS shall
be connected to each ungrounded
conductor.
2008 NEC
kV or less.

Change Description and Impact to
Worker Safety
Definition incorporated into Article 100
Surge Protective Device (SPD).
As Safe or Safer.
285.3 Uses Not Permitted. An SPD
(surge arrester or TVSS) device shall
not be installed in the following:
(1) Circuits exceeding 1 kV
(2) On ungrounded systems,
impedance grounded systems, or
corner grounded delta systems unless
listed specifically for use on these
systems.
(3) Where the rating of the SPD (surge
arrester or TVSS) is less than the
maximum continuous phase-to-ground
power frequency voltage available at
the point of application
285.4 Number Required. Where used
at a point on a circuit, the SPD (surge
arrester or TVSS) shall be connected
to each ungrounded conductor.
Reworded based on the redefinition of
Article 285 to only less than 1kV
systems.
As Safe or Safer.
Reworded based on the redefinition of
Article 285 to only less than 1kV
systems.
As Safe or Safer.
285.5 Listing. A TVSS shall be a listed
device.
285.5 Listing. An SPD (surge arrester
or TVSS) shall be a listed device.
Page 94 of 361
Reworded based on the redefinition of
Article 285 to only less than 1kV
systems.
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Change Description and Impact to
Worker Safety
As Safe or Safer.
285.6 Short Circuit Current Rating. The
TVSS shall be marked with a short
circuit current rating and shall not be
installed at a point on the system
where the available fault current is in
excess of that rating. This marking
requirement shall not apply to
receptacles.
II. Installation
285.6 Short-Circuit Current Rating. The
SPD (surge arrester or TVSS) shall be
marked with a short-circuit current
rating and shall not be installed at a
point on the system where the
available fault current is in excess of
that rating. This marking requirement
shall not apply to receptacles.
II. Installation
285.11 Location. TVSSs shall be
permitted to be located indoors or
outdoors and shall be made
inaccessible to unqualified persons,
unless listed for installation in
accessible locations.
285.12 Routing of Connections. The
conductors used to connect the TVSS
to the line or bus and to ground shall
not be any longer than necessary and
shall avoid unnecessary bends.
285.11 Location. SPDs (surge
arresters or TVSSs) shall be permitted
to be located indoors or outdoors and
shall be made inaccessible to
unqualified persons, unless listed for
installation in accessible locations.
285.12 Routing of Connections. The
conductors used to connect the SPD
(surge arrester or TVSS) to the line or
bus and to ground shall not be any
longer than necessary and shall avoid
unnecessary bends.
III. Connecting SPDs.
III. Connecting Transient Voltage
Surge Suppressors
285.21 Connection. Where a TVSS is
installed, it shall comply with 285.21(A)
through (C).
285.21 Connection. Where an SPD
(surge arrester or TVSS) device is
installed, it shall comply with 285.23
Page 95 of 361
Reworded based on the redefinition of
Article 285 to only less than 1kV
systems.
As Safe or Safer.
Reworded based on the redefinition of
Article 285 to only less than 1kV
systems.
As Safe or Safer.
Reworded based on the redefinition of
Article 285 to only less than 1kV
systems.
As Safe or Safer.
Total rewrite based on the redefinition
of Article 285 to only less than 1kV
systems and to include SPD’s.
As Safe or Safer.
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through 285.28.
285.23 Type 1 SPDs (Surge
Arresters). Type 1 SPDs shall be
installed in accordance with 285.23(A)
and (B).
(A) Installation. Type 1 SPDs (surge
arresters) shall be installed as follows:
(1) Type 1 SPDs (surge arresters)
shall be permitted to be connected
to the supply side of the service
disconnect as permitted in 230.82(4)
or
(2) Type 1 SPDs (surge arresters)
shall be permitted to be connected
as specified in 285.24.
(B) At the Service. When installed at
services, the grounding conductor of a
Type 1 SPD shall be connected to one
of the following:
(1) Grounded service conductor
(2) Grounding electrode conductor
(3) Grounding electrode for the
service
(4) Equipment grounding terminal in
the service equipment
285.24 Type 2 SPDs (TVSSs). Type 2
SPDs (TVSSs) shall be installed in
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Change Description and Impact to
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accordance with 285.24(A) through
(C).
(A) Location.
(1) Service Supplied Building or
Structure. The transient voltage
surge suppressor shall be
connected on the load side of a
service disconnect overcurrent
device required in 230.91, unless
installed in accordance with
230.82(8).
(A) Service-Supplied Building or
Structure. Type 2 SPDs (TVSSs) shall
be connected anywhere on the load
side of a service disconnect
overcurrent device required in 230.91,
unless installed in accordance with
230.82(8).
(2) Feeder Supplied Building or
Structure. The transient voltage
surge suppressor shall be
connected on the load side of the
first overcurrent device at the
building or structure.
(B) Feeder-Supplied Building or
Structure. Type 2 SPDs (TVSSs) shall
be connected at the building or
structure anywhere on the load side of
the first overcurrent device at the
building or structure.
Exception to (1) and (2): Where the
TVSS is also listed as a surge
arrester, the connection shall be as
permitted by Article 280.
(3) Separately Derived System. The
TVSS shall be connected on the
load side of the first overcurrent
device in a separately derived
system.

(C) Separately Derived System. The
SPD (TVSS) shall be connected on the
load side of the first overcurrent device
in a separately derived system.
285.25 Type 3 SPDs. Type 3 SPDs
Page 97 of 361
Change Description and Impact to
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(TVSSs) shall be permitted to be
installed anywhere on the load side of
branch circuit overcurrent protection up
to the equipment served, provided the
connection is a minimum 10 m (30 ft)
of conductor distance from the service
or separately derived system
disconnect.
(B) Conductor Size. Line and ground
connecting conductors shall not be
smaller than 14 AWG copper or 12
AWG aluminum.
285.26 Conductor Size. Line and
grounding conductors shall not be
smaller than 14 AWG copper or 12
AWG aluminum.
(C) Connection Between Conductors.
A TVSS shall be permitted to be
connected between any two
conductors — ungrounded
conductor(s), grounded conductor,
grounding conductor. The grounded
conductor and the grounding conductor
shall be interconnected only by the
normal operation of the TVSS during a
surge.
285.27 Connection Between
Conductors. An SPD (surge arrester or
TVSS) shall be permitted to be
connected between any two
conductors — ungrounded
conductor(s), grounded conductor,
grounding conductor. The grounded
conductor and the grounding conductor
shall be interconnected only by the
normal operation of the SPD (surge
arrester or TVSS) during a surge.
285.28 Grounding Conductor
Connections and Enclosures.
Except as indicated in this article, SPD
grounding connections shall be made
as specified in Article 250, Part III.
Page 98 of 361
Change Description and Impact to
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300.4 Protection Against Physical
Damage. Where subject to physical
damage, conductors shall be
protected.
2008 NEC
Grounding conductors installed in
metal enclosures shall comply with
250.64(E).
Article 300
300.4 Protection Against Physical
Damage. Where subject to physical
damage, conductors shall be
protected.
(E) Cables and Raceways Installed
Under Roof Decking. A cable- or
raceway-type wiring method, installed
in exposed or concealed locations
under metal-corrugated sheet roof
decking, shall be installed and
supported so the nearest outside
surface of the cable or raceway is not
less than 38 mm (11⁄2 in.) from the
nearest surface of the roof decking.
Exception: Rigid metal conduit and
intermediate metal conduit shall not be
required to comply with 300.4(E).
(G) Insulated Fittings. Where raceways
contain 4 AWG or larger insulated
circuit conductors and these
conductors enter a cabinet, box,
enclosure, or raceway, the conductors
shall be protected by a substantial
fitting providing a smoothly rounded
Page 99 of 361
Change Description and Impact to
Worker Safety
Added new section E to address a
growing problem with roof decking
replacement or installation where the
roof decking screws penetrate
electrical metallic tubing and some
conduits or cables installed in the rafter
cavity. Some of these screws are over
6 inches long and require significant
torque to install.
As Safe or Safer.
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(F) Insulated Fittings. Where raceways
containing ungrounded conductors 4
AWG or larger enter a cabinet, box
enclosure, or raceway, the conductors
shall be protected by a substantial
fitting providing a smoothly rounded
insulating surface, unless the
conductors are separated from the
fitting or raceway by substantial
insulating material that is securely
fastened in place.
300.5 Underground Installations.
(B) Listing. Cables and insulated
conductors installed in enclosures or
raceways in underground installations
shall be listed for use in wet locations.
2008 NEC
insulating surface, unless the
conductors are separated from the
fitting or raceway by substantial
insulating material that is securely
fastened in place.
Change Description and Impact to
Worker Safety
Modified to clarify that it is the circuit
conductors that determine the need for
the substantial fitting, not just
ungrounded conductors.
As Safe or Safer.
300.5 Underground Installations.
300.5 Underground Installations.
(B) Wet Locations. The interior of
enclosures or raceways installed
underground shall be considered to be
a wet location. Insulated conductors
and cables installed in these
enclosures or raceways in
underground installations shall be
listed for use in wet locations and shall
comply with 310.8(C). Any connections
or splices in an underground
installation shall be approved for wet
locations.
300.5 Underground Installations.
(D) Protection from Damage. Directburied conductors and cables shall be
protected from damage in accordance
(D) Protection from Damage. Directburied conductors and cables shall be
protected from damage in accordance
Page 100 of 361
Finally, the declaration that the interior
of underground conduits are indeed a
wet location. It is well known that these
areas are wet, but now the declaration
helps reinforce the need for everything
to be listed for wet locations.
As Safe or Safer.
Clarified the intent of the original
requirement.
As Safe or Safer.
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Change Description and Impact to
Worker Safety
with 300.5(D)(1) through (D)(4).
with 300.5(D)(1) through (D)(4).
(1) Emerging from Grade. Direct-buried
conductors and enclosures emerging
from grade shall be protected by
enclosures or raceways extending from
the minimum cover distance below
grade required by 300.5(A) to a point
at least 2.5 m (8 ft) above finished
grade. In no case shall the protection
be required to exceed 450 mm (18 in.)
below finished grade.
(1) Emerging from Grade. Direct-buried
conductors and cables emerging from
grade and specified in columns 1 and
4 of Table 300.5 shall be protected by
enclosures or raceways extending from
the minimum cover distance below
grade required by 300.5(A) to a point
at least 2.5 m (8 ft) above finished
grade. In no case shall the protection
be required to exceed 450 mm (18 in.)
below finished grade.
300.6 Protection Against Corrosion
Changed “non-ferrous” to “aluminum”
and Deterioration.
to specifically address the attack on
aluminum by concrete materials and
(B) Aluminum Metal Equipment.
other underground chemicals versus
Aluminum raceways, cable trays,
the less catastrophic on other metals
cablebus, auxiliary gutters, cable
not containing iron.
armor, boxes, cable sheathing,
cabinets, elbows, couplings, nipples,
As Safe or Safer.
fittings, supports, and support
hardware embedded or encased in
concrete or in direct contact with the
earth shall be provided with
supplementary corrosion protection.
300.9 Raceways in Wet Locations
Finally, the declaration that the interior
Above Grade. Where raceways are
of conduits in wet locations are indeed
installed in wet locations above grade, themselves a wet location. It is well
the interior of these raceways shall be
known that these areas are wet, but
considered to be a wet location.
now the declaration in this new section
300.6 Protection Against Corrosion
and Deterioration.
(B) Non-Ferrous Metal Equipment.
Non-ferrous raceways, cable trays,
cablebus, auxiliary gutters, cable
armor, boxes, cable sheathing,
cabinets, elbows, couplings, nipples,
fittings, supports, and support
hardware embedded or encased in
concrete or in direct contact with the
earth shall be provided with
supplementary corrosion protection.
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Insulated conductors and cables
installed in raceways in wet locations
above grade shall comply with
310.8(C).
Change Description and Impact to
Worker Safety
300.9 helps reinforce the need for
everything to be listed for wet
locations.
As Safe or Safer.
300.11 Securing and Supporting.
300.11 Securing and Supporting.
Added “and shall be permitted to be
attached to the assembly” to indicate
(A) Secured in Place.
(A) Secured in Place.
that the support means could be
attached to the ceiling system, but not
(2) Non–Fire-Rated Assemblies. Wiring (2) Non–Fire-Rated Assemblies. Wiring individual conductors.
located within the cavity of a non–firelocated within the cavity of a non–firerated floor–ceiling or roof–ceiling
rated floor–ceiling or roof–ceiling
As Safe or Safer.
assembly shall not be secured to, or
assembly shall not be secured to, or
supported by, the ceiling assembly,
supported by, the ceiling assembly,
including the ceiling support wires. An
including the ceiling support wires. An
independent means of secure support
independent means of secure support
shall be provided.
shall be provided and shall be
permitted to be attached to the
assembly.
300.12 Mechanical Continuity —
300.12 Mechanical Continuity —
New Exception No. 2 added to address
Raceways and Cables. Metal or
Raceways and Cables. Metal or
the unnecessary limitations placed on
nonmetallic raceways, cable armors,
nonmetallic raceways, cable armors,
installations including the types of
and cable sheaths shall be continuous and cable sheaths shall be continuous equipment that incorporate open areas
between cabinets, boxes, fittings, or
between cabinets, boxes, fittings, or
for cable installation.
other enclosures or outlets.
other enclosures or outlets.
As Safe or Safer.
Exception No. 2: Raceways and cables
installed into the bottom of open
bottom equipment, such as
switchboards, motor control centers,
and floor or pad-mounted transformers,
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300.16 Raceway or Cable to Open or
Concealed Wiring.
(A) Box or Fitting. A box or terminal
fitting having a separately bushed hole
for each conductor shall be used
wherever a change is made from
conduit, electrical metallic tubing,
electrical nonmetallic tubing,
nonmetallic-sheathed cable, Type AC
cable, Type MC cable, or mineralinsulated, metal-sheathed cable and
surface raceway wiring to open wiring
or to concealed knob-and-tube wiring.
A fitting used for this purpose shall
contain no taps or splices and shall not
be used at luminaire (fixture) outlets.
300.19 Supporting Conductors in
Vertical Raceways.
2008 NEC
shall not be required to be
mechanically secured to the
equipment.
300.16 Raceway or Cable to Open or
Concealed Wiring.
Change Description and Impact to
Worker Safety
Adds conduit bodies to the types of
protection allowed for conductor
transitions and provides specific
requirements by reference.
(A) Box, Conduit Body, or Fitting. A
box, conduit body, or terminal fitting
having a separately bushed hole for
As Safe or Safer.
each conductor shall be used wherever
a change is made from conduit,
electrical metallic tubing, electrical
nonmetallic tubing, nonmetallicsheathed cable, Type AC cable, Type
MC cable, or mineral-insulated, metalsheathed cable and surface raceway
wiring to open wiring or to concealed
knob-and-tube wiring. A fitting used for
this purpose shall contain no taps or
splices and shall not be used at
luminaire outlets. A conduit body used
for this purpose shall contain no taps
or splices, unless it complies with
314.16(C)(2).
300.19 Supporting Conductors in
Inserted new (B) to address the
Vertical Raceways.
support methods allowed for fire-rated
cables and conductors not specifically
(B) Fire-Rated Cables and Conductors. addressed previously.
Support methods and spacing intervals
for fire-rated cables and conductors
As Safe or Safer.
shall comply with any restrictions
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provided in the listing of the electrical
circuit protective system used and in
no case shall exceed the values in
Table 300.19(A).
300.20 Induced Currents in Metal
300.20 Induced Currents in Ferrous
Enclosures or Metal Raceways.
Metal Enclosures or Ferrous Metal
(A) Conductors Grouped Together.
Raceways.
Where conductors carrying alternating (A) Conductors Grouped Together.
current are installed in metal
Where conductors carrying alternating
enclosures or metal raceways, they
current are installed in ferrous metal
shall be arranged so as to avoid
enclosures or ferrous metal raceways,
heating the surrounding metal by
they shall be arranged so as to avoid
induction. To accomplish this, all phase heating the surrounding ferrous metal
conductors and, where used, the
by induction. To accomplish this, all
grounded conductor and all equipment phase conductors and, where used,
grounding conductors shall be grouped the grounded conductor and all
together.
equipment grounding conductors shall
be grouped together.
300.22 Wiring in Ducts, Plenums, and
300.22 Wiring in Ducts, Plenums, and
Other Air-Handling Spaces.
Other Air-Handling Spaces.
(C) Other Space Used for
Environmental Air.
(C) Other Space Used for
Environmental Air.
(1) Wiring Methods. The wiring
methods for such other space shall be
limited to totally enclosed,
nonventilated, insulated busway having
no provisions for plug-in connections,
Type MI cable, Type MC cable without
an overall nonmetallic covering, Type
(1) Wiring Methods. The wiring
methods for such other space shall be
limited to totally enclosed,
nonventilated, insulated busway having
no provisions for plug-in connections,
Type MI cable, Type MC cable without
an overall nonmetallic covering, Type
Page 104 of 361
Change Description and Impact to
Worker Safety
Added “ferrous” since that is the type
of material that is susceptible to
inductive heating effects. This change
allows non-ferrous metallic raceways
to contain some but not all phase
conductors of a circuit, but should only
be employed where necessary due to
physical constraints.
As Safe or Safer.
Allows for the installation of raceways
in the metal wiring methods allowed in
air handling spaces.
As Safe or Safer.
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AC cable, or other factory assembled
multiconductor control or power cable
that is specifically listed for the use, or
listed prefabricated cable assemblies
of metallic manufactured wiring
systems without nonmetallic sheath.
Other types of cables, conductors,
and raceways shall be permitted to be
installed in electrical metallic tubing,
flexible metallic tubing, intermediate
metal conduit, rigid metal conduit
without an overall nonmetallic
covering, flexible metal conduit, or,
where accessible, surface metal
raceway or metal wireway with metal
covers or solid bottom metal cable tray
with solid metal covers.
300.40 Insulation Shielding. Metallic
300.40 Insulation Shielding. Metallic
and semiconducting insulation
and semiconducting insulation
shielding components of shielded
shielding components of shielded
cables shall be removed for a distance cables shall be removed for a distance
dependent on the circuit voltage and
dependent on the circuit voltage and
insulation. Stress reduction means
insulation. Stress reduction means
shall be provided at all terminations of
shall be provided at all terminations of
factory-applied shielding.
factory-applied shielding.
Metallic shielding components such as Metallic shielding components such as
tapes, wires, or braids, or combinations tapes, wires, or braids, or combinations
thereof, and their associated
thereof, shall be connected to a
conducting or semiconducting
grounding conductor, grounding
components shall be grounded.
busbar, or a grounding electrode.
300.50 Underground Installations.
300.50 Underground Installations.
Change Description and Impact to
Worker Safety
AC cable, or other factory assembled
multiconductor control or power cable
that is specifically listed for the use, or
listed prefabricated cable assemblies
of metallic manufactured wiring
systems without nonmetallic sheath.
Other types of cables and conductors
shall be installed in electrical metallic
tubing, flexible metallic tubing,
intermediate metal conduit, rigid metal
conduit without an overall nonmetallic
covering, flexible metal conduit, or,
where accessible, surface metal
raceway or metal wireway with metal
covers or solid bottom metal cable tray
with solid metal covers.
Page 105 of 361
Continuing with the emphasis on
“connected to a grounding
conductor….” versus just “grounded”
provides assurance of a connection to
ground. Eliminates the ambiguous
reference to “associated” components.
Actually improves worker safety by
assuring a continuous ground path.
Changed wording to eliminate
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(B) Protection from Damage.
Conductors emerging from the ground
shall be enclosed in listed raceways.
Raceways installed on poles shall be
of rigid metal conduit, intermediate
metal conduit, PVC Schedule 80, or
equivalent, extending from the
minimum cover depth specified in
Table 300.50 to a point 2.5 m (8 ft)
above finished grade. Conductors
entering a building shall be protected
by an approved enclosure or raceway
from the minimum cover depth to the
point of entrance. Where direct-buried
conductors, raceways, or cables are
subject to movement by settlement or
frost, they shall be installed to prevent
damage to the enclosed conductors or
to the equipment connected to the
raceways. Metallic enclosures shall be
grounded.
Table 300.50 Minimum Cover
Requirements
(B) Protection from Damage.
Conductors emerging from the ground
shall be enclosed in listed raceways.
Raceways installed on poles shall be
of rigid metal conduit, intermediate
metal conduit, Schedule 80 PVC
conduit, or equivalent, extending from
the minimum cover depth specified in
Table 300.50 to a point 2.5 m (8 ft)
above finished grade. Conductors
entering a building shall be protected
by an approved enclosure or raceway
from the minimum cover depth to the
point of entrance. Where direct-buried
conductors, raceways, or cables are
subject to movement by settlement or
frost, they shall be installed to prevent
damage to the enclosed conductors or
to the equipment connected to the
raceways. Metallic enclosures shall be
grounded.
Table 300.50 Minimum Cover
Requirements
General Notes:
General Notes:
3. In industrial establishments, where
conditions of maintenance and
supervision ensure that qualified
persons will service the installation, the
Page 106 of 361
Change Description and Impact to
Worker Safety
confusion and to specifically identify
“Schedule 80 PVC conduit” versus
“PVC Schedule 80” so listed conduit
would be used.
As Safe or Safer.
Added new Note 3 to allow reduction
of the backfill requirement by six
inches for each 2” of concrete cover.
Applicable to 600V and above
underground installations other than in
rigid metal conduit and intermediate
metal conduit in industrial
establishments.
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Table 300.50 Minimum Cover
Requirements
minimum cover requirements, for other
than rigid metal conduit and
intermediate metal conduit, shall be
permitted to be reduced 150 mm (6 in.)
for each 50 mm (2 in.) of concrete or
equivalent placed entirely within the
trench over the underground
installation.
Table 300.50 Minimum Cover
Requirements
Specific Footnotes:
Specific Footnotes:
Change Description and Impact to
Worker Safety
As Safe or Safer.
Added new footnote d to require a
marker tape to be installed over
unprotected direct buried cables which
will provide some measure of contact
avoidance by excavators.
d
310.4 Conductors in Parallel.
Underground direct-buried cables
that are not encased or protected by
concrete and are buried 750 mm (30
in.) or more below grade shall have
their location identified by a warning
ribbon that is placed in the trench at
least 300 mm (12 in.) above the
cables.
Article 310
310.4 Conductors in Parallel.
Aluminum, copper-clad aluminum, or
copper conductors of size 1/0 AWG
and larger, comprising each phase,
polarity, neutral, or grounded circuit
conductor, shall be permitted to be
connected in parallel (electrically joined
at both ends).
(A) General. Aluminum, copper-clad
aluminum, or copper conductors of
size 1/0 AWG and larger, comprising
each phase, polarity, neutral, or
grounded circuit conductor shall be
permitted to be connected in parallel
(electrically joined at both ends).
Page 107 of 361
Improves worker safety.
Deleted old Exception 1 and reference
to Article 620. Made provision for
higher frequency systems by
combining old Exceptions 2 and 3 into
new Exception 2. Old Exception 4
becomes Exception 2.
As Safe or Safer.
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Exception No. 1: As permitted in
620.12(A)(1).
Exception No. 2: Conductors in sizes
smaller than 1/0 AWG shall be
permitted to be run in parallel to
supply control power to indicating
instruments, contactors, relays,
solenoids, and similar control devices,
provided all of the following apply:
(a) They are contained within the
same raceway or cable.
(b) The ampacity of each individual
conductor is sufficient to carry the
entire load current shared by the
parallel conductors.
(c) The overcurrent protection is
such that the ampacity of each
individual conductor will not be
exceeded if one or more of the
parallel conductors become
inadvertently disconnected.
Exception No. 3: Conductors in sizes
smaller than 1/0 AWG shall be
permitted to be run in parallel for
frequencies of 360 Hz and higher
where conditions (a), (b), and (c) of
Exception No. 2 are met.
2008 NEC

Exception No. 1: Conductors in sizes
smaller than 1/0 AWG shall be
permitted to be run in parallel to supply
control power to indicating instruments,
contactors, relays, solenoids, and
similar control devices, or for
frequencies of 360 Hz and higher,
provided all of the following apply:
(a) They are contained within the
same raceway or cable.
(b) The ampacity of each individual
conductor is sufficient to carry the
entire load current shared by the
parallel conductors.
(c) The overcurrent protection is
such that the ampacity of each
individual conductor will not be
exceeded if one or more of the
parallel conductors become
inadvertently disconnected.
Exception No. 2: Under engineering
supervision, grounded neutral
conductors in sizes 2 AWG and larger
shall be permitted to be run in parallel
for existing installations.
Page 108 of 361
Change Description and Impact to
Worker Safety
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Exception No. 4: Under engineering
supervision, grounded neutral
conductors in sizes 2 AWG and larger
shall be permitted to be run in parallel
for existing installations.
310.4 Conductors in Parallel.
The paralleled conductors in each
phase, polarity, neutral, or grounded
circuit conductor shall comply with all
of the following:
(1) Be the same length
(2) Have the same conductor material
(3) Be the same size in circular mil
area
(4) Have the same insulation type
(5) Be terminated in the same manner
2008 NEC
310.4 Conductors in Parallel.
310.4 Conductors in Parallel.
(B) Conductor Characteristics. The
paralleled conductors in each phase,
polarity, neutral, grounded circuit
conductor, or equipment grounding
conductor shall comply with all of the
following:
(1) Be the same length
(2) Have the same conductor material
(3) Be the same size in circular mil
area
(4) Have the same insulation type
(5) Be terminated in the same manner
310.4 Conductors in Parallel.
Where run in separate raceways or
cables, the raceways or cables shall
have the same physical characteristics.
Where conductors are in separate
raceways or cables, the same number
of conductors shall be used in each
raceway or cable. Conductors of one
phase, polarity, neutral, or grounded
circuit conductor shall not be required
to have the same physical
(C) Separate Cables or Raceways.
Where run in separate cables or
raceways, the cables or raceways with
conductors shall have the same
number of conductors and shall have
the same electrical characteristics.
Conductors of one phase, polarity,
neutral, grounded circuit conductor, or
equipment grounding conductor shall
not be required to have the same
Page 109 of 361
Change Description and Impact to
Worker Safety
Reorganized sections to provide
headings and consolidate information
as well as include equipment
grounding conductors in the parallel
requirements.
As Safe or Safer.
Reorganized sections to provide
headings and consolidate information
as well as include equipment
grounding conductors in the parallel
requirements.
As Safe or Safer.
70 2008 851 Evaluation
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characteristics as those of another
phase, polarity, neutral, or grounded
circuit conductor to achieve balance.
2008 NEC
310.4 Conductors in Parallel.
physical characteristics as those of
another phase, polarity, neutral,
grounded circuit conductor, or
equipment grounding conductor to
achieve balance.

310.4 Conductors in Parallel.
Conductors installed in parallel shall
comply with the provisions of
310.15(B)(2)(a).
310.4 Conductors in Parallel.
(D) Ampacity Adjustment. Conductors
installed in parallel shall comply with
the provisions of 310.15(B)(2)(a).
310.4 Conductors in Parallel.
Where equipment grounding
conductors are used with conductors in
parallel, they shall comply with the
requirements of this section except that
they shall be sized in accordance with
250.122.
(E) Equipment Grounding Conductors.
Where parallel equipment grounding
conductors are used, they shall be
sized in accordance with 250.122.
Sectioned equipment grounding
conductors smaller than 1/0 AWG shall
be permitted in multiconductor cables
in accordance with 310.13, provided
the combined circular mil area in each
cable complies with 250.122.
310.6 Shielding. Solid dielectric
insulated conductors operated above
2000 volts in permanent installations
shall have ozone-resistant insulation
and shall be shielded. All metallic
insulation shields shall be connected to
a grounding electrode conductor,
grounding busbar, or a grounding
310.6 Shielding. Solid dielectric
insulated conductors operated above
2000 volts in permanent installations
shall have ozone-resistant insulation
and shall be shielded. All metallic
insulation shields shall be grounded
through an effective grounding path
meeting the requirements of
Page 110 of 361
Change Description and Impact to
Worker Safety
Deleted Fine Print Note.
Reorganized sections to provide
headings and consolidate information.
As Safe or Safer.
Reorganized sections to provide
headings and consolidate information
as well as include equipment
grounding conductors in the parallel
requirements.
As Safe or Safer.
Continuing effort to clarify the
connection to the grounding electrode
system versus the loose term
“grounded” for meeting the
requirements of the section. Exception
1 redirected the reference to the
appropriate table in the 2008 Code and
Exception No. 2 was added to provide
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250.4(A)(5) or 250.4(B)(4). Shielding
shall be for the purpose of confining
the voltage stresses to the insulation.
electrode. Shielding shall be for the
purpose of confining the voltage
stresses to the insulation.
Exception: Nonshielded insulated
conductors listed by a qualified testing
laboratory shall be permitted for use up
to 2400 volts under the following
conditions:
(a) Conductors shall have insulation
resistant to electric discharge and
surface tracking, or the insulated
conductor(s) shall be covered with a
material resistant to ozone, electric
discharge, and surface tracking.
(b) Where used in wet locations, the
insulated conductor(s) shall have an
overall nonmetallic jacket or a
continuous metallic sheath.
(c) Insulation and jacket thicknesses
shall be in accordance with Table
310.63.
Exception No. 1: Nonshielded
insulated conductors listed by a
qualified testing laboratory shall be
permitted for use up to 2400 volts
under the following conditions:
(a) Conductors shall have insulation
resistant to electric discharge and
surface tracking, or the insulated
conductor(s) shall be covered with a
material resistant to ozone, electric
discharge, and surface tracking.
(b) Where used in wet locations, the
insulated conductor(s) shall have an
overall nonmetallic jacket or a
continuous metallic sheath.
(c) Insulation and jacket thicknesses
shall be in accordance with Table
310.13(D).
Change Description and Impact to
Worker Safety
cross reference to section 310.7
Exception No. 2.
As Safe or Safer.
Exception No. 2: Where permitted in
310.7, Exception No. 2.
310.7 Direct Burial Conductors.
310.7 Direct-Burial Conductors.
Conductors used for direct burial
Conductors used for direct-burial
applications shall be of a type identified applications shall be of a type identified
for such use.
for such use.
Cables rated above 2000 volts shall be Cables rated above 2000 volts shall be
shielded.
shielded.
Page 111 of 361
Continuing effort to clarify the
connection to the grounding electrode
system versus the loose term
“grounded” for meeting the
requirements of the section. Exception
1 modified to reduce the allowable
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Exception: Nonshielded multiconductor
cables rated 2001– 5000 volts shall be
permitted if the cable has an overall
metallic sheath or armor.
Exception No. 1: Nonshielded
multiconductor cables rated 2001–
2400 volts shall be permitted if the
cable has an overall metallic sheath or
armor.
Change Description and Impact to
Worker Safety
voltage for cables without shields and
Exception No. 2 was added to allow
the special case for airport lighting
since it is a particularly different case
than other medium voltage systems.
As Safe or Safer.
The metallic shield, sheath, or armor
shall be grounded through an effective
grounding path meeting the
requirements of 250.4(A)(5) or (B)(4).
The metallic shield, sheath, or armor
shall be connected to a grounding
electrode conductor, grounding busbar,
or a grounding electrode.
310.8 Locations.
Exception No. 2: Airfield lighting cable
used in series circuits that are rated up
to 5000 volts and are powered by
regulators shall be permitted to be
nonshielded.
310.8 Locations.
(D) Locations Exposed to Direct
Sunlight. Insulated conductors or
cables used where exposed to direct
rays of the sun shall comply with one
of the following:
(1) Cables listed, or listed and marked,
as being sunlight resistant
(2) Conductors listed, or listed and
marked, as being sunlight resistant
(3) Covered with insulating material,
such as tape or sleeving, that is listed,
or listed and marked, as being sunlight
(D) Locations Exposed to Direct
Sunlight. Insulated conductors or
cables used where exposed to direct
rays of the sun shall comply with (D)(1)
or (D)(2):
(1) Conductors and cables shall be
listed, or listed and marked, as being
sunlight resistant
(2) Conductors and cables shall be
covered with insulating material, such
as tape or sleeving, that is listed, or
listed and marked, as being sunlight
Page 112 of 361
Consolidated subsections and made
the language specifically directive to
emphasize the intended action.
As Safe or Safer.
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resistant
310.13 Conductor Constructions and
Applications. Insulated conductors
shall comply with the applicable
provisions of one or more of the
following: Table 310.13, Table 310.61,
Table 310.62, Table 310.63, and Table
310.64.
These conductors shall be permitted
for use in any of the wiring methods
recognized in Chapter 3 and as
specified in their respective tables or
as permitted elsewhere in this Code.
Table 310.13, Table 310.61, Table
310.62, Table 310.63, and Table
310.64.
310.15 Ampacities for Conductors
Rated 0–2000 Volts.
2008 NEC
resistant
310.13 Conductor Constructions and
Applications. Insulated conductors
shall comply with the applicable
provisions of Table 310.13(A) through
Table 310.13(E).
These conductors shall be permitted
for use in any of the wiring methods
recognized in Chapter 3 and as
specified in their respective tables or
as permitted elsewhere in this Code.
Equipment grounding conductors shall
be permitted to be sectioned within a
listed multiconductor cable, provided
the combined circular mil area
complies with 250.122.
Table 310.13(A) through Table
310.13(E).
310.15 Ampacities for Conductors
Rated 0–2000 Volts.
Page 113 of 361
Change Description and Impact to
Worker Safety
Table renumbering necessitated the
reference changes. New paragraph
allows equipment grounding conductor
contained within a listed
multiconductor cable to be sectioned,
provided the equivalent conductor is
properly sized.
As Safe or Safer.
Table 310.13, Table 310.61, Table
310.62, Table 310.63, and Table
310.64 of the 2005 Code were
rearranged and modified slightly into
Table 310.13(A) through Table
310.13(E) for the 2008 Code mainly to
differentiate between voltage levels
covered in the tables.
As Safe or Safer.
Changed wording in (B)(2)(a) to clarify
the intent to allow for installations other
than just stacked or bundled. Added
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(B) Tables. Ampacities for conductors
rated 0 to 2000 volts shall be as
specified in the Allowable Ampacity
Table 310.16 through Table 310.19,
and Ampacity Table 310.20 and Table
310.21 as modified by (B)(1) through
(B)(6).
(B) Tables. Ampacities for conductors
rated 0 to 2000 volts shall be as
specified in the Allowable Ampacity
Table 310.16 through Table 310.19,
and Ampacity Table 310.20 and Table
310.21 as modified by (B)(1) through
(B)(6).
(1) General. For explanation of type
letters used in tables and for
recognized sizes of conductors for the
various conductor insulations, see
310.13. For installation requirements,
see 310.1 through 310.10 and the
various articles of this Code. For
flexible cords, see Table 400.4, Table
400.5(A), and Table 400.5(B).
(1) General. For explanation of type
letters used in tables and for
recognized sizes of conductors for the
various conductor insulations, see
Table 310.13(A) and Table 310.13(B).
For installation requirements, see
310.1 through 310.10 and the various
articles of this Code. For flexible cords,
see Table 400.4, Table 400.5(A), and
Table 400.5(B).
(2) Adjustment Factors.
(2) Adjustment Factors.
(a) More Than Three Current(a) More Than Three CurrentCarrying Conductors in a Raceway
Carrying Conductors in a Raceway
or Cable. Where the number of
or Cable. Where the number of
current-carrying conductors in a
current-carrying conductors in a
raceway or cable exceeds three, or
raceway or cable exceeds three, or
where single conductors or
where single conductors or
multiconductor cables are stacked
multiconductor cables are installed
or bundled longer than 600 mm (24
without maintaining spacing for a
in.) without maintaining spacing and
continuous length longer than 600
are not installed in raceways, the
mm (24 in.) and are not installed in
allowable ampacity of each
raceways, the allowable ampacity of
Page 114 of 361
Change Description and Impact to
Worker Safety
(B)(2)(c) to address the concern of
conductors installed outside on
rooftops exposed to direct sunlight and
the effect that it has on ampacity.
Reworded (B)(3) to clarify the intent to
have the temperature rating of the
covered or bare conductors compared
with the insulated conductors in the
installation. Inserted “conductor” in
(B)(4) to reinforce the proper use of the
term and address the fact that it is a
conductor, not some other entity that is
to be considered.
As Safe or Safer.
70 2008 851 Evaluation
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conductor shall be reduced as
shown in Table 310.15(B)(2)(a).
Each current-carrying conductor of
a paralleled set of conductors shall
be counted as a current carrying
conductor.
(b) More Than One Conduit, Tube,
or Raceway. Spacing between
conduits, tubing, or raceways shall
be maintained.
(3) Bare or Covered Conductors.
Where bare or covered conductors are
used with insulated conductors, their
allowable ampacities shall be limited to
those permitted for the adjacent
insulated conductors.
2008 NEC
each conductor shall be reduced as
shown in Table 310.15(B)(2)(a).
Each current-carrying conductor of a
paralleled set of conductors shall be
counted as a current-carrying
conductor.
(b) More Than One Conduit, Tube,
or Raceway. Spacing between
conduits, tubing, or raceways shall
be maintained.
(c) Conduits Exposed to Sunlight on
Rooftops. Where conductors or
cables are installed in conduits
exposed to direct sunlight on or
above rooftops, the adjustments
shown in Table 310.15(B)(2)(c) shall
be added to the outdoor
temperature to determine the
applicable ambient temperature for
application of the correction factors
in Table 310.16 and Table 310.18.
(3) Bare or Covered Conductors.
Where bare or covered conductors are
installed with insulated conductors, the
temperature rating of the bare or
covered conductor shall be equal to
the lowest temperature rating of the
insulated conductors for the purpose of
determining ampacity.
Page 115 of 361
Change Description and Impact to
Worker Safety
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Change Description and Impact to
Worker Safety
(4) Neutral Conductor.
(4) Neutral Conductor.
(a) A neutral conductor that carries
(a) A neutral conductor that carries
only the unbalanced current from
only the unbalanced current from
other conductors of the same circuit
other conductors of the same circuit
shall not be required to be counted
shall not be required to be counted
when applying the provisions of
when applying the provisions of
310.15(B)(2)(a).
310.15(B)(2)(a).
(b) In a 3-wire circuit consisting of
(b) In a 3-wire circuit consisting of
two phase wires and the neutral of
two phase conductors and the
a 4-wire, 3-phase, wye-connected
neutral conductor of a 4-wire, 3system, a common conductor
phase, wye connected system, a
carries approximately the same
common conductor carries
current as the line-to-neutral load
approximately the same current as
currents of the other conductors
the line-to-neutral load currents of
and shall be counted when applying
the other conductors and shall be
the provisions of 310.15(B)(2)(a).
counted when applying the
(c) On a 4-wire, 3-phase wye circuit
provisions of 310.15(B)(2)(a).
where the major portion of the load
(c) On a 4-wire, 3-phase wye circuit
consists of nonlinear loads,
where the major portion of the load
harmonic currents are present in
consists of nonlinear loads,
the neutral conductor; the neutral
harmonic currents are present in the
shall therefore be considered a
neutral conductor; the neutral
current-carrying conductor.
conductor shall therefore be
considered a current-carrying
conductor.
Article 312
I. Installation
I. Installation
312.2 Damp, Wet, or Hazardous
(Classified) Locations.
Page 116 of 361
Deleted reference to “Hazardous
(Classified) Locations” since by
definition these requirements are found
in Articles 500 through 517, regardless
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2008 NEC
Change Description and Impact to
Worker Safety
of wet or damp conditions.
(A) Damp and Wet Locations. In damp
or wet locations, surface-type
enclosures within the scope of this
article shall be placed or equipped so
as to prevent moisture or water from
entering and accumulating within the
cabinet or cutout box, and shall be
mounted so there is at least 6-mm (1⁄4in.) airspace between the enclosure
and the wall or other supporting
surface. Enclosures installed in wet
locations shall be weatherproof. For
enclosures in wet locations, raceways
or cables entering above the level of
uninsulated live parts shall use fittings
listed for wet locations.
312.2 Damp and Wet Locations. In
damp or wet locations, surface-type
As Safe or Safer.
enclosures within the scope of this
article shall be placed or equipped so
as to prevent moisture or water from
entering and accumulating within the
cabinet or cutout box, and shall be
mounted so there is at least 6-mm (1⁄4in.) airspace between the enclosure
and the wall or other supporting
surface. Enclosures installed in wet
locations shall be weatherproof. For
enclosures in wet locations, raceways
or cables entering above the level of
uninsulated live parts shall use fittings
listed for wet locations.
(B) Hazardous (Classified) Locations.
Installations in hazardous (classified)
locations shall conform to Articles 500
through 517.
312.4 Repairing Plaster and Drywall or
Plasterboard. Plaster, drywall, or
plasterboard surfaces that are broken
or incomplete shall be repaired so
there will be no gaps or open spaces
greater than 3 mm (1⁄8 in.) at the edge
of the cabinet or cutout box employing
a flush-type cover.

312.4 Repairing Noncombustible
Surfaces. Noncombustible surfaces
that are broken or incomplete shall be
repaired so there will be no gaps or
open spaces greater than 3 mm (1⁄8
in.) at the edge of the cabinet or cutout
box employing a flush-type cover.
Article 314
Page 117 of 361
Changed surface types to be more
inclusive of the many types of surfaces
available.
As Safe or Safer.
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2008 NEC
314.4 Metal Boxes. All metal boxes
shall be grounded in accordance with
the provisions of Article 250.
314.4 Metal Boxes. Metal boxes shall
be grounded and bonded in
accordance with Parts I, IV, V, VI, VII,
and X of Article 250 as applicable,
except as permitted in 250.112(I).
II. Installation
II. Installation
314.15 Damp, Wet, or Hazardous
(Classified) Locations.
314.15 Damp or Wet Locations. In
damp or wet locations, boxes, conduit
bodies, and fittings shall be placed or
(A) Damp or Wet Locations. In damp or equipped so as to prevent moisture
wet locations, boxes, conduit bodies,
from entering or accumulating within
and fittings shall be placed or equipped the box, conduit body, or fitting. Boxes,
so as to prevent moisture from entering conduit bodies, and fittings installed in
or accumulating within the box, conduit wet locations shall be listed for use in
body, or fitting. Boxes, conduit bodies, wet locations.
and fittings installed in wet locations
shall be listed for use in wet locations.
(B) Hazardous (Classified) Locations.
Installations in hazardous (classified)
locations shall conform to Articles
500 through 517.
314.16 Number of Conductors in
Outlet, Device, and Junction Boxes,
and Conduit Bodies. Boxes and
conduit bodies shall be of sufficient
size to provide free space for all
enclosed conductors. In no case shall
the volume of the box, as calculated in
Change Description and Impact to
Worker Safety
More specific direction provided to
eliminate confusion and misapplication
of the grounding and bonding
requirements.
As Safe or Safer.
Deleted reference to “Hazardous
(Classified) Locations” since by
definition these requirements are found
in Articles 500 through 517, regardless
of wet or damp conditions.
As Safe or Safer.

314.16 Number of Conductors in
Outlet, Device, and Junction Boxes,
and Conduit Bodies. Boxes and
conduit bodies shall be of sufficient
size to provide free space for all
enclosed conductors. In no case shall
the volume of the box, as calculated in
Page 118 of 361
Generators were added as an
exception since the same situation
exists for manufacturer supplied
generator connections as for
manufacturer supplied motor terminals.
As Safe or Safer.
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Change Description and Impact to
Worker Safety
314.16(A), be less than the fill
calculation as calculated in 314.16(B).
The minimum volume for conduit
bodies shall be as calculated in
314.16(C).
The provisions of this section shall not
apply to terminal housings supplied
with motors.
314.16 Number of Conductors in
Outlet, Device, and Junction Boxes,
and Conduit Bodies.
314.16(A), be less than the fill
calculation as calculated in 314.16(B).
The minimum volume for conduit
bodies shall be as calculated in
314.16(C).
The provisions of this section shall not
apply to terminal housings supplied
with motors or generators.
314.16 Number of Conductors in
Outlet, Device, and Junction Boxes,
and Conduit Bodies.
(B) Box Fill Calculations.
(B) Box Fill Calculations.
(1) Conductor Fill. Each conductor that
originates outside the box and
terminates or is spliced within the box
shall be counted once, and each
conductor that passes through the box
without splice or termination shall be
counted once. A looped, unbroken
conductor not less than twice the
minimum length required for free
conductors in 300.14 shall be counted
twice. The conductor fill shall be
calculated using Table 314.16(B). A
conductor, no part of which leaves the
box, shall not be counted.
314.16 Number of Conductors in
Outlet, Device, and Junction Boxes,
and Conduit Bodies.
(1) Conductor Fill. Each conductor that
originates outside the box and
terminates or is spliced within the box
shall be counted once, and each
conductor that passes through the box
without splice or termination shall be
counted once. Each loop or coil of
unbroken conductor not less than twice
the minimum length required for free
conductors in 300.14 shall be counted
twice. The conductor fill shall be
calculated using Table 314.16(B). A
conductor, no part of which leaves the
box, shall not be counted.
314.16 Number of Conductors in
Added double volume allowance
Outlet, Device, and Junction Boxes,
requirements for devices and
and Conduit Bodies.
equipment wider than a standard
Clarified wording to include “coil” as
well as “loop” to eliminate controversy.
As Safe or Safer.
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(B) Box Fill Calculations.
(B) Box Fill Calculations.
(4) Device or Equipment Fill. For each
yoke or strap containing one or more
devices or equipment, a double volume
allowance in accordance with Table
314.16(B) shall be made for each yoke
or strap based on the largest conductor
connected to a device(s) or equipment
supported by that yoke or strap.
(4) Device or Equipment Fill. For each
yoke or strap containing one or more
devices or equipment, a double volume
allowance in accordance with Table
314.16(B) shall be made for each yoke
or strap based on the largest conductor
connected to a device(s) or equipment
supported by that yoke or strap. A
device or utilization equipment wider
than a single 50 mm (2 in.) device box
as described in Table 314.16(A) shall
have double volume allowances
provided for each gang required for
mounting.
314.24 Minimum Depth of Boxes for
Outlets, Devices, and Utilization
Equipment. Outlet and device boxes
shall have sufficient depth to allow
equipment installed within them to be
mounted properly and with sufficient
clearance to prevent damage to
conductors within the box.
314.24 Depth of Outlet Boxes. No box
shall have an internal depth of less
than 12.7 mm (1⁄2 in.). Boxes intended
to enclose flush devices shall have an
internal depth of not less than 23.8 mm
(15⁄16 in.).
(A) Outlet Boxes Without Enclosed
Devices or Utilization Equipment. No
box shall have an internal depth of less
than 12.7 mm (1⁄2 in.).
Page 120 of 361
Change Description and Impact to
Worker Safety
single gang box to include them in the
criteria for box fill.
As Safe or Safer.
Significantly expanded this section to
address the problems encountered
when insufficient volume allowance
and box depth causes pinching of
wiring and forced installations of
devices or equipment.
Improves long term safety aspects of
electrical maintenance.
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(B) Outlet and Device Boxes with
Enclosed Devices. Boxes intended to
enclose flush devices shall have an
internal depth of not less than 23.8 mm
(15⁄16 in.).
(C) Utilization Equipment. Outlet and
device boxes that enclose utilization
equipment shall have a minimum
internal depth that accommodates the
rearward projection of the equipment
and the size of the conductors that
supply the equipment. The internal
depth shall include, where used, that of
any extension boxes, plaster rings, or
raised covers. The internal depth shall
comply with all applicable provisions of
(C)(1) through (C)(5).
(1) Large Equipment. Boxes that
enclose utilization equipment that
projects more than 48 mm (17⁄8 in.)
rearward from the mounting plane of
the box shall have a depth that is
not less than the depth of the
equipment plus 6 mm (1⁄4 in.).
(2) Conductors Larger Than 4 AWG.
Boxes that enclose utilization
equipment supplied by conductors
larger than 4 AWG shall be
Page 121 of 361
Change Description and Impact to
Worker Safety
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identified for their specific function.
(3) Conductors 8, 6, or 4 AWG.
Boxes that enclose utilization
equipment supplied by 8, 6, or 4
AWG conductors shall have an
internal depth that is not less than
52.4 mm (21⁄16 in.).
(4) Conductors 12 or 10 AWG.
Boxes that enclose utilization
equipment supplied by 12 or 10
AWG conductors shall have an
internal depth that is not less than
30.2 mm (13⁄16 in.). Where the
equipment projects rearward from
the mounting plane of the box by
more than 25 mm (1 in.), the box
shall have a depth not less than that
of the equipment plus 6 mm (1⁄4 in.).
(5) Conductors 14 AWG and
Smaller. Boxes that enclose
equipment supplied by 14 AWG or
smaller conductors shall have a
depth that is not less than 23.8 mm
(15⁄16 in.).
Exception to (C)(1) through (C)(5):
Utilization equipment that is listed to be
installed with specified boxes shall be
Page 122 of 361
Change Description and Impact to
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314.27 Outlet Boxes.
permitted.
314.27 Outlet Boxes.
(A) Boxes at Luminaire Outlets. Boxes
used at luminaire or lampholder outlets
in a ceiling shall be designed for the
purpose and shall be required to
support a luminaire weighing a
minimum of 23 kg (50 lb). Boxes used
at luminaire or lampholder outlets in a
wall shall be designed for the purpose
and shall be marked to indicate the
maximum weight of the luminaire that
is permitted to be supported by the box
in the wall, if other than 23 kg (50 lb).
At every outlet used exclusively for
lighting, the box shall be designed or
installed so that a luminaire may be
attached.
314.27 Outlet Boxes.
(B) Maximum Luminaire (Fixture)
Weight. Outlet boxes or fittings
installed as required by 314.23 shall be
permitted to support luminaires
(lighting fixtures) weighing 23 kg
(50 lb) or less. A luminaire (lighting
fixture) that weighs more than 23 kg
(50 lb) shall be supported
independently of the outlet box unless
the outlet box is listed for the weight to
be supported.
(B) Maximum Luminaire Weight. Outlet
boxes or fittings designed for the
support of luminaires and installed as
required by 314.23 shall be permitted
to support a luminaire weighing 23 kg
(50 lb) or less. A luminaire that weighs
more than 23 kg (50 lb) shall be
supported independently of the outlet
box unless the outlet box is listed and
marked for the maximum weight to be
supported.
314.27 Outlet Boxes.
(A) Boxes at Luminaire (Lighting
Fixture) Outlets. Boxes used at
luminaire (lighting fixture) or
lampholder outlets shall be designed
for the purpose. At every outlet used
exclusively for lighting, the box shall be
designed or installed so that a
luminaire (lighting fixture) may be
attached.
Page 123 of 361
Change Description and Impact to
Worker Safety
Clarified intent that the original section
addressed ceiling lighting and the
requirements for wall mounted lighting
were added. Language changes to
incorporate the term “luminaire”
referring to the “complete lighting unit
consisting of a light source such as a
lamp or lamps, together with the parts
designed to position the light source
and connect it to the power supply.”
As Safe or Safer.
Modified to address the requirement
that the box has to be designed, listed
and marked to carry the weight of
luminaires. Language changes to
incorporate the term “luminaire”
referring to the “complete lighting unit
consisting of a light source such as a
lamp or lamps, together with the parts
designed to position the light source
and connect it to the power supply.”
As Safe or Safer.
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314.27 Outlet Boxes.
2008 NEC
314.27 Outlet Boxes.
(E) Utilization Equipment. Boxes used
for the support of utilization equipment
other than ceiling-suspended (paddle)
fans shall meet the requirements of
314.27(A) and (B) for the support of a
luminaire that is the same size and
weight.
Change Description and Impact to
Worker Safety
New section added to specifically
address utilization equipment
supported by outlet boxes and that the
same requirements apply as for
luminaires. The exception for less than
3 kg allows mounting of lighter
equipment without the strict
requirements as in 314.27(A) or (B).
As Safe or Safer.
314.28 Pull and Junction Boxes and
Conduit Bodies.
(A) Minimum Size. For raceways
containing conductors of 4 AWG or
larger, and for cables containing
conductors of 4 AWG or larger, the
minimum dimensions of pull or junction
boxes installed in a raceway or cable
run shall comply with (A)(1) through
(A)(3).
314.30 Handhole Enclosures.
Exception: Utilization equipment
weighing not more than 3 kg (6 lb)
shall be permitted to be supported on
other boxes or plaster rings that are
secured to other boxes, provided the
equipment or its supporting yoke is
secured to the box with no fewer than
two No. 6 or larger screws.
314.28 Pull and Junction Boxes and
Conduit Bodies.
Clarification that the requirement only
applies to conductors required to be
insulated.
(A) Minimum Size. For raceways
containing conductors of 4 AWG or
As Safe or Safer.
larger that are required to be insulated,
and for cables containing conductors of
4 AWG or larger, the minimum
dimensions of pull or junction boxes
installed in a raceway or cable run
shall comply with (A)(1) through
(A)(3)….
314.30 Handhole Enclosures.
Clarified original intent and added the
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Handhole enclosures shall be
designed and installed to withstand all
loads likely to be imposed.
Handhole enclosures shall be
designed and installed to withstand all
loads likely to be imposed on them.
They shall be identified for use in
underground systems.
314.30 Handhole Enclosures.
314.30 Handhole Enclosures.
(C) Handhole Enclosures Without
Bottoms. Where handhole enclosures
without bottoms are installed, all
enclosed conductors and any splices
or terminations, if present, shall be
listed as suitable for wet locations.
314.30 Handhole Enclosures.
(C) Enclosed Wiring. All enclosed
conductors and any splices or
terminations, if present, shall be listed
as suitable for wet locations.
(D) Covers. Handhole enclosure
covers shall have an identifying mark
or logo that prominently identifies the
function of the enclosure, such as
“electric.” Handhole enclosure covers
shall require the use of tools to open,
or they shall weigh over 45 kg (100 lb).
Metal covers and other exposed
conductive surfaces shall be bonded in
accordance with 250.96(A).
(D) Covers. Handhole enclosure
covers shall have an identifying mark
or logo that prominently identifies the
function of the enclosure, such as
“electric.” Handhole enclosure covers
shall require the use of tools to open,
or they shall weigh over 45 kg (100 lb).
Metal covers and other exposed
conductive surfaces shall be bonded in
accordance with 250.92(A) if the
conductors in the handhole are service
conductors, or in accordance with
250.96(A) if the conductors in the
handhole are feeder or branch-circuit
conductors.
Article 320
Change Description and Impact to
Worker Safety
requirement that the enclosures need
to be identified for underground use.
As Safe or Safer.
Modified to eliminate the caveat that
the handhole enclosures had to have
no bottom for the requirements of the
section to apply. It now applies to all
enclosed wiring in handholes.
As Safe or Safer.
314.30 Handhole Enclosures.
Page 125 of 361
Modified to redirect the user to the
proper section for services and to
differentiate them from feeders and
branch circuits.
As Safe or Safer.
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II. Installation
320.10 Uses Permitted. Type AC cable
shall be permitted as follows:
(1) In both exposed and concealed
work
(2) In cable trays
(3) In dry locations
(4) Embedded in plaster finish on
brick or other masonry, except in
damp or wet locations
(5) To be run or fished in the air
voids of masonry block or tile walls
where such walls are not exposed
or subject to excessive moisture or
dampness
II. Installation
320.10 Uses Permitted. Type AC cable
shall be permitted as follows:
(1) For feeders and branch circuits
in both exposed and concealed
work
(2) In cable trays
(3) In dry locations
(4) Embedded in plaster finish on
brick or other masonry, except in
damp or wet locations
(5) To be run or fished in the air
voids of masonry block or tile walls
where such walls are not exposed
or subject to excessive moisture or
dampness
320.108 Equipment Grounding. Type
320.108 Equipment Grounding
AC cable shall provide an adequate
Conductor. Type AC cable shall
path for equipment grounding as
provide an adequate path for fault
required by 250.4(A)(5) or 250.4(B)(4). current as required by 250.4(A)(5) or
(B)(4) to act as an equipment
grounding conductor.
Article 328
II. Installation
II. Installation
328.10 Uses Permitted. Type MV cable 328.10 Uses Permitted. Type MV cable
shall be permitted for use on power
shall be permitted for use on power
systems rated up to 35,000 volts
systems rated up to 35,000 volts
nominal as follows:
nominal as follows:
(1) In wet or dry locations
(1) In wet or dry locations
(2) In raceways
(2) In raceways
(3) In cable trays as specified in
(3) In cable trays, where identified for
Page 126 of 361
Change Description and Impact to
Worker Safety
Modified to restrict the use to feeders
and branch circuits and not services.
As Safe or Safer.
Emphasis on “conductor” to clarify that
it is the conduction of fault current that
must be adequate, not just a ground
connection.
As Safe or Safer.
Modified to stress the identification for
use of MV cable and to allow it to be
used if “identified as MV or MC.”
Added exposed runs per 300.37 as
another permitted use.
As Safe or Safer.
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392.3(B)(2)
2008 NEC
Change Description and Impact to
Worker Safety
the use, in accordance with 392.3,
392.6(F), 392.8, and 392.12.
Exception: Type MV cable that has an
overall metallic sheath or armor, also
complies with the requirements for
Type MC cable, and is identified as
“MV or MC” shall be permitted to be
installed in cable trays in accordance
with 392.3(B)(2).
(4) Direct buried in accordance with
300.50
(5) In messenger-supported wiring
328.12 Uses Not Permitted. Unless
identified for the use, Type MV cable
shall not be used as follows:
(1) Where exposed to direct sunlight
(2) In cable trays, unless specified in
392.3(B)(2)
(4) Direct buried in accordance with
300.50
(5) In messenger-supported wiring in
accordance with Part II of Article 396
(6) As exposed runs in accordance
with 300.37
Exception: Type MV cable that has an
overall metallic sheath or armor, also
complies with the requirements for
Type MC cable, and is identified as
“MV or MC” shall be permitted to be
installed as exposed runs of metal-clad
cable in accordance with 300.37.
328.12 Uses Not Permitted. Type MV
cable shall not be used where exposed
to direct sunlight, unless identified for
the use.
Items (2) and (3) changed language
and moved to Uses Permitted leaving
only direct sunlight exposure as a use
not permitted.
As Safe or Safer.
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Change Description and Impact to
Worker Safety
(3) Direct buried, unless in accordance
with 300.50
Article 330
II. Installation
330.10 Uses Permitted.
II. Installation
330.10 Uses Permitted.
Added “corrosion-resistant jacket”
requirement for the metal sheath Type
MC cable in wet locations.
(A) General Uses. Type MC cable shall (A) General Uses. Type MC cable shall
be permitted as follows:
be permitted as follows:
As Safe or Safer.
(11) In wet locations where any of the
following conditions are met:
a. The metallic covering is impervious
to moisture.
b. A lead sheath or moistureimpervious jacket is provided under the
metal covering.
c. The insulated conductors under the
metallic covering are listed for use in
wet locations.
330.12 Uses Not Permitted. Type MC
cable shall not be used where exposed
to the following destructive corrosive
conditions, unless the metallic sheath
is suitable for the conditions or is
protected by material suitable for the
conditions:
(1) Where subject to physical damage
(2) Direct burial in the earth
(3) In concrete
(11) In wet locations where any of the
following conditions are met:
a. The metallic covering is impervious
to moisture.
b. A lead sheath or moistureimpervious jacket is provided under the
metal covering.
c. The insulated conductors under the
metallic covering are listed for use in
wet locations and a corrosion-resistant
jacket is provided over the metallic
sheath.
330.12 Uses Not Permitted. Type MC
Separated the “subject to physical
cable shall not be used under either of damage” clause from the allowance
the following conditions:
provided by “unless the metallic sheath
or armor is resistant to the conditions
(1) Where subject to physical damage
or is protected by material resistant to
the conditions” to indicate that there is
(2) Where exposed to any of the
no remedy by the use of a sheath or
destructive corrosive conditions in (a)
armor.
or (b), unless the metallic sheath or
armor is resistant to the conditions or is As Safe or Safer.
Page 128 of 361
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(4) Where subject to cinder fills, strong
chlorides, caustic alkalis, or vapors of
chlorine or of hydrochloric acids
III. Construction Specifications
330.104 Conductors. The conductors
shall be of copper, aluminum, or
copper-clad aluminum, solid or
stranded. The minimum conductor size
shall be 18 AWG copper and 12 AWG
aluminum or copper-clad aluminum.
2008 NEC
protected by material resistant to the
conditions:
a. Direct buried in the earth or
embedded in concrete unless
identified for direct burial
b. Exposed to cinder fills, strong
chlorides, caustic alkalis, or vapors
of chlorine or of hydrochloric acids
III. Construction Specifications
III. Construction Specifications
330.104 Conductors. Conductors shall
be of copper, aluminum, copper-clad
aluminum, nickel or nickel-coated
copper, solid or stranded. The
minimum conductor size shall be 18
AWG copper, nickel or nickel-coated
copper, and 12 AWG aluminum or
copper-clad aluminum.
330.108 Equipment Grounding
Conductor. Where Type MC cable is
used to provide an equipment
grounding conductor, it shall comply
with 250.118(10) and 250.122.
Article 332
III. Construction Specifications
332.108 Equipment Grounding. Where
the outer sheath is made of copper, it
shall provide an adequate path for
equipment grounding purposes. Where
made of steel, an equipment grounding
332.108 Equipment Grounding
Conductor. Where the outer sheath is
made of copper, it shall provide an
adequate path to serve as an
equipment grounding conductor.
330.108 Equipment Grounding. Where
Type MC cable is used for equipment
grounding, it shall comply with
250.118(10) and 250.122.
Page 129 of 361
Change Description and Impact to
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Inserted “nickel, or nickel-coated
copper” to allow for newer
manufacturing techniques. Table
references changed to coordinate with
changes in the tables.
As Safe or Safer.
Emphasis on conductor to make it
clear that there is a specific function it
performs.
As Safe or Safer.
Continued emphasis on conductor to
make it clear that there is a specific
function it performs.
As Safe or Safer.
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conductor shall be provided.
ARTICLE 334
Nonmetallic-Sheathed Cable:
Types NM, NMC, and NMS
2008 NEC
Where the outer sheath is made of
steel, a separate equipment grounding
conductor shall be provided.
Article 334
ARTICLE 334
Nonmetallic-Sheathed Cable:
Types NM, NMC, and NMS
Change Description and Impact to
Worker Safety
Added exception to allow cables in
conduit rated for the location type.
As Safe or Safer.
334.12 Uses Not Permitted.
(A) Types NM, NMC, and NMS. Types
NM, NMC, and NMS cables shall not
be permitted as follows:
(1) In any dwelling or structure not
specifically permitted in 334.10(1), (2),
and (3)
334.12 Uses Not Permitted.
(B) Types NM and NMS. Types NM
and NMS cables shall not be used
under the following conditions or in the
following locations:
(1) Where exposed to corrosive fumes
or vapors
(2) Where embedded in masonry,
concrete, adobe, fill, or plaster
(3) In a shallow chase in masonry,
concrete, or adobe and covered with
334.12 Uses Not Permitted.
(A) Types NM, NMC, and NMS. Types
NM, NMC, and NMS cables shall not
be permitted as follows:
(1) In any dwelling or structure not
specifically permitted in 334.10(1), (2),
and (3)
Exception: Type NM, NMC, and NMS
cable shall be permitted in Type I and
II construction when installed within
raceways permitted to be installed in
Type I and II construction.
334.12 Uses Not Permitted.
(B) Types NM and NMS. Types NM
and NMS cables shall not be used
under the following conditions or in the
following locations:
(1) Where exposed to corrosive fumes
or vapors
(2) Where embedded in masonry,
concrete, adobe, fill, or plaster
(3) In a shallow chase in masonry,
concrete, or adobe and covered with
Page 130 of 361
Points to specific definition for wet or
damp locations to reduce the
confusion and misinterpretation.
As Safe or Safer.
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plaster, adobe, or similar finish
(4) Where exposed or subject to
excessive moisture or dampness
334.15 Exposed Work.
plaster, adobe, or similar finish
(4) In wet or damp locations
(B) Protection from Physical Damage.
Cable shall be protected from physical
damage where necessary by rigid
metal conduit, intermediate metal
conduit, electrical metallic tubing,
Schedule 80 PVC rigid nonmetallic
conduit, or other approved means.
Where passing through a floor, the
cable shall be enclosed in rigid metal
conduit, intermediate metal conduit,
electrical metallic tubing, Schedule 80
PVC rigid nonmetallic conduit, or other
approved means extending at least
150 mm (6 in.) above the floor.
Where Type NMC cable is installed in
shallow chases in masonry, concrete,
or adobe, the cable shall be protected
against nails or screws by a steel plate
at least 1.59 mm (1⁄16 in.) thick and
covered with plaster, adobe, or similar
finish.
334.15 Exposed Work.
(B) Protection from Physical Damage.
Cable shall be protected from physical
damage where necessary by rigid
metal conduit, intermediate metal
conduit, electrical metallic tubing,
Schedule 80 PVC conduit, or other
approved means. Where passing
through a floor, the cable shall be
enclosed in rigid metal conduit,
intermediate metal conduit, electrical
metallic tubing, Schedule 80 PVC
conduit, or other approved means
extending at least 150 mm (6 in.)
above the floor.
Type NMC cable installed in shallow
chases or grooves in masonry,
concrete, or adobe, shall be protected
in accordance with the requirements in
300.4(E) and covered with plaster,
adobe, or similar finish.
(C) In Unfinished Basements. Where
cable is run at angles with joists in
unfinished basements, it shall be
(C) In Unfinished Basements and
Crawl Spaces. Where cable is run at
angles with joists in unfinished
334.15 Exposed Work.
334.15 Exposed Work.
Page 131 of 361
Change Description and Impact to
Worker Safety
Removed “rigid nonmetallic” from the
PVC conduit as it was redundant. Now
refers to Article 300 where the details
of the installation methods are
covered.
As Safe or Safer.
Added crawl spaces to specifically
include those areas in the
requirements of this section. Clarified
to refer to Article 300 requirements for
protective means. Added connection
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permissible to secure cables not
smaller than two 6 AWG or three 8
AWG conductors directly to the lower
edges of the joists. Smaller cables
shall be run either through bored holes
in joists or on running boards. NM
cable used on a wall of an unfinished
basement shall be permitted to be
installed in a listed conduit or tubing.
Conduit or tubing shall utilize a
nonmetallic bushing or adapter at the
point the cable enters the raceway.
Metal conduit and tubings and metal
outlet boxes shall be grounded.
basements and crawl spaces, it shall
be permissible to secure cables not
smaller than two 6 AWG or three 8
AWG conductors directly to the lower
edges of the joists. Smaller cables
shall be run either through bored holes
in joists or on running boards. NM
cable installed on the wall of an
unfinished basement shall be permitted
to be installed in a listed conduit or
tubing or shall be protected in
accordance with 300.4. Conduit or
tubing shall be provided with a suitable
insulating bushing or adapter at the
point the cable enters the raceway.
The NM cable sheath shall extend
through the conduit or tubing and into
the outlet or device box not less than 6
mm (1⁄4 in.). The cable shall be
secured within 300 mm (12 in.) of the
point where the cable enters the
conduit or tubing. Metal conduit,
tubing, and metal outlet boxes shall be
connected to an equipment grounding
conductor.
334.80 Ampacity. The ampacity of
Types NM, NMC, and NMS cable shall
be determined in accordance with
310.15. The ampacity shall be in
accordance with the 60°C (140°F)
conductor temperature rating. The
334.80 Ampacity. The ampacity of
Types NM, NMC, and NMS cable shall
be determined in accordance with
310.15. The ampacity shall be in
accordance with the 60°C (140°F)
conductor temperature rating. The
Page 132 of 361
Change Description and Impact to
Worker Safety
requirements for the sheath to assure
a secure protective connection.
Continued emphasis on grounding
conductor to make it clear that there is
a specific function it performs.
As Safe or Safer.
Altered wording to assure that the
cables did not have to be bundled to
require the installation to comply with
this section. Adds requirements for
ampacity adjustment previously not
addressed.
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90°C (194°F) rating shall be permitted
to be used for ampacity derating
purposes, provided the final derated
ampacity does not exceed that for a
60°C (140°F) rated conductor. The
ampacity of Types NM, NMC, and
NMS cable installed in cable tray shall
be determined in accordance with
392.11.
Where more than two NM cables
containing two or more current-carrying
conductors are bundled together and
pass through wood framing that is to
be fire- or draft-stopped using thermal
insulation or sealing foam, the
allowable ampacity of each conductor
shall be adjusted in accordance with
Table 310.15(B)(2)(a).
III. Construction Specifications
2008 NEC
Change Description and Impact to
Worker Safety
90°C (194°F) rating shall be permitted
to be used for ampacity derating
As Safe or Safer.
purposes, provided the final derated
ampacity does not exceed that for a
60°C (140°F) rated conductor. The
ampacity of Types NM, NMC, and
NMS cable installed in cable tray shall
be determined in accordance with
392.11.
Where more than two NM cables
containing two or more current-carrying
conductors are installed, without
maintaining spacing between the
cables, through the same opening in
wood framing that is to be fire- or draftstopped using thermal insulation,
caulk, or sealing foam, the allowable
ampacity of each conductor shall be
adjusted in accordance with Table
310.15(B)(2)(a) and the provisions of
310.15(A)(2), Exception, shall not
apply.
Where more than two NM cables
containing two or more current-carrying
conductors are installed in contact with
thermal insulation without maintaining
spacing between cables, the allowable
ampacity of each conductor shall be
adjusted in accordance with Table
310.15(B)(2)(a).
III. Construction Specifications
Deleted reference to Article 780 as the
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334.104 Conductors. The 600 volt
insulated conductors shall be sizes 14
AWG through 2 AWG copper
conductors or sizes 12 AWG through 2
AWG aluminum or copper-clad
aluminum conductors. The signaling
conductors shall comply with 780.5.
The communication conductors shall
comply with Part V of Article 800.
334.104 Conductors. The 600-volt
insulated conductors shall be sizes 14
AWG through 2 AWG copper
conductors or sizes 12 AWG through 2
AWG aluminum or copper-clad
aluminum conductors. The
communications conductors shall
comply with Part V of Article 800.
334.108 Equipment Grounding. In
addition to the insulated conductors,
the cable shall have an insulated or
bare conductor for equipment
grounding purposes only.
ARTICLE 336
Power and Control Tray Cable:
Type TC
334.108 Equipment Grounding
Conductor. In addition to the insulated
conductors, the cable shall have an
insulated, covered, or bare equipment
grounding conductor.
Article 336
ARTICLE 336
Power and Control Tray Cable:
Type TC
II. Installation
336.10 Uses Permitted. Type TC cable
shall be permitted to be used as
follows:
II. Installation
336.10 Uses Permitted. Type TC cable
shall be permitted to be used as
follows:
(7) In industrial establishments where
the conditions of maintenance and
supervision ensure that only qualified
persons service the installation, and
where the cable is continuously
(7) In industrial establishments where
the conditions of maintenance and
supervision ensure that only qualified
persons service the installation, and
where the cable is continuously
Page 134 of 361
Change Description and Impact to
Worker Safety
article was deleted.
As Safe or Safer.
Continued emphasis on conductor to
make it clear that there is a specific
function it performs.
As Safe or Safer.
Added the exception to allow the
cables to make the less than six foot
transition between trays and
equipment without support, but only in
areas where they will not be subject to
physical damage.
As Safe or Safer.
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supported and protected against
physical damage using mechanical
protection, such as struts, angles, or
channels, Type TC tray cable that
complies with the crush and impact
requirements of Type MC cable and is
identified for such use with the marking
Type TC–ER shall be permitted
between a cable tray and the utilization
equipment or device. The cable shall
be secured at intervals not exceeding
1.8 m (6 ft).
Equipment grounding for the utilization
equipment shall be provided by an
equipment grounding conductor within
the cable. In cables containing
conductors sized 6 AWG or smaller,
the equipment grounding conductor
shall be provided within the cable or, at
the time of installation, one or more
insulated conductors shall be
permanently identified as an
equipment grounding conductor in
accordance with 250.119(B).
supported and protected against
physical damage using mechanical
protection, such as struts, angles, or
channels, Type TC tray cable that
complies with the crush and impact
requirements of Type MC cable and is
identified for such use with the marking
Type TC–ER shall be permitted
between a cable tray and the utilization
equipment or device. The cable shall
be secured at intervals not exceeding
1.8 m (6 ft).
Equipment grounding for the utilization
equipment shall be provided by an
equipment grounding conductor within
the cable. In cables containing
conductors sized 6 AWG or smaller,
the equipment grounding conductor
shall be provided within the cable or, at
the time of installation, one or more
insulated conductors shall be
permanently identified as an
equipment grounding conductor in
accordance with 250.119(B).
Exception: Where not subject to
physical damage, Type TC-ER shall be
permitted to transition between cable
trays and between cable trays and
utilization equipment or devices for a
distance not to exceed 1.8 m (6 ft)
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Change Description and Impact to
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III. Construction Specifications
336.104 Conductors. The insulated
conductors of Type TC tray cable shall
be in sizes 18 AWG through 1000
kcmil copper and sizes 12 AWG
through 1000 kcmil aluminum or
copper-clad aluminum. Insulated
conductors of sizes 14 AWG and larger
copper and sizes 12 AWG and larger
aluminum or copper-clad aluminum
shall be one of the types listed in Table
310.13 or Table 310.62 that is suitable
for branch circuit and feeder circuits or
one that is identified for such use.
2008 NEC
without continuous support. The cable
shall be mechanically supported where
exiting the cable tray to ensure that the
minimum bending radius is not
exceeded.
III. Construction Specifications
II. Installation
336.104 Conductors. The insulated
conductors of Type TC cables shall be
in sizes 18 AWG to 1000 kcmil copper,
nickel, or nickel-coated copper, and
sizes 12 AWG through 1000 kcmil
aluminum or copper-clad aluminum.
Insulated conductors of sizes 14 AWG,
and larger copper, nickel, or nickelcoated copper, and sizes 12 AWG
through 1000 kcmil aluminum or
copper-clad aluminum shall be one of
the types listed in Table 310.13(A) or
Table 310.13(B) that is suitable for
branch circuit and feeder circuits or
one that is identified for such use.
Article 338
II. Installation
338.10 Uses Permitted.
(A) Service-Entrance Conductors.
Service-entrance cable shall be
permitted to be used as serviceentrance conductors and shall be
installed in accordance with 230.6,
338.10 Uses Permitted.
(A) Service-Entrance Conductors.
Service-entrance cable shall be
permitted to be used as serviceentrance conductors and shall be
installed in accordance with 230.6,
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Change Description and Impact to
Worker Safety
Inserted “nickel, or nickel-coated
copper” to allow for newer
manufacturing techniques. Table
references changed to coordinate with
changes in the tables.
As Safe or Safer.
Deleted the allowance for USE cable
to be consistent with the requirements
of underground to surface transitions in
conduit.
As Safe or Safer.
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230.7, and Parts II, III, and IV of Article
230.
Type USE used for service laterals
shall be permitted to emerge from the
ground outside at terminations in meter
bases or other enclosures where
protected in accordance with 300.5(D).
338.10 Uses Permitted.
230.7, and Parts II, III, and IV of Article
230.

(B) Branch Circuits or Feeders.
(B) Branch Circuits or Feeders.
(1) Grounded Conductor Insulated.
Type SE service entrance cables shall
be permitted in wiring systems where
all of the circuit conductors of the cable
are of the rubber covered or
thermoplastic type.
(1) Grounded Conductor Insulated.
Type SE service entrance cables shall
be permitted in wiring systems where
all of the circuit conductors of the cable
are of the thermoset or thermoplastic
type.
As Safe or Safer.
338.10 Uses Permitted.
338.10 Uses Permitted.
(B) Branch Circuits or Feeders.
(B) Branch Circuits or Feeders.
Modified exception to clearly identify
the criteria for use of the referenced
articles.
(2) Grounded Conductor Not Insulated.
Type SE service-entrance cable shall
be permitted for use where the
insulated conductors are used for
circuit wiring and the uninsulated
conductor is used only for equipment
grounding purposes.
(2) Grounded Conductor Not Insulated.
Type SE service-entrance cable shall
be permitted for use where the
insulated conductors are used for
circuit wiring and the uninsulated
conductor is used only for equipment
grounding purposes.
Exception: Uninsulated conductors
Exception: Uninsulated conductors
338.10 Uses Permitted.
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Change Description and Impact to
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Updated to modern manufacturing
techniques and applicability of cable
types.
As Safe or Safer.
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shall be permitted as a grounded
conductor in accordance with 250.140,
250.32, and 225.30 through 225.40.
2008 NEC
338.10 Uses Permitted.
shall be permitted as a grounded
conductor in accordance with 250.32
and 250.140 where the uninsulated
grounded conductor of the cable
originates in service equipment, and
225.30 through 225.40.
338.10 Uses Permitted.
(B) Branch Circuits or Feeders.
(B) Branch Circuits or Feeders.
(4) Installation Methods for Branch
Circuits and Feeders.
(4) Installation Methods for Branch
Circuits and Feeders.
(a) Interior Installations. In addition to
the provisions of this article, Type SE
service-entrance cable used for interior
wiring shall comply with the installation
requirements of Parts I and II of Article
334, excluding 334.80.
(a) Interior Installations. In addition to
the provisions of this article, Type SE
service-entrance cable used for interior
wiring shall comply with the installation
requirements of Part II of Article 334.
Change Description and Impact to
Worker Safety
Deleted “unless used as messengersupported wiring as permitted in Part II
of Article 396” and “Where Type USE
cable emerges from the ground at
terminations, it shall be protected in
accordance with 300.5(D).
Multiconductor service-entrance cable
shall be permitted to be installed as
messenger-supported wiring in
accordance with 225.10 and Part II of
Article 396” and rewrote into 338.12
Uses Not Permitted.
As Safe or Safer.
(b) Exterior Installations. In addition to
the provisions of this article, serviceentrance cable used for feeders or
branch circuits, where installed as
exterior wiring, shall be installed in
accordance with Part I of Article 225.
The cable shall be supported in
accordance with 334.30, unless used
as messenger-supported wiring as
permitted in Part II of Article 396. Type
USE cable installed as underground
(b) Exterior Installations. In addition to
the provisions of this article, serviceentrance cable used for feeders or
branch circuits, where installed as
exterior wiring, shall be installed in
accordance with Part I of Article 225.
The cable shall be supported in
accordance with 334.30. Type USE
cable installed as underground feeder
and branch circuit cable shall comply
with Part II of Article 340.
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feeder and branch circuit cable shall
comply with Part II of Article 340.
Where Type USE cable emerges from
the ground at terminations, it shall be
protected in accordance with 300.5(D).
Multiconductor service-entrance cable
shall be permitted to be installed as
messenger-supported wiring in
accordance with 225.10 and Part II of
Article 396.
2008 NEC
Change Description and Impact to
Worker Safety

338.12 Uses Not Permitted.
Extracted words from 338.10 and
created new section to specify uses
not permitted for service-entrance
cable.
(A) Service-Entrance Cable. Serviceentrance cable (SE) shall not be used
under the following conditions or in the
following locations:
As Safe or Safer.
(1) Where subject to physical damage
unless protected in accordance with
230.50(A)
(2) Underground with or without a
raceway
(3) For exterior branch circuits and
feeder wiring unless the installation
complies with the provisions of Part I of
Article 225 and is supported in
accordance with 334.30 or is used as
messenger-supported wiring as
permitted in Part II of Article 396
(B) Underground Service-Entrance
Cable. Underground service-entrance
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Change Description and Impact to
Worker Safety
Underground Feeder and BranchCircuit Cable: Type UF
cable (USE) shall not be used under
the following conditions or in the
following locations:
(1) For interior wiring
(2) For aboveground installations
except where USE cable emerges from
the ground and is terminated in an
enclosure at an outdoor location and
the cable is protected in accordance
with 300.5(D)
(3) As aerial cable unless it is a
multiconductor cable identified for use
aboveground and installed as
messenger supported wiring in
accordance with 225.10 and Part II
of Article 396
Article 340
Underground Feeder and BranchMade allowance for exceptions
Circuit Cable: Type UF
granted by other Code sections.
340.12 Uses Not Permitted. Type UF
cable shall not be used as follows:
340.12 Uses Not Permitted. Type UF
cable shall not be used as follows:
(7) In hazardous (classified) locations
(7) In any hazardous (classified)
location, except as otherwise permitted
in this Code
340.108 Equipment Grounding
Conductor. In addition to the insulated
conductors, the cable shall be
permitted to have an insulated or bare
equipment grounding conductor.
340.108 Equipment Grounding. In
addition to the insulated conductors,
the cable shall be permitted to have an
insulated or bare conductor for
equipment grounding purposes only.
Page 140 of 361
As Safe or Safer.
Modified to reinforce that an equipment
grounding conductor is the specific
function of the conductor in the cable.
As Safe or Safer.
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Intermediate Metal Conduit: Type IMC
Article 342
Intermediate Metal Conduit: Type IMC
342.30 Securing and Supporting. IMC
shall be installed as a complete system
in accordance with 300.18 and shall be
securely fastened in place and
supported in accordance with
342.30(A) and (B).
342.30 Securing and Supporting.
Rigid Metal Conduit: Type RMC
344.2 Definition.
Rigid Metal Conduit (RMC). A
Change Description and Impact to
Worker Safety
Provides the installer controlled
options for installing unsupported IMC.
342.30 Securing and Supporting. IMC
shall be installed as a complete system As Safe or Safer.
in accordance with 300.18 and shall be
securely fastened in place and
supported in accordance with
342.30(A) and (B), or permitted to be
unsupported in accordance with
342.30(C).
342.30 Securing and Supporting.
New section to specify the allowable
methods for installing IMC
(C) Unsupported Raceways. Where
unsupported.
oversized, concentric or eccentric
knockouts are not encountered, Type
As Safe or Safer.
IMC shall be permitted to be
unsupported where the raceway is not
more than 450 mm (18 in.) and
remains in unbroken lengths (without
coupling). Such raceways shall
terminate in an outlet box, junction box,
device box, cabinet, or other
termination at each end of the
raceway.
Article 344
Rigid Metal Conduit: Type RMC
Replaced “silicon bronze” with “red
brass” to adapt to the current
344.2 Definition.
manufacturing processes and to
identify the more widely used copper
Rigid Metal Conduit (RMC). A
alloys.
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threadable raceway of circular cross
section designed for the physical
protection and routing of conductors
and cables and for use as an
equipment grounding conductor when
installed with its integral or associated
coupling and appropriate fittings. RMC
is generally made of steel (ferrous)
with protective coatings or aluminum
(nonferrous). Special use types are
silicon bronze and stainless steel.
II. Installation
threadable raceway of circular cross
section designed for the physical
protection and routing of conductors
and cables and for use as an
equipment grounding conductor when
installed with its integral or associated
coupling and appropriate fittings. RMC
is generally made of steel (ferrous)
with protective coatings or aluminum
(nonferrous). Special use types are red
brass and stainless steel.
II. Installation
344.10 Uses Permitted.
344.10 Uses Permitted.
(A) All Atmospheric Conditions and
Occupancies. Use of RMC shall be
permitted under all atmospheric
conditions and occupancies. Ferrous
raceways and fittings protected from
corrosion solely by enamel shall be
permitted only indoors and in
occupancies not subject to severe
corrosive influences.
(A) Atmospheric Conditions and
Occupancies.
Change Description and Impact to
Worker Safety
As Safe or Safer.
Expanded section to specifically
identify the applications for the specific
types (galvanized, stainless steel, red
brass, aluminum and ferrous) of RMC
conduits.
As Safe or Safer.
(1) Galvanized Steel and Stainless
Steel RMC. Galvanized steel and
stainless steel RMC shall be permitted
under all atmospheric conditions and
occupancies.
(2) Red Brass RMC. Red brass RMC
shall be permitted to be installed for
direct burial and swimming pool
applications.
(3) Aluminum RMC. Aluminum RMC
shall be permitted to be installed where
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Change Description and Impact to
Worker Safety
judged suitable for the environment.
Rigid aluminum conduit encased in
concrete or in direct contact with the
earth shall be provided with approved
supplementary corrosion protection.
344.10 Uses Permitted.
(B) Corrosion Environments. RMC,
elbows, couplings, and fittings shall be
permitted to be installed in concrete, in
direct contact with the earth, or in
areas subject to severe corrosive
influences where protected by
corrosion protection and judged
suitable for the condition.
(4) Ferrous Raceways and Fittings.
Ferrous raceways and fittings
protected from corrosion solely by
enamel shall be permitted only indoors
and in occupancies not subject to
severe corrosive influences.
344.10 Uses Permitted.
(B) Corrosive Environments.
(1) Galvanized Steel, Stainless Steel,
and Red Brass RMC, Elbows,
Couplings, and Fittings. Galvanized
steel, stainless steel, and red brass
RMC elbows, couplings, and fittings
shall be permitted to be installed in
concrete, in direct contact with the
earth, or in areas subject to severe
corrosive influences where protected
by corrosion protection and judged
suitable for the condition.
(2) Supplementary Protection of
Aluminum RMC. Aluminum RMC shall
be provided with approved
Page 143 of 361
Modified section to specifically address
the properties of each type of RMC
and their applications and to
specifically set requirements for use of
aluminum underground or in concrete.
As Safe or Safer.
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344.10 Uses Permitted.
2008 NEC
supplementary corrosion protection
where encased in concrete or in direct
contact with the earth.
344.10 Uses Permitted.
(C) Cinder Fill. RMC shall be permitted
to be installed in or under cinder fill
where subject to permanent moisture
where protected on all sides by a layer
of noncinder concrete not less than 50
mm (2 in.) thick; where the conduit is
not less than 450 mm (18 in.) under
the fill; or where protected by corrosion
protection and judged suitable for the
condition.
(C) Cinder Fill. Galvanized steel,
stainless steel, and red brass RMC
shall be permitted to be installed in or
under cinder fill where subject to
permanent moisture where protected
on all sides by a layer of noncinder
concrete not less than 50 mm (2 in.)
thick; where the conduit is not less
than 450 mm (18 in.) under the fill; or
where protected by corrosion
protection and judged suitable for the
condition.
344.30 Securing and Supporting. RMC 344.30 Securing and Supporting. RMC
shall be installed as a complete system shall be installed as a complete system
in accordance with 300.18 and shall be in accordance with 300.18 and shall be
securely fastened in place and
securely fastened in place and
supported in accordance with
supported in accordance with
344.30(A) and (B).
344.30(A) and (B) or permitted to be
unsupported in accordance with
344.30(C).
344.30 Securing and Supporting.
344.30 Securing and Supporting.
(C) Unsupported Raceways. Where
oversized, concentric or eccentric
knockouts are not encountered, Type
RMC shall be permitted to be
Page 144 of 361
Change Description and Impact to
Worker Safety
Modified to specifically identify which
types of RMC may be used in cinder fill
locations.
As Safe or Safer.
Added the new alternative (C) to the
allowable support installations.
As Safe or Safer.
New section to specify the allowable
methods for installing RMC
unsupported.
As Safe or Safer.
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Flexible Metal Conduit: Type FMC
348.12 Uses Not Permitted. FMC shall
not be used in the following:
(1) In wet locations unless the
conductors are approved for the
specific conditions and the installation
is such that liquid is not likely to enter
raceways or enclosures to which the
conduit is connected
(2) In hoistways, other than as
permitted in 620.21(A)(1)
(3) In storage battery rooms
(4) In any hazardous (classified)
location other than as permitted
in 501.10(B) and 504.20
(5) Where exposed to materials having
a deteriorating effect on the installed
conductors, such as oil or gasoline
(6) Underground or embedded in
poured concrete or aggregate
(7) Where subject to physical damage
2008 NEC
Change Description and Impact to
Worker Safety
unsupported where the raceway is not
more than 450 mm (18 in.) and
remains in unbroken lengths (without
coupling). Such raceways shall
terminate in an outlet box, junction box,
device box, cabinet, or other
termination at each end of the
raceway.
Article 348
Flexible Metal Conduit: Type FMC
Removed the qualifier to wet locations
to reinforce that FMC is not to be used
348.12 Uses Not Permitted. FMC shall in any wet location and changed the
not be used in the following:
hazardous location requirement to
(1) In wet locations
allow for the other sections of the Code
that contain permissions.
As Safe or Safer.
(2) In hoistways, other than as
permitted in 620.21(A)(1)
(3) In storage battery rooms
(4) In any hazardous (classified)
location except as permitted by other
articles in this Code
(5) Where exposed to materials having
a deteriorating effect on the installed
conductors, such as oil or gasoline
(6) Underground or embedded in
poured concrete or aggregate
(7) Where subject to physical damage
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348.30 Securing and Supporting. FMC
shall be securely fastened in place and
supported in accordance with
348.30(A) and (B).
348.30 Securing and Supporting. FMC
shall be securely fastened in place and
supported in accordance with
348.30(A) and (B).
(A) Securely Fastened. FMC shall be
securely fastened in place by an
approved means within 300 mm (12
in.) of each box, cabinet, conduit body,
or other conduit termination and shall
be supported and secured at intervals
not to exceed 1.4 m (41⁄2 ft).
(A) Securely Fastened. FMC shall be
securely fastened in place by an
approved means within 300 mm (12
in.) of each box, cabinet, conduit body,
or other conduit termination and shall
be supported and secured at intervals
not to exceed 1.4 m (41⁄2 ft).
Exception No. 1: Where FMC is fished.
Exception No. 1: Where FMC is fished
between access points through
concealed spaces in finished buildings
or structures and supporting is
impractical.
Exception No. 2: At terminals where
flexibility is required, lengths shall not
exceed the following:
(1) 900 mm (3 ft) for metric designators
16 through 35 (trade sizes 1⁄2 through
11⁄4)
(2) 1200 mm (4 ft) for metric
designators 41 through 53 (trade sizes
11⁄2 through 2)
(3) 1500 mm (5 ft) for metric
designators 63 (trade size 21⁄2) and
larger
Exception No. 2: Where flexibility is
necessary after installation, lengths
shall not exceed the following:
(1) 900 mm (3 ft) for metric designators
16 through 35 (trade sizes 1⁄2 through
11⁄4)
(2) 1200 mm (4 ft) for metric
designators 41 through 53 (trade sizes
11⁄2 through 2)
(3) 1500 mm (5 ft) for metric
designators 63 (trade size 21⁄2) and
larger
Page 146 of 361
Change Description and Impact to
Worker Safety
Modified Exceptions No. 1 and 2 to
specifically address the fact that the
“fished” FMC is to be for retrofit
installations and does not apply to new
installations.
As Safe or Safer.
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Change Description and Impact to
Worker Safety
348.60 Grounding and Bonding. Where 348.60 Grounding and Bonding. Where Inserted “after installation” to indicate
used to connect equipment where
used to connect equipment where
that the requirement is intended for the
flexibility is required, an equipment
flexibility is required after installation,
installed condition, not for installation
grounding conductor shall be installed. an equipment grounding conductor
purposes. This change limits the use of
Where flexibility is not required, FMC
shall be installed.
FMC for equipment grounding.
shall be permitted to be used as an
Where flexibility is not required after
equipment grounding conductor when
installation, FMC shall be permitted to
As Safe or Safer.
installed in accordance with
be used as an equipment grounding
250.118(5).
conductor when installed in
Where required or installed, equipment accordance with 250.118(5).
grounding conductors shall be installed Where required or installed, equipment
in accordance with 250.134(B).
grounding conductors shall be installed
Where required or installed, equipment in accordance with 250.134(B).
bonding jumpers shall be installed in
Where required or installed, equipment
accordance with 250.102.
bonding jumpers shall be installed in
accordance with 250.102.
Article 350
Liquidtight Flexible Metal Conduit:
Liquidtight Flexible Metal Conduit:
Modified Exceptions No. 1 and 2 to
Type LFMC
Type LFMC
specifically address the fact that the
“fished” LFMC is to be for retrofit
350.30 Securing and Supporting.
350.30 Securing and Supporting.
installations and does not apply to new
LFMC shall be securely fastened in
LFMC shall be securely fastened in
installations.
place and supported in accordance
place and supported in accordance
with 350.30(A) and (B).
with 350.30(A) and (B).
As Safe or Safer.
(A) Securely Fastened. LFMC shall be (A) Securely Fastened. LFMC shall be
securely fastened in place by an
securely fastened in place by an
approved means within 300 mm (12
approved means within 300 mm (12
in.) of each box, cabinet, conduit body, in.) of each box, cabinet, conduit body,
or other conduit termination and shall
or other conduit termination and shall
be supported and secured at intervals
be supported and secured at intervals
not to exceed 1.4 m (41⁄2 ft).
not to exceed 1.4 m (41⁄2 ft).
Page 147 of 361
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Exception No. 1: Where LFMC is
fished.
2008 NEC
Change Description and Impact to
Worker Safety
Exception No. 1: Where LFMC is
fished between access points through
concealed spaces in finished buildings
or structures and supporting is
impractical.
Exception No. 2: Where flexibility is
necessary after installation, lengths
shall not exceed the following:
(1) 900 mm (3 ft) for metric designators
16 through 35 (trade sizes 1⁄2 through
11⁄4)
(2) 1200 mm (4 ft) for metric
designators 41 through 53 (trade sizes
11⁄2 through 2)
(3) 1500 mm (5 ft) for metric
designators 63 (trade size 21⁄2) and
larger
350.60 Grounding and Bonding. Where 350.60 Grounding and Bonding. Where
used to connect equipment where
used to connect equipment where
flexibility is required, an equipment
flexibility is required after installation,
grounding conductor shall be installed. an equipment grounding conductor
Where flexibility is not required, LFMC shall be installed.
shall be permitted to be used as an
Where flexibility is not required after
equipment grounding conductor when
installation, LFMC shall be permitted to
installed in accordance with
be used as an equipment grounding
250.118(6).
conductor when installed in
accordance with 250.118(6).
Article 352
Page 148 of 361
Inserted “after installation” to indicate
that the requirement is intended for the
installed condition, not for installation
purposes.
As Safe or Safer.
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2008 NEC
Rigid Nonmetallic Conduit: Type RNC
Rigid Polyvinyl Chloride Conduit:
Type PVC
I. General
I. General
352.1 Scope. This article covers the
use, installation, and construction
specifications for rigid nonmetallic
conduit (RNC) and associated fittings.
352.1 Scope. This article covers the
use, installation, and construction
specifications for rigid polyvinyl
chloride conduit (PVC) and associated
fittings.
352.2 Definition.
352.2 Definition.
Rigid Nonmetallic Conduit (RNC). A
nonmetallic raceway of circular cross
section, with integral or associated
couplings, connectors, and fittings for
the installation of electrical conductors
and cables.
Rigid Polyvinyl Chloride Conduit
(PVC). A rigid nonmetallic conduit
(RNC) of circular cross section, with
integral or associated couplings,
connectors, and fittings for the
installation of electrical conductors and
cables.
II. Installation
II. Installation
352.10 Uses Permitted. The use of
RNC shall be permitted in accordance
with 352.10(A) through (H).
352.10 Uses Permitted. The use of
PVC conduit shall be permitted in
accordance with 352.10(A) through
Page 149 of 361
Change Description and Impact to
Worker Safety
This article was changed to specifically
address rigid polyvinyl chloride conduit
(PVC) as opposed to other types of
conduit some believed to fit the
requirements rigid nonmetallic conduit
(RNC).
As Safe or Safer.
This article was changed to specifically
address rigid polyvinyl chloride conduit
(PVC) as opposed to other types of
conduit some believed to fit the
requirements rigid nonmetallic conduit
(RNC).
As Safe or Safer.
Throughout Article 352, PVC and
polyvinyl chloride were inserted in lieu
of RNC and rigid nonmetallic and will
not be compared individually. The
remaining changes in the article are
addressed in the subsequent table
sections in this document.
Clarified intent that conduit may be
installed exposed but must be
identified for use in areas of physical
damage.
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(H).
(F) Exposed. RNC shall be permitted
for exposed work where not subject to
physical damage if identified for such
use.
352.10 Uses Permitted.
(G) Underground Installations. For
underground installations, see 300.5
and 300.50.
352.12 Uses Not Permitted. RNC shall
not be used under the following
conditions.
(A) Hazardous (Classified) Locations.
(1) In hazardous (classified) locations,
except as permitted in 503.10(A),
504.20, 514.8 Exception No. 2, and
515.8
(2) In Class I, Division 2 locations,
except as permitted in 501.10(B)(3)
352.30 Securing and Supporting. RNC
shall be installed as a complete system
as provided in 300.18 and shall be
fastened so that movement from
(F) Exposed. PVC conduit shall be
permitted for exposed work. PVC
conduit used exposed in areas of
physical damage shall be identified for
the use.
352.10 Uses Permitted.
(G) Underground Installations. For
underground installations,
homogenous and nonhomogenous
PVC shall be permitted for direct burial
and underground encased in concrete.
See 300.5 and 300.50.
352.12 Uses Not Permitted. PVC
conduit shall not be used under the
conditions specified in 352.12(A)
through (F).
(A) Hazardous (Classified) Locations.
In any hazardous (classified) location,
except as permitted by other articles of
this Code.
Change Description and Impact to
Worker Safety
As Safe or Safer.
Clarified intent that both homogenous
and nonhomogenous PVC can be
used underground and in concrete.
As Safe or Safer.
Changed the hazardous location
requirement to allow for the other
sections of the Code that contain
permissions.
As Safe or Safer.

352.30 Securing and Supporting. PVC
conduit shall be installed as a complete
system as provided in 300.18 and shall
be fastened so that movement from
Page 150 of 361
Part of the overall effort to address
securing and supporting conduits and
to include conditions for not supporting
by reference to new section.
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thermal expansion or contraction is
permitted. RNC shall be securely
fastened and supported in accordance
with 352.30(A) and (B).
352.30 Securing and Supporting.
2008 NEC
thermal expansion or contraction is
permitted. PVC conduit shall be
securely fastened and supported in
accordance with 352.30(A) and (B) or
permitted to be unsupported in
accordance with 352.30(C).
352.30 Securing and Supporting.
Change Description and Impact to
Worker Safety
As Safe or Safer.
New section to specify the allowable
methods for installing PVC
unsupported.
(C) Unsupported Raceways. Where
oversized, concentric or eccentric
knockouts are not encountered, PVC
As Safe or Safer.
conduit shall be permitted to be
unsupported where the raceway is not
more than 450 mm (18 in.) and
remains in unbroken lengths (without
coupling). Such raceway shall
terminate in an outlet box, junction box,
device box, cabinet, or other
termination at each end of the
raceway.
III. Construction Specifications
III. Construction Specifications
This article was changed to specifically
address rigid polyvinyl chloride conduit
352.100 Construction. RNC and fittings 352.100 Construction. PVC conduit
(PVC) as opposed to other types of
shall be composed of suitable
shall be made of rigid (nonplasticized)
conduit some believed to fit the
nonmetallic material that is resistant to polyvinyl chloride (PVC). PVC conduit
requirements rigid nonmetallic conduit
moisture and chemical atmospheres.
and fittings shall be composed of
(RNC).
For use above ground, it shall also be
suitable nonmetallic material that is
flame retardant, resistant to impact and resistant to moisture and chemical
As Safe or Safer.
crushing, resistant to distortion from
atmospheres. For use aboveground, it
heat under conditions likely to be
shall also be flame retardant, resistant
encountered in service, and resistant
to impact and crushing, resistant to
Page 151 of 361
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to low temperature and sunlight
effects. For use underground, the
material shall be acceptably resistant
to moisture and corrosive agents and
shall be of sufficient strength to
withstand abuse, such as by impact
and crushing, in handling and during
installation. Where intended for direct
burial, without encasement in concrete,
the material shall also be capable of
withstanding continued loading that is
likely to be encountered after
installation.
2008 NEC
Change Description and Impact to
Worker Safety
II. Installation
distortion from heat under conditions
likely to be encountered in service, and
resistant to low temperature and
sunlight effects. For use underground,
the material shall be acceptably
resistant to moisture and corrosive
agents and shall be of sufficient
strength to withstand abuse, such as
by impact and crushing, in handling
and during installation. Where intended
for direct burial, without encasement in
concrete, the material shall also be
capable of withstanding continued
loading that is likely to be encountered
after installation.
Article 353
High Density Polyethylene Conduit:
Added provision (5) to address the
Type HDPE Conduit
need to allow above ground
installations with the exclusions
II. Installation
addressed in 353.12 enforced.
353.10 Uses Permitted. The use of
HDPE conduit shall be permitted under
the following conditions:
(1) In discrete lengths or in continuous
lengths from a reel
(2) In locations subject to severe
corrosive influences as covered in
300.6 and where subject to chemicals
for which the conduit is listed
(3) In cinder fill
353.10 Uses Permitted. The use of
HDPE conduit shall be permitted under
the following conditions:
(1) In discrete lengths or in continuous
lengths from a reel
(2) In locations subject to severe
corrosive influences as covered in
300.6 and where subject to chemicals
for which the conduit is listed
(3) In cinder fill
High Density Polyethylene Conduit:
Type HDPE Conduit
Page 152 of 361
As Safe or Safer.
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(4) In direct burial installations in earth
or concrete
(5) Above ground, except as prohibited
in 353.12, where encased in not less
than 50 mm (2 in.) of concrete.
353.12 Uses Not Permitted. HDPE
353.12 Uses Not Permitted. HDPE
conduit shall not be
conduit shall not be used under the
used under the following conditions:
following conditions:
(1) Where exposed
(1) Where exposed
(2) Within a building
(2) Within a building
(3) In hazardous (classified) locations, (3) In any hazardous (classified)
except as permitted in 504.20
location, except as permitted by other
articles in this Code
(4) Where subject to ambient
(4) Where subject to ambient
temperatures in excess of 50°C
temperatures in excess of 50°C
(122°F) unless listed otherwise
(122°F) unless listed otherwise
(5) For conductors or cables operating (5) For conductors or cables operating
at a temperature higher than the HDPE at a temperature higher than the HDPE
conduit listed operating temperature
conduit listed operating temperature
rating
rating
353.20 Size.
353.20 Size.
Change Description and Impact to
Worker Safety
(4) In direct burial installations in earth
or concrete
(B) Maximum. HDPE conduit larger
than metric designator 103 (trade size
4) shall not be used.
Nonmetallic Underground Conduit with
Conductors: Type NUCC
(B) Maximum. HDPE conduit larger
than metric designator 155 (trade size
6) shall not be used.
Article 354
Nonmetallic Underground Conduit with
Conductors: Type NUCC
II. Installation
II. Installation
Page 153 of 361
Made allowance for exceptions
granted by other Code sections rather
than a specific single section.
As Safe or Safer.
Allows for larger size limit of HDPE
conduit to be utilized.
As Safe or Safer.
Added provision (5) to address the
need to allow above ground
installations with the exclusions
addressed in 354.12 enforced.
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354.10 Uses Permitted. The use of
NUCC and fittings
shall be permitted in the following:
(1) For direct burial underground
installation (For minimum cover
requirements, see Table 300.5 and
Table 300.50 under Rigid Nonmetallic
Conduit.)
(2) Encased or embedded in concrete
(3) In cinder fill
(4) In underground locations subject to
severe corrosive influences as covered
in 300.6 and where subject to
chemicals for which the assembly is
specifically approved
354.10 Uses Permitted. The use of
NUCC and fittings shall be permitted in
the following:
(1) For direct burial underground
installation (For minimum cover
requirements, see Table 300.5 and
Table 300.50 under Rigid Nonmetallic
Conduit.)
(2) Encased or embedded in concrete
(3) In cinder fill
(4) In underground locations subject to
severe corrosive influences as covered
in 300.6 and where subject to
chemicals for which the assembly is
specifically approved
(5) Aboveground, except as prohibited
in 354.12, where encased in not less
than 50 mm (2 in.) of concrete.
354.12 Uses Not Permitted. NUCC
shall not be used in the following:
(1) In exposed locations
(2) Inside buildings
354.12 Uses Not Permitted. NUCC
shall not be used in the following:
(1) In exposed locations
(2) Inside buildings
Change Description and Impact to
Worker Safety
As Safe or Safer.
Made allowance for exceptions
granted by other Code sections rather
than addressing specific sections.
As Safe or Safer.
Exception: The conductor or the cable
portion of the assembly, where
suitable, shall be permitted to extend
within the building for termination
purposes in accordance with 300.3.
Exception: The conductor or the cable
portion of the assembly, where
suitable, shall be permitted to extend
within the building for termination
purposes in accordance with 300.3.
(3) In hazardous (classified) locations
except as permitted by 503.10(A),
(3) In any hazardous (classified)
location, except as permitted
Page 154 of 361
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504.20, 514.8, and 515.8, and in Class
I, Division 2 locations as permitted in
501.10(B)(3)
2008 NEC
Change Description and Impact to
Worker Safety
by other articles of this Code
Liquidtight Flexible Nonmetallic
Conduit: Type LFNC
Article 356
Liquidtight Flexible Nonmetallic
Conduit: Type LFNC
New section to address use in
concrete encased installations.
II. Installation
II. Installation
As Safe or Safer.
356.10 Uses Permitted. LFNC shall be
permitted to be used in exposed or
concealed locations for the following
purposes:
356.10 Uses Permitted. LFNC shall be
permitted to be used in exposed or
concealed locations for the following
purposes:
356.12 Uses Not Permitted. LFNC
shall not be used as follows:
(7) For encasement in concrete where
listed for direct burial and installed in
compliance with 356.42.
356.12 Uses Not Permitted. LFNC
shall not be used as follows:
(5) In any hazardous (classified)
location other than as permitted in
501.10(B), 502.10(A) and (B),
503.10(A), and 504.20
356.20 Size.
(A) Minimum. LFNC smaller than
metric designator 16 (trade size 1⁄2)
shall not be used unless permitted in
356.20(A)(1) through (A)(3) for metric
designator 12 (trade size 3⁄8).
(1) For enclosing the leads of motors
(5) In any hazardous (classified)
location, except as permitted by other
articles in this Code
356.20 Size.
(A) Minimum. LFNC smaller than
metric designator 16 (trade size 1⁄2)
shall not be used unless permitted in
356.20(A)(1) or (A)(2) for metric
designator 12 (trade size 3⁄8).
(1) For enclosing the leads of motors
Page 155 of 361
Made allowance for exceptions
granted by other Code sections rather
than addressing specific sections.
As Safe or Safer.
Deleted (3) due to the daisy chain
reference provided in Article 600 that
stated follow Chapter 3 which is
already a requirement.
As Safe or Safer.
70 2008 851 Evaluation
2005 NEC
as permitted in 430.245(B)
(2) In lengths not exceeding 1.8 m
(6 ft ) as part of a listed assembly for
tap connections to luminaires (lighting
fixtures) as required in 410.67(C), or
for utilization equipment
(3) For electric sign conductors in
accordance with 600.32(A)
2008 NEC
Change Description and Impact to
Worker Safety
as permitted in 430.245(B)
(2) In lengths not exceeding 1.8 m
(6 ft ) as part of a listed assembly for
tap connections to luminaires as
required in 410.117(C), or for utilization
equipment

Electrical Metallic Tubing: Type EMT
Article 358
Electrical Metallic Tubing: Type EMT
358.12 Uses Not Permitted. EMT shall
not be used under the following
conditions:
358.12 Uses Not Permitted. EMT shall
not be used under the following
conditions:
(4) In any hazardous (classified)
location except as permitted by 502.10,
503.10, and 504.20
358.30 Securing and Supporting. EMT
shall be installed as a complete system
in accordance with 300.18 and shall be
securely fastened in place and
supported in accordance with
358.30(A) and (B).
(4) In any hazardous (classified)
location except as permitted by other
articles in this Code.
358.30 Securing and Supporting. EMT
shall be installed as a complete system
in accordance with 300.18 and shall be
securely fastened in place and
supported in accordance with
358.30(A) and (B) or permitted to be
unsupported in accordance with
358.30(C).
(C) Unsupported Raceways. Where
oversized, concentric or eccentric
knockouts are not encountered, Type
EMT shall be permitted to be
unsupported where the raceway is not
Page 156 of 361
Made allowance for exceptions
granted by other Code sections rather
than addressing specific sections.
As Safe or Safer.
Part of the overall effort to address
securing and supporting conduits and
to include conditions for not supporting
by reference to new section.
As Safe or Safer.
New section to specify the allowable
methods for installing EMT
unsupported.
As Safe or Safer.
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2008 NEC
Electrical Nonmetallic Tubing:
Type ENT
more than 450 mm (18 in.) and
remains in unbroken lengths (without
coupling). Such raceways shall
terminate in an outlet box, device box,
cabinet, or other termination at each
end of the raceway.
Article 362
Electrical Nonmetallic Tubing:
Type ENT
362.12 Uses Not Permitted. ENT shall
not be used in the following:
(1) In hazardous (classified) locations,
except as permitted by 504.20 and
505.15(A)(1)
362.30 Securing and Supporting. ENT
shall be installed as a complete system
in accordance with 300.18 and shall be
securely fastened in place and
supported in accordance with
362.30(A) and (B).
362.12 Uses Not Permitted. ENT shall
not be used in the following:
(1) In any hazardous (classified)
location, except as permitted by other
articles in this Code
362.30 Securing and Supporting. ENT
shall be installed as a complete system
in accordance with 300.18 and shall be
securely fastened in place and
supported in accordance with
362.30(A) and (B).
(A) Securely Fastened. ENT shall be
securely fastened at intervals not
exceeding 900 mm (3 ft). In addition,
ENT shall be securely fastened in
place within 900 mm (3 ft) of each
outlet box, device box, junction box,
cabinet, or fitting where it terminates.
(A) Securely Fastened. ENT shall be
securely fastened at intervals not
exceeding 900 mm (3 ft). In addition,
ENT shall be securely fastened in
place within 900 mm (3 ft) of each
outlet box, device box, junction box,
cabinet, or fitting where it terminates.
Exception No. 3: For concealed work in
Page 157 of 361
Change Description and Impact to
Worker Safety
Made allowance for exceptions
granted by other Code sections rather
than addressing specific sections.
As Safe or Safer.
New exception (3) added to address
specific requirements for fished ENT
conduits.
As Safe or Safer.
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2008 NEC
Auxiliary Gutters
finished buildings or prefinished wall
panels where such securing is
impracticable, unbroken lengths
(without coupling) of ENT shall be
permitted to be fished.
362.60 Grounding. Where equipment
grounding is required, a separate
equipment grounding conductor shall
be installed in the raceway in
compliance with Article 250, Part VI.
Article 366
Auxiliary Gutters
366.2 Definitions.
366.2 Definitions.
Metallic Auxiliary Gutters. Sheet metal
enclosures with hinged or removable
covers for housing and protecting
electric wires, cable, and busbars in
which conductors are laid in place after
the wireway has been installed as a
complete system.
Metallic Auxiliary Gutter. A sheet metal
enclosure used to supplement wiring
spaces at meter centers, distribution
centers, switchboards, and similar
points of wiring systems. The
enclosure has hinged or removable
covers for housing and protecting
electrical wires, cable, and busbars.
The enclosure is designed for
conductors to be laid or set in place
after the enclosures have been
installed as a complete system.
Nonmetallic Auxiliary Gutters. Flame
retardant, nonmetallic enclosures with
removable covers for housing and
Nonmetallic Auxiliary Gutter. A flame
retardant, nonmetallic enclosure used
to supplement wiring spaces at meter
362.60 Grounding. Where equipment
grounding is required, a separate
equipment grounding conductor shall
be installed in the raceway.
Page 158 of 361
Change Description and Impact to
Worker Safety
Added the specific requirements for
the grounding conductor.
Will actually improve worker safety
working on these systems.
Rewrite of the two definitions to
specifically address the function and
installation techniques required for
auxiliary gutters.
As Safe or Safer.
70 2008 851 Evaluation
2005 NEC
2008 NEC
protecting electric wires, cable, and
busbars in which conductors are laid in
place after the wireway has been
installed as a complete system.
centers, distribution centers,
switchboards, and similar points of
wiring systems. The enclosure has
hinged or removable covers for
housing and protecting electrical wires,
cable, and busbars. The enclosure is
designed for conductors to be laid or
set in place after the enclosures have
been installed as a complete system.
II. Installation
II. Installation
366.10 Uses Permitted. Auxiliary
gutters shall be permitted to
supplement wiring spaces at meter
centers, distribution centers,
switchboards, and similar points of
wiring systems and may enclose
conductors or busbars.
366.10 Uses Permitted.

(A) Sheet Metal Auxiliary Gutters.
366.60 Grounding. Metal auxiliary
gutters shall be grounded.
Busways
(A) Sheet Metal Auxiliary Gutters.
366.60 Grounding. Metal auxiliary
gutters shall be connected to an
equipment grounding conductor(s), to
an equipment bonding jumper, or to
the grounded conductor where
permitted or required by 250.92(B)(1)
or 250.142.
Article 368
Busways
368.56 Branches from Busways.
368.56 Branches from Busways.
Page 159 of 361
Change Description and Impact to
Worker Safety
Moved verbiage into the definition
section for the two types of gutters.
As Safe or Safer.
Specifies the grounding requirements
for gutters.
Will actually improve worker safety
working on these systems.
Modified (8) for the PVC changes and
inserted “Type RTRC reinforced
thermosetting resin conduit” as (9).
70 2008 851 Evaluation
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2008 NEC
Branches from busways shall be
permitted to be made in accordance
with 368.56(A), (B), and (C).
Branches from busways shall be
permitted to be made in accordance
with 368.56(A), (B), and (C).
(A) General. Branches from busways
shall be permitted to use any of the
following wiring methods:
(A) General. Branches from busways
shall be permitted to use any of the
following wiring methods:
(1) Type AC armored cable
(2) Type MC metal-clad cable
(3) Type MI mineral-insulated, metalsheathed cable
(4) Type IMC intermediate metal
conduit
(5) Type RMC rigid metal conduit
(6) Type FMC flexible metal conduit
(7) Type LFMC liquidtight flexible metal
conduit
(8) Type RNC rigid nonmetallic conduit
(9) Type LFNC liquidtight flexible
nonmetal conduit
(10) Type EMT electrical metallic
tubing
(11) Type ENT electrical nonmetallic
tubing
(12) Busways
(13) Strut-type channel raceway
(14) Surface metal raceways
(15) Surface nonmetallic raceways
(1) Type AC armored cable
(2) Type MC metal-clad cable
(3) Type MI mineral-insulated, metalsheathed cable
(4) Type IMC intermediate metal
conduit
(5) Type RMC rigid metal conduit
(6) Type FMC flexible metal conduit
(7) Type LFMC liquidtight flexible metal
conduit
(8) Type PVC rigid polyvinyl chloride
conduit
(9) Type RTRC reinforced
thermosetting resin conduit
(10) Type LFNC liquidtight flexible
nonmetallic conduit
(11) Type EMT electrical metallic
tubing
(12) Type ENT electrical nonmetallic
tubing
(13) Busways
(14) Strut-type channel raceway
(15) Surface metal raceway
Page 160 of 361
Change Description and Impact to
Worker Safety
As Safe or Safer.
70 2008 851 Evaluation
2005 NEC
368.60 Grounding. Busway shall be
grounded.
Metal Wireways
376.22 Number of Conductors. The
sum of the cross-sectional areas of all
contained conductors at any cross
section of a wireway shall not exceed
20 percent of the interior crosssectional area of the wireway. The
derating factors in 310.15(B)(2)(a) shall
be applied only where the number of
current-carrying conductors, including
neutral conductors classified as
current-carrying under the provisions of
310.15(B)(4), exceeds 30. Conductors
for signaling circuits or controller
conductors between a motor and its
starter and used only for starting duty
shall not be considered as currentcarrying conductors.
2008 NEC
(16) Surface nonmetallic raceway
368.60 Grounding. Busway shall be
connected to an equipment grounding
conductor(s), to an equipment bonding
jumper, or to the grounded conductor
where permitted or required by
250.92(B)(1) or 250.142.
Article 376
Metal Wireways
376.22 Number of Conductors and
Ampacity. The number of conductors
and their ampacity shall comply with
376.22(A) and (B).
Change Description and Impact to
Worker Safety
Specifies the grounding requirements
for busways.
Will actually improve worker safety
working on these systems.
Expanded version of 376.22 points to
the same basic requirements, but more
appropriately addresses the basis for
the limitation of the number of
conductors allowed.
As Safe or Safer.
(A) Cross-Sectional Areas of Wireway.
The sum of the cross-sectional areas
of all contained conductors at any
cross section of a wireway shall not
exceed 20 percent of the interior crosssectional area of the wireway.
(B) Adjustment Factors. The
adjustment factors in 310.15(B)(2)(a)
shall be applied only where the number
of current-carrying conductors,
including neutral conductors classified
as current-carrying under the
provisions of 310.15(B)(4), exceeds
30. Conductors for signaling circuits or
controller conductors between a motor
Page 161 of 361
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376.56 Splices, Taps, and Power
Distribution Blocks.
(B) Power Distribution Blocks.
(4) Live Parts. Power distribution
blocks shall not have exposed live
parts in the wireway after installation.
III. Construction Specifications
2008 NEC
Change Description and Impact to
Worker Safety
and its starter and used only for
starting duty shall not be considered as
current-carrying conductors.
376.56 Splices, Taps, and Power
Modified to clarify the confusion
Distribution Blocks.
surrounding what qualified as
“exposed” since, with the cover on, the
(B) Power Distribution Blocks.
live parts were not exposed outside of
the wireway.
(4) Live Parts. Power distribution
blocks shall not have uninsulated live
May actually provide a safer work
parts exposed within a wireway,
environment for the electrical worker.
whether or not the wireway cover is
installed.
III. Construction Specifications
New section addressing the specific
requirements for wireway construction.
376.100 Construction.
May actually provide a safer work
(A) Electrical and Mechanical
environment for the electrical worker.
Continuity. Wireways shall be
constructed and installed so that
adequate electrical and mechanical
continuity of the complete system is
secured.
(B) Substantial Construction. Wireways
shall be of substantial construction and
shall provide a complete enclosure for
the contained conductors. All surfaces,
both interior and exterior, shall be
suitably protected from corrosion.
Corner joints shall be made tight, and
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Change Description and Impact to
Worker Safety
where the assembly is held together by
rivets, bolts, or screws, such fasteners
shall be spaced not more than 300 mm
(12 in.) apart.
(C) Smooth Rounded Edges. Suitable
bushings, shields, or fittings having
smooth, rounded edges shall be
provided where conductors pass
between wireways, through partitions,
around bends, between wireways and
cabinets or junction boxes, and at
other locations where necessary to
prevent abrasion of the insulation of
the conductors.
Nonmetallic Extensions
(D) Covers. Covers shall be securely
fastened to the wireway.
Article 382
Nonmetallic Extensions
382.2 Definition.
382.2 Definitions.
Nonmetallic Extension. An assembly of
two insulated conductors within a
nonmetallic jacket or an extruded
thermoplastic covering. The
classification includes surface
extensions intended for mounting
directly on the surface of walls or
ceilings.
Concealable Nonmetallic Extension. A
listed assembly of two, three, or four
insulated circuit conductors within a
nonmetallic jacket, an extruded
As Safe or Safer.
thermoplastic covering, or a sealed
nonmetallic covering. The classification
includes surface extensions intended
for mounting directly on the surface of
Page 163 of 361
Expands the original definition to
include “listed assembly”, the fact that
the unit may be concealed by dry wall
finishing or similar materials and that a
sealed non-metallic covering is
acceptable.
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382.10 Uses Permitted. Nonmetallic
extensions shall be permitted only in
accordance with 382.10(A), (B), and
(C).
(A) From an Existing Outlet. The
extension shall be from an existing
outlet on a 15- or 20-ampere branch
circuit.
2008 NEC
walls or ceilings, and concealed with
paint, texture, joint compound, plaster,
wallpaper, tile, wall paneling, or other
similar materials.
382.6 Listing Requirements.
Concealable nonmetallic extensions
and associated fittings and devices
shall be listed. The starting/source tap
device for the extension shall contain
and provide the following protection for
all load-side extensions and devices.
(1) Supplementary overcurrent
protection
(2) Level of protection equivalent to a
Class A GFCI
(3) Level of protection equivalent to a
portable GFCI
(4) Line and load-side miswire
protection
(5) Provide protection from the effects
of arc faults
382.10 Uses Permitted. Nonmetallic
extensions shall be permitted only in
accordance with 382.10(A), (B), and
(C).
Change Description and Impact to
Worker Safety
New section to clearly state the listing
requirements.
As Safe or Safer.
Provides specific guidance for
determining the grounding
requirements for these units.
May actually provide a safer work
(A) From an Existing Outlet. The
environment for the electrical worker.
extension shall be from an existing
outlet on a 15- or 20-ampere branch
circuit. Where a concealable
nonmetallic extension originates from a
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382.10 Uses Permitted.
(B) Exposed and in a Dry Location.
The extension shall be run exposed
and in a dry location.
382.10 Uses Permitted.
2008 NEC
non–grounding-type receptacle, the
installation shall comply with
250.130(C), 406.3(D)(3)(b), or
406.3(D)(3)(c).
382.10 Uses Permitted.
(B) Exposed and in a Dry Location.
The extension shall be run exposed, or
concealed as permitted in 382.15, and
in a dry location.
382.10 Uses Permitted.
(C) Residential or Offices. For
nonmetallic surface extensions
mounted directly on the surface of
walls or ceilings, the building shall be
occupied for residential or office
purposes and shall not exceed three
floors above grade.
(C) Residential or Offices. For
nonmetallic surface extensions
mounted directly on the surface of
walls or ceilings, the building shall be
occupied for residential or office
purposes and shall not exceed three
floors above grade. Where identified
for the use, concealable nonmetallic
extensions shall be permitted more
than three floors above grade.
382.15 Exposed. One or more
extensions shall be permitted to be run
in any direction from an existing outlet,
but not on the floor or within 50 mm (2
in.) from the floor.
382.15 Exposed.
(A) Nonmetallic Extensions. One or
more extensions shall be permitted to
be run in any direction from an existing
outlet, but not on the floor or within 50
mm (2 in.) from the floor.
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Change Description and Impact to
Worker Safety
Allows for the new concealed
installation provisions.
As Safe or Safer.
Allows for the new concealed
installation provisions.
As Safe or Safer.
Allows for the new concealed
installation provisions.
As Safe or Safer.
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(B) Concealable Nonmetallic
Extensions. Where identified for the
use, nonmetallic extensions may be
concealed with paint, texture,
concealing compound, plaster,
wallpaper, tile, wall paneling, or other
similar materials and installed per
382.15(A).
382.26 Bends. A bend that reduces the 382.26 Bends.
normal spacing between the
conductors shall be covered with a cap (A) Nonmetallic Extensions. A bend
to protect the assembly from physical
that reduces the normal spacing
damage.
between the conductors shall be
covered with a cap to protect the
assembly from physical damage.
382.30 Securing and Supporting.
Nonmetallic surface extensions shall
be secured in place by approved
means at intervals not exceeding 200
mm (8 in.), with an allowance for 300
mm (12 in.) to the first fastening where
the connection to the supplying outlet
is by means of an attachment plug.
There shall be at least one fastening
between each two adjacent outlets
(B) Concealable Nonmetallic
Extensions. Concealable extensions
shall be permitted to be folded back
over themselves and flattened as
required for installation.
382.30 Securing and Supporting.
(A) Nonmetallic Extensions.
Nonmetallic surface extensions shall
be secured in place by approved
means at intervals not exceeding 200
mm (8 in.), with an allowance for 300
mm (12 in.) to the first fastening where
the connection to the supplying outlet
is by means of an attachment plug.
Page 166 of 361
Change Description and Impact to
Worker Safety
Allows for the new concealed
installation provisions.
As Safe or Safer.
Allows for the new concealed
installation provisions.
As Safe or Safer.
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supplied. An extension shall be
attached to only woodwork or plaster
finish and shall not be in contact with
any metal work or other conductive
material other than with metal plates
on receptacles.
2008 NEC
Change Description and Impact to
Worker Safety
There shall be at least one fastening
between each two adjacent outlets
supplied. An extension shall be
attached to only woodwork or plaster
finish and shall not be in contact with
any metal work or other conductive
material other than with metal plates
on receptacles.
(B) Concealable Nonmetallic
Extensions. All surface mounted
concealable nonmetallic extension
components shall be firmly anchored to
the wall or ceiling using an adhesive or
mechanical anchoring system
identified for this use.
382.40 Boxes and Fittings. Each run
382.40 Boxes and Fittings. Each run
Allows for termination of the run in a
shall terminate in a fitting that covers
shall terminate in a fitting, connector,
connector or box in addition to a fitting.
the end of the assembly. All fittings and or box that covers the end of the
devices shall be of a type identified for assembly. All fittings, connectors, and
As Safe or Safer.
the use.
devices shall be of a type identified for
the use.
382.42 Devices.
(A) Receptacles. All receptacles,
receptacle housings, and selfcontained devices used with
concealable nonmetallic extensions
shall be identified for this use.
Page 167 of 361
New section to cover the devices used
with non-metallic extensions.
As Safe or Safer.
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Change Description and Impact to
Worker Safety
(B) Receptacles and Housings.
Receptacle housings and selfcontained devices designed either for
surface or for recessed mounting shall
be permitted for use with concealable
nonmetallic extensions. Receptacle
housings and self contained devices
shall incorporate means for facilitating
entry and termination of concealable
nonmetallic extensions and for
electrically connecting the housing or
device. Receptacle and self-contained
devices shall comply with 406.3. Power
and communications outlets installed
together in common housing shall be
permitted in accordance with
800.133(A)(1)(c), Exception No. 2.
III. Construction Specifications
New section to address the new
(Concealable Nonmetallic Extensions
Concealable Nonmetallic Extensions
only)
provisions.
382.100 Construction. Concealable
nonmetallic extensions shall be a
multilayer flat conductor design
consisting of a center ungrounded
conductor enclosed by a sectioned
grounded conductor, and an overall
sectioned grounding conductor.
382.104 Flat Conductors. Concealable
nonmetallic extensions shall be
Page 168 of 361
As Safe or Safer.
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constructed, using flat copper
conductors equivalent to 14 AWG or
12 AWG conductor sizes, and
constructed per 382.104(A), (B), and
(C).
(A) Ungrounded Conductor (Center
Layer). The ungrounded conductor
shall consist of one or more
ungrounded flat conductor(s) enclosed
per 382.104(B) and (C) and identified
in accordance with 310.12(C).
(B) Grounded Conductor (Inner
Sectioned Layers). The grounded
conductor shall consist of two
sectioned inner flat conductors that
enclose the center ungrounded
conductor(s). The sectioned grounded
conductor shall be enclosed by the
sectioned grounding conductor and
identified in accordance with 200.6.
(C) Grounding Conductor (Outer
Sectioned Layers). The grounding
conductor shall consist of two overall
sectioned conductors that enclose the
grounded conductor and ungrounded
conductor(s) and shall comply with
250.4(A)(5). The grounding conductor
layers shall be identified by any one of
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Change Description and Impact to
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the following methods:
(1) As permitted in 250.119
(2) A clear covering
(3) One or more continuous green
stripes or hash marks
(4) The term ″Equipment Ground″
printed at regular intervals throughout
the cable
382.112 Insulation. The ungrounded
and grounded flat conductor layers
shall be individually insulated and
comply with 310.10. The grounding
conductor shall be covered or
insulated.
382.120 Marking.
(A) Cable. Concealable nonmetallic
extensions shall be clearly and durably
marked on both sides at intervals of
not more than 610 mm (24 in.) with the
information required by 310.11(A) and
with the following additional
information:
(1) Material of conductors
(2) Maximum temperature rating
(3) Ampacity
(B) Conductor Identification.
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Change Description and Impact to
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Conductors shall be clearly and
durably identified on both sides
throughout their length as specified in
382.104.
Article 388
Surface Nonmetallic Raceways
388.30 Securing and Supporting.
Surface nonmetallic raceways shall be
supported at intervals in accordance
with the manufacturer’s installation
instructions.
388.56 Splices and Taps. Splices and
388.56 Splices and Taps. Splices and
taps shall be permitted in surface
taps shall be permitted in surface
nonmetallic raceways having a
nonmetallic raceways having a cover
removable cover that is accessible
capable of being opened in place that
after installation. The conductors,
is accessible after installation. The
including splices and taps, shall not fill conductors, including splices and taps,
the raceway to more than 75 percent of shall not fill the raceway to more than
its area at that point. Splices and taps
75 percent of its area at that point.
in surface nonmetallic raceways
Splices and taps in surface nonmetallic
without removable covers shall be
raceways without covers capable of
made only in boxes. All splices and
being opened in place shall be made
taps shall be made by approved
only in boxes. All splices and taps shall
methods.
be made by approved methods.
Article 392
Cable Trays
Cable Trays
Change Description and Impact to
Worker Safety
New section to address securing and
supporting requirements of these
raceways.
As Safe or Safer.
Inserted “capable of being opened in
place” to differentiate from covers that
actually separate from the raceway.
As Safe or Safer.
392.7 Grounding.
392.7 Grounding.
Modified to reinforce the grounding
conductor requirements for tray
installations.
(A) Metallic Cable Trays. Metallic cable
(A) Metallic Cable Trays. Metallic cable
May actually provide a safer work
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trays that support electrical conductors
shall be grounded as required for
conductor enclosures in accordance
with 250.96.
trays that support electrical conductors
shall be grounded as required for
conductor enclosures in accordance
with 250.96 and Part IV of Article 250.
(B) Steel or Aluminum Cable Tray
Systems. Steel or aluminum cable tray
systems shall be permitted to be used
as equipment grounding conductors,
provided that all the following
requirements are met:
(B) Steel or Aluminum Cable Tray
Systems. Steel or aluminum cable tray
systems shall be permitted to be used
as equipment grounding conductors,
provided all the following requirements
are met:
(1) The cable tray sections and fittings
shall be identified for grounding
purposes.
392.8 Cable Installation.
(1) The cable tray sections and fittings
are identified as an equipment
grounding conductor.
392.8 Cable Installation.
(A) Cable Splices. Cable splices made
and insulated by approved methods
shall be permitted to be located within
a cable tray, provided they are
accessible and do not project above
the side rails.
392.9 Number of Multiconductor
Cables, Rated 2000 Volts or Less, in
Cable Trays.
(A) Cable Splices. Cable splices made
and insulated by approved methods
shall be permitted to be located within
a cable tray, provided they are
accessible. Splices shall be permitted
to project above the side rails where
not subject to physical damage.
392.9 Number of Multiconductor
Cables, Rated 2000 Volts or Less, in
Cable Trays.
(A) Any Mixture of Cables.
(A) Any Mixture of Cables.
(1) Where all of the cables are 4/0
(1) Where all of the cables are 4/0
Change Description and Impact to
Worker Safety
environment for the electrical worker.
Makes an allowance for splices where
they are not subject to physical
damage.
As Safe or Safer.
Provides for the tray width
requirements not previously referenced
when ampacity may impact the
physical relationships.
As Safe or Safer.
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AWG or larger, the sum of the
diameters of all cables shall not
exceed the cable tray width, and the
cables shall be installed in a single
layer.
392.11 Ampacity of Cables, Rated
2000 Volts or Less, in Cable Trays.
2008 NEC
AWG or larger, the sum of the
diameters of all cables shall not
exceed the cable tray width, and the
cables shall be installed in a single
layer. Where the cable ampacity is
determined according to 392.11(A)(3),
the cable tray width shall not be less
than the sum of the diameters of the
cables and the sum of the required
spacing widths between the cables.
392.11 Ampacity of Cables, Rated
2000 Volts or Less, in Cable Trays.
Change Description and Impact to
Worker Safety
New section to specifically address
requirements for the situation where
multiconductor and single conductor
(C) Combinations of Multiconductor
cables must be installed in the same
and Single-Conductor Cables. Where a tray.
cable tray contains a combination of
multiconductor and single-conductor
As Safe or Safer.
cables, the allowable ampacities shall
be as given in 392.11(A) for
multiconductor cables and 392.11(B)
for single-conductor cables, provided
that the following conditions apply:
(1) The sum of the multiconductor
cable fill area as a percentage of the
allowable fill area for the tray
calculated per 392.9, and the singleconductor cable fill area as a
percentage of the allowable fill area for
the tray calculated per 392.10, totals
not more than 100 percent.
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Messenger-Supported Wiring
396.30 Messenger Support. The
messenger shall be supported at dead
ends and at intermediate locations so
as to eliminate tension on the
conductors. The conductors shall not
be permitted to come into contact with
the messenger supports or any
structural members, walls, or pipes.
2008 NEC
(2) Multiconductor cables are installed
according to 392.9 and singleconductor cables are installed
according to 392.10 and 392.8(D) and
(E).
Article 396
Messenger-Supported Wiring
396.30 Messenger.
(A) Support. The messenger shall be
supported at dead ends and at
intermediate locations so as to
eliminate tension on the conductors.
The conductors shall not be permitted
to come into contact with the
messenger supports or any structural
members, walls, or pipes.
(B) Neutral Conductor. Where the
messenger is used as a neutral
conductor, it shall comply with the
requirements of 225.4, 250.184(A),
250.184(B)(7), and 250.186(B).
(C) Equipment Grounding Conductor.
Where the messenger is used as an
equipment grounding conductor, it
shall comply with the requirements of
250.32(B), 250.118, 250.184(B)(8),
Page 174 of 361
Change Description and Impact to
Worker Safety
New sections to provide the
requirements for the situations where
the messenger is used for either a
neutral conductor or an equipment
grounding conductor.
As Safe or Safer.
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400.5 Ampacities for Flexible Cords
and Cables.
and 250.186(D).
Article 400
400.5 Ampacities for Flexible Cords
and Cables.
(B) Ultimate Insulation Temperature. In
no case shall conductors be
associated together in such a way with
respect to the kind of circuit, the wiring
method used, or the number of
conductors such that the limiting
temperature of the conductors is
exceeded.
A neutral conductor that carries only
the unbalanced current from other
conductors of the same circuit shall not
be required to meet the requirements
of a current-carrying conductor.
In a 3-wire circuit consisting of two
phase wires and the neutral of a 4wire, 3-phase, wye-connected system,
a common conductor carries
approximately the same current as the
line-to-neutral currents of the other
conductors and shall be considered to
be a current-carrying conductor.
On a 4-wire, 3-phase, wye circuit
where the major portion of the load
consists of nonlinear loads, there are
harmonic currents present in the
neutral conductor and the neutral shall
(B) Ultimate Insulation Temperature. In
no case shall conductors be
associated together in such a way with
respect to the kind of circuit, the wiring
method used, or the number of
conductors such that the limiting
temperature of the conductors is
exceeded.
A neutral conductor that carries only
the unbalanced current from other
conductors of the same circuit shall not
be required to meet the requirements
of a current-carrying conductor.
In a 3-wire circuit consisting of two
phase conductors and the neutral
conductor of a 4-wire, 3-phase, wye
connected system, a common
conductor carries approximately the
same current as the line-to-neutral
currents of the other conductors and
shall be considered to be a currentcarrying conductor.
On a 4-wire, 3-phase, wye circuit
where more than 50 percent of the
load consists of nonlinear loads, there
are harmonic currents present in the
Page 175 of 361
Change Description and Impact to
Worker Safety
Continued emphasis on conductors
and the functional requirements of
them and, in addition, provides specific
criteria for determination of neutral
conductor as a current carrying
conductor.
As Safe or Safer.
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be considered to be a current-carrying
conductor.
An equipment grounding conductor
shall not be considered a currentcarrying conductor.
Where a single conductor is used for
both equipment grounding and to carry
unbalanced current from other
conductors, as provided for in 250.140
for electric ranges and electric clothes
dryers, it shall not be considered as a
current-carrying conductor.
400.23 Equipment Grounding
Conductor Identification.
A conductor intended to be used as an
equipment grounding conductor shall
have a continuous identifying marker
readily distinguishing it from the other
conductor or conductors. Conductors
having a continuous green color or a
continuous green color with one or
more yellow stripes shall not be used
for other than equipment grounding
purposes. The identifying marker shall
consist of one of the methods in
400.23(A) or 400.23(B).
III. Portable Cables Over 600 Volts,
Nominal
neutral conductor and the neutral
conductor shall be considered to be a
current carrying conductor.
An equipment grounding conductor
shall not be considered a currentcarrying conductor.
Where a single conductor is used for
both equipment grounding and to carry
unbalanced current from other
conductors, as provided for in 250.140
for electric ranges and electric clothes
dryers, it shall not be considered as a
current-carrying conductor.
400.23 Equipment Grounding
Conductor Identification.
A conductor intended to be used as an
equipment grounding conductor shall
have a continuous identifying marker
readily distinguishing it from the other
conductor or conductors. Conductors
having a continuous green color or
a continuous green color with one or
more yellow stripes shall not be used
for other than equipment grounding
conductors. The identifying marker
shall consist of one of the methods in
400.23(A) or (B).
III. Portable Cables Over 600 Volts,
Nominal
400.30 Scope. This part applies to
400.30 Scope. Part III applies to
Page 176 of 361
Change Description and Impact to
Worker Safety
Continued emphasis on equipment
grounding conductors and the
functional requirements of them.
As Safe or Safer.
Reduced minimum size of conductors
due to improved manufacturing
processes and eliminated the
exception since it no longer applies.
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multiconductor portable cables used to
connect mobile equipment and
machinery.
multiconductor portable cables used to
connect mobile equipment and
machinery.
400.31 Construction.
(A) Conductors. The conductors shall
be 8 AWG copper or larger and shall
employ flexible stranding.
400.31 Construction.
(A) Conductors. The conductors shall
be 12 AWG copper or larger and shall
employ flexible stranding.
Exception: The size of the insulated
ground-check conductor of Type G-GC
cables shall be not smaller than 10
AWG.
400.32 Shielding. All shields shall be
grounded.

400.33 Grounding. Grounding
conductors shall be connected in
accordance with Part V of Article 250.
400.32 Shielding. All shields shall be
connected to an equipment grounding
conductor.
400.33 Equipment Grounding
Conductors. Equipment grounding
conductors shall be connected in
accordance with Parts VI and VII of
Article 250.
Change Description and Impact to
Worker Safety
As Safe or Safer.
Continuing with the emphasis on
“connected to an equipment grounding
conductor….” versus just “grounded”
provides assurance of a connection to
ground.
May actually improve worker safety.
Continuing with the emphasis on
“equipment grounding conductor” and
specific reference sections provide
assurance of a good connection to
ground.
May actually improve worker safety.
Article 404
Switches
Switches
404.4 Wet Locations. A switch or
404.4 Damp or Wet Locations. A
Page 177 of 361
Expanded the section to include damp
locations and to distinguish between
surface-mounted and flush-mounted
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circuit breaker in a wet location or
outside of a building shall be enclosed
in a weatherproof enclosure or cabinet
that shall comply with 312.2(A).
Switches shall not be installed within
wet locations in tub or shower spaces
unless installed as part of a listed tub
or shower assembly.
404.8 Accessibility and Grouping.
2008 NEC
Change Description and Impact to
Worker Safety
requirements.
surface-mounted switch or circuit
breaker in a damp or wet location shall
be enclosed in a weatherproof
As Safe or Safer.
enclosure or cabinet that shall comply
with 312.2. A flush-mounted switch or
circuit breaker in a damp or wet
location shall be equipped with a
weatherproof cover. Switches shall not
be installed within wet locations in tub
or shower spaces unless installed as
part of a listed tub or shower assembly.
404.8 Accessibility and Grouping.
Continuing the expansion of this
section from last cycle, section (C) was
(C) Multipole Snap Switches. A
added to address multipole, generalmultipole, general-use snap switch
use snap switches.
shall not be permitted to be fed from
more than a single circuit unless it is
As Safe or Safer.
listed and marked as a two-circuit or
three-circuit switch, or unless its
voltage rating is not less than the
nominal line-to-line voltage of the
system supplying the circuits.
404.9 Provisions for General-Use Snap 404.9 Provisions for General-Use Snap Inserted “connected to an equipment
Switches.
Switches.
grounding conductor” in lieu of
“effectively grounded” and similar
(B) Grounding. Snap switches,
(B) Grounding. Snap switches,
changes to specifically provide
including dimmer and similar control
including dimmer and similar control
requirements for a connection to an
switches, shall be effectively grounded switches, shall be connected to an
equipment grounding conductor.
and shall provide a means to ground
equipment grounding conductor and
metal faceplates, whether or not a
shall provide a means to connect metal May actually improve worker safety.
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metal faceplate is installed. Snap
switches shall be considered
effectively grounded if either of the
following conditions is met:
faceplates to the equipment grounding
conductor, whether or not a metal
faceplate is installed. Snap switches
shall be considered to be part of an
effective ground-fault current path if
either of the following conditions is
met:
(1) The switch is mounted with metal
screws to a metal box or to a
nonmetallic box with integral means for
grounding devices.
(1) The switch is mounted with metal
screws to a metal box or metal cover
that is connected to an equipment
grounding conductor or to a
nonmetallic box with integral means for
connecting to an equipment grounding
conductor.
(2) An equipment grounding conductor
or equipment bonding jumper is
connected to an equipment grounding
termination of the snap switch.
(2) An equipment grounding conductor
or equipment bonding jumper is
connected to an equipment grounding
termination of the snap switch.
Exception to (B): Where no grounding
means exists within the snap-switch
enclosure or where the wiring method
does not include or provide an
equipment ground, a snap switch
without a grounding connection shall
be permitted for replacement purposes
only. A snap switch wired under the
provisions of this exception and
located within reach of earth, grade,
Exception to (B): Where no means
exists within the snapswitch enclosure
for connecting to the equipment
grounding conductor or where the
wiring method does not include or
provide an equipment grounding
conductor, a snap switch without a
connection to an equipment grounding
conductor shall be permitted for
replacement purposes only. A snap
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switch wired under the provisions of
this exception and located within reach
of earth, grade, conducting floors, or
other conducting surfaces shall be
provided with a faceplate of
nonconducting, noncombustible
material or shall be protected by a
ground-fault circuit interrupter.
404.12 Grounding of Enclosures. Metal 404.12 Grounding of Enclosures. Metal
enclosures for switches or circuit
enclosures for switches or circuit
breakers shall be grounded as
breakers shall be connected to an
specified in Article 250. Where
equipment grounding conductor as
nonmetallic enclosures are used with
specified in Part IV of Article 250.
metal raceways or metal-armored
Metal enclosures for switches or circuit
cables, provision shall be made for
breakers used as service equipment
grounding continuity.
shall comply with the provisions of Part
V of Article 250. Where nonmetallic
enclosures are used with metal
raceways or metal-armored cables,
provision shall be made for connecting
the equipment grounding conductor(s).
Except as covered in 404.9(B),
Except as covered in 404.9(B),
Exception, nonmetallic boxes for
Exception, nonmetallic boxes for
switches shall be installed with a wiring switches shall be installed with a wiring
method that provides or includes an
method that provides or includes an
equipment ground.
equipment grounding conductor.
Article 406
Receptacles, Cord Connectors,
Receptacles, Cord Connectors,
and Attachment Plugs (Caps)
and Attachment Plugs (Caps)
Change Description and Impact to
Worker Safety
conducting floors, or other conducting
surfaces shall be provided with a
faceplate of nonconducting,
noncombustible material or shall be
protected by a groundfault circuit
interrupter.
406.2 Receptacle Rating and Type.
406.2 Receptacle Rating and Type.
Page 180 of 361
Inserted “connected to an equipment
grounding conductor” in lieu of
“grounded” and similar changes to
specifically provide requirements for a
connection to an equipment grounding
conductor.
May actually improve worker safety.
Continued emphasis on equipment
grounding conductor connection
versus just grounding.
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(D) Isolated Ground Receptacles.
Receptacles incorporating an isolated
grounding connection intended for the
reduction of electrical noise
(electromagnetic interference) as
permitted in 250.146(D) shall be
identified by an orange triangle located
on the face of the receptacle.
(D) Isolated Ground Receptacles.
Receptacles incorporating an isolated
grounding conductor connection
intended for the reduction of electrical
noise (electromagnetic interference) as
permitted in 250.146(D) shall be
identified by an orange triangle located
on the face of the receptacle.
(1) Isolated Equipment Grounding
Conductor Required. Receptacles so
identified shall be used only with
grounding conductors that are isolated
in accordance with 250.146(D).
406.3 General Installation
Requirements.
(1) Isolated Equipment Grounding
Conductor Required. Receptacles so
identified shall be used only with
equipment grounding conductors that
are isolated in accordance with
250.146(D).
406.3 General Installation
Requirements.
(B) To Be Grounded. Receptacles and
cord connectors that have equipment
grounding conductor contacts shall
have those contacts connected to an
equipment grounding conductor.
406.3 General Installation
Requirements.
(C) Methods of Grounding. The
grounding contacts of receptacles and
cord connectors shall be grounded by
connection to the equipment grounding
conductor of the circuit supplying the
(C) Methods of Grounding. The
equipment grounding conductor
contacts of receptacles and cord
connectors shall be grounded by
connection to the equipment grounding
406.3 General Installation
Requirements.
(B) To Be Grounded. Receptacles and
cord connectors that have grounding
contacts shall have those contacts
effectively grounded.
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Change Description and Impact to
Worker Safety
May actually improve worker safety.
Continued emphasis on equipment
grounding conductor connection
versus just “effectively grounded.”
May actually improve worker safety.
Continued emphasis on equipment
grounding conductor connection
versus just grounding.
May actually improve worker safety.
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Change Description and Impact to
Worker Safety
receptacle or cord connector.
conductor of the circuit supplying the
receptacle or cord connector.
The branch-circuit wiring method shall
include or provide an equipmentgrounding conductor to which the
grounding contacts of the receptacle or
cord connector are connected.
406.3 General Installation
Requirements.
The branch-circuit wiring method shall
include or provide an equipment
grounding conductor to which the
equipment grounding conductor
contacts of the receptacle or cord
connector are connected.
406.3 General Installation
Requirements.
(D) Replacements. Replacement of
receptacles shall comply with
406.3(D)(1), (D)(2), and (D)(3) as
applicable.
(D) Replacements. Replacement of
receptacles shall comply with
406.3(D)(1), (D)(2), and (D)(3) as
applicable.
(1) Grounding-Type Receptacles.
Where a grounding means exists in the
receptacle enclosure or a grounding
conductor is installed in accordance
with 250.130(C), grounding-type
receptacles shall be used and shall be
connected to the grounding conductor
in accordance with 406.3(C) or
250.130(C).
(1) Grounding-Type Receptacles.
Where a grounding means exists in the
receptacle enclosure or an equipment
grounding conductor is installed in
accordance with 250.130(C),
grounding-type receptacles shall be
used and shall be connected to the
equipment grounding conductor in
accordance with 406.3(C) or
250.130(C).
406.3 General Installation
Continued emphasis on equipment
Requirements.
grounding conductor connection
versus just grounding.
(D) Replacements.
406.3 General Installation
Requirements.
(D) Replacements.
Page 182 of 361
Continued emphasis on equipment
grounding conductor connection
versus just grounding.
May actually improve worker safety.
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(3) Non–grounding-Type Receptacles.
Where grounding means does not exist
in the receptacle enclosure, the
installation shall comply with (D)(3)(a),
(D)(3)(b), or (D)(3)(c).
406.4 Receptacle Mounting.
(3) Non–Grounding-Type Receptacles.
Where attachment to an equipment
grounding conductor does not exist in
the receptacle enclosure, the
installation shall comply with (D)(3)(a),
(D)(3)(b), or (D)(3)(c).
406.4 Receptacle Mounting.
(D) Position of Receptacle Faces. After
installation, receptacle faces shall be
flush with or project from faceplates of
insulating material and shall project a
minimum of 0.4 mm (0.015 in.) from
metal faceplates.
(D) Position of Receptacle Faces. After
installation, receptacle faces shall be
flush with or project from faceplates of
insulating material and shall project a
minimum of 0.4 mm (0.015 in.) from
metal faceplates.
Exception No. 1: Listed kits or
assemblies encompassing receptacles
and nonmetallic faceplates that cover
the receptacle face, where the plate
cannot be installed on any other
receptacle, shall be permitted.
Exception: Listed kits or assemblies
encompassing receptacles and
nonmetallic faceplates that cover the
receptacle face, where the plate
cannot be installed on any other
receptacle, shall be permitted.
Exception No. 2: Listed nonmetallic
faceplates that cover the receptacle
face to a maximum thickness of 1 mm
(0.040 in.) shall be permitted.
406.4 Receptacle Mounting.

406.4 Receptacle Mounting.
(G) Voltage Between Adjacent
Devices. A receptacle shall not be
Page 183 of 361
Change Description and Impact to
Worker Safety
May actually improve worker safety.
Deleted Exception No. 2 to eliminate
the misuse of the nonmetallic
faceplates.
As Safe or Safer.
New section (G) to address grouping
of receptacles and the allowable
voltage potential difference between
them.
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406.6 Attachment Plugs, Cord
Connectors, and Flanged Surface
Devices.
(B) Connection of Attachment Plugs.
Attachment plugs shall be installed so
that their prongs, blades, or pins are
not energized unless inserted into an
energized receptacle. No receptacle
shall be installed so as to require the
insertion of an energized attachment
plug as its source of supply.
2008 NEC
grouped or ganged in enclosures with
other receptacles, snap switches, or
similar devices, unless they are
arranged so that the voltage between
adjacent devices does not exceed 300
volts, or unless they are installed in
enclosures equipped with identified,
securely installed barriers between
adjacent devices.
406.6 Attachment Plugs, Cord
Connectors, and Flanged Surface
Devices.
406.8 Receptacles in Damp or Wet
Locations.
(B) Connection of Attachment Plugs.
Attachment plugs shall be installed so
that their prongs, blades, or pins are
not energized unless inserted into an
energized receptacle or cord
connectors. No receptacle shall be
installed so as to require the insertion
of an energized attachment plug as its
source of supply.
406.8 Receptacles in Damp or Wet
Locations.
(A) Damp Locations. A receptacle
installed outdoors in a location
protected from the weather or in other
damp locations shall have an
enclosure for the receptacle that is
weatherproof when the receptacle is
(A) Damp Locations. A receptacle
installed outdoors in a location
protected from the weather or in other
damp locations shall have an
enclosure for the receptacle that is
weatherproof when the receptacle is
Page 184 of 361
Change Description and Impact to
Worker Safety
May actually improve worker safety.
Added cord connectors to allow for
extension cord use for cord and plug
connected devices.
As Safe or Safer.
Added listing requirements for the
common devices addressed by this
section.
May actually improve worker safety.
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covered (attachment plug cap not
inserted and receptacle covers closed).
An installation suitable for wet
locations shall also be considered
suitable for damp locations.
A receptacle shall be considered to be
in a location protected from the
weather where located under roofed
open porches, canopies, marquees,
and the like, and will not be subjected
to a beating rain or water runoff.
406.8 Receptacles in Damp or Wet
Locations.
(B) Wet Locations.
(1) 15- and 20-Ampere Receptacles in
a Wet Location. 15- and 20-ampere,
125- and 250-volt receptacles installed
in a wet location shall have an
enclosure that is weatherproof whether
or not the attachment plug cap is
inserted.
2008 NEC
Change Description and Impact to
Worker Safety
covered (attachment plug cap not
inserted and receptacle covers closed).
An installation suitable for wet
locations shall also be considered
suitable for damp locations.
A receptacle shall be considered to be
in a location protected from the
weather where located under roofed
open porches, canopies, marquees,
and the like, and will not be subjected
to a beating rain or water runoff. All 15and 20-ampere, 125- and 250-volt
nonlocking receptacles shall be a listed
weather-resistant type.
406.8 Receptacles in Damp or Wet
Added listing requirements for the
Locations.
common devices addressed by this
section and made allowances for wash
(B) Wet Locations.
down areas.
(1) 15- and 20-Ampere Receptacles in
a Wet Location. 15- and 20-ampere,
As Safe or Safer.
125- and 250-volt receptacles installed
in a wet location shall have an
enclosure that is weatherproof whether
or not the attachment plug cap is
inserted. All 15- and 20-ampere, 125and 250-volt nonlocking receptacles
shall be listed weather-resistant type.
Exception: 15- and 20-ampere, 125through 250-volt receptacles installed
in a wet location and subject to routine
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406.9 Grounding-Type Receptacles,
Adapters, Cord Connectors, and
Attachment Plugs.
high-pressure spray washing shall be
permitted to have an enclosure that is
weatherproof when the attachment
plug is removed.
406.9 Grounding-Type Receptacles,
Adapters, Cord Connectors, and
Attachment Plugs.
(B) Grounding-Pole Identification.
Grounding-type receptacles, adapters,
cord connections, and attachment
plugs shall have a means for
connection of a grounding conductor to
the grounding pole.
406.9 Grounding-Type Receptacles,
Adapters, Cord Connectors, and
Attachment Plugs.
(B) Grounding-Pole Identification.
Grounding-type receptacles, adapters,
cord connections, and attachment
plugs shall have a means for
connection of an equipment grounding
conductor to the grounding pole.
406.9 Grounding-Type Receptacles,
Adapters, Cord Connectors, and
Attachment Plugs.
(D) Grounding-Pole Requirements.
Grounding-type attachment plugs and
mating cord connectors and
receptacles shall be designed such
that the equipment grounding
connection is made before the currentcarrying connections. Grounding-type
devices shall be so designed that
grounding poles of attachment plugs
cannot be brought into contact with
current-carrying parts of receptacles or
cord connectors.
406.11 Tamper-Resistant Receptacles
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Change Description and Impact to
Worker Safety
Inserted “an equipment” here and in
(3) and (4) to address the specific
requirement that the grounding pole
must be connected to the equipment
grounding conductor.
As Safe or Safer.
Inserted “equipment” here to address
the specific requirement that the
grounding pole must be connected to
the equipment grounding conductor.
As Safe or Safer.
New section added to address the
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Switchboards and Panelboards
in Dwelling Units. In all areas specified
in 210.52, all 125-volt, 15- and 20ampere receptacles shall be listed
tamper-resistant receptacles.
Article 408
Switchboards and Panelboards
408.3 Support and Arrangement of
Busbars and Conductors.
408.3 Support and Arrangement of
Busbars and Conductors.
(D) Terminals. In switchboards and
panelboards, load terminals for field
wiring, including grounded circuit
conductor load terminals and
connections to the ground bus for load
equipment grounding conductors, shall
be so located that it is not necessary to
reach across or beyond an uninsulated
ungrounded line bus in order to make
connections.
(D) Terminals. In switchboards and
panelboards, load terminals for field
wiring, including grounded circuit
conductor load terminals and
connections to the equipment
grounding conductor bus for load
equipment grounding conductors, shall
be so located that it is not necessary to
reach across or beyond an uninsulated
ungrounded line bus in order to make
connections.
408.3 Support and Arrangement of
408.3 Support and Arrangement of
Busbars and Conductors.
Busbars and Conductors.
(F) Minimum Wire-Bending Space. The (F) High-Leg Identification. A
minimum wire-bending space at
switchboard or panelboard containing
terminals and minimum gutter space
a 4-wire, delta-connected system
provided in panelboards and
where the midpoint of one phase
switchboards shall be as required in
winding is grounded shall be legibly
312.6.
and permanently field marked as
follows:
“Caution _____ Phase Has _____
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Change Description and Impact to
Worker Safety
requirement for tamper resistant
receptacle installations.
As Safe or Safer.
Inserted “equipment grounding
conductor” here to continue with the
emphasis on connections to the
equipment grounding conductor, not
just a ground.
As Safe or Safer.
Inserted new section (F) to specifically
address the requirements for High-Leg
identification.
May actually improve worker safety.
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Change Description and Impact to
Worker Safety
Volts to Ground”
(G) Minimum Wire-Bending Space.
The minimum wire-bending space at
terminals and minimum gutter space
provided in panelboards and
switchboards shall be as required in
312.6.
408.4 Circuit Directory or Circuit
408.4 Circuit Directory or Circuit
Identification. Every circuit and circuit
Identification. Every circuit and circuit
modification shall be legibly identified
modification shall be legibly identified
as to its clear, evident, and specific
as to its clear, evident, and specific
purpose or use. The identification shall purpose or use. The identification shall
include sufficient detail to allow each
include sufficient detail to allow each
circuit to be distinguished from all
circuit to be distinguished from all
others. The identification shall be
others. Spare positions that contain
included in a circuit directory that is
unused overcurrent devices or
located on the face or inside of the
switches shall be described
panel door in the case of a panelboard, accordingly. The identification shall be
and located at each switch on a
included in a circuit directory that is
switchboard.
located on the face or inside of the
panel door in the case of a panelboard,
and located at each switch on a
switchboard. No circuit shall be
described in a manner that depends on
transient conditions of occupancy.
III. Panelboards
III. Panelboards
408.30 General. All panelboards shall
have a rating not less than the
minimum feeder capacity required for
408.30 General. All panelboards shall
have a rating not less than the
minimum feeder capacity required for
Page 188 of 361
Reinforced requirements for panel
directories to include specific direction
for spare circuits and to assure the
identification is understandable
regardless of who occupies the
premises.
May actually improve worker safety.
Part III of Article 408 has been
reworked such that portions of 408.30,
408.34, 408.35 and 408.36 have been
transformed into the new 408.30,
408.36, 408.54 and 408.58. Section
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the load calculated in accordance with
Article 220.
the load calculated in accordance with
Parts II, III, IV, or V of Article 220 as
applicable.
Panelboards shall be durably marked
by the manufacturer with the voltage
and the current rating and the number
of phases for which they are designed
and with the manufacturer’s name or
trademark in such a manner so as to
be visible after installation, without
disturbing the interior parts or wiring.
408.34 Classification of Panelboards.
Panelboards shall be classified for the
purposes of this article as either
lighting and appliance branch-circuit
panelboards or power panelboards,
based on their content. A lighting and
appliance branch circuit is a branch
circuit that has a connection to the
neutral of the panelboard and that has
overcurrent protection of 30 amperes
or less in one or more conductors.

Change Description and Impact to
Worker Safety
408.30 was shortened by moving the
second phrase into new section 408.58
and adding specific references to
address the applicable sections of
Article 220.
As Safe or Safer.

Part III of Article 408 has been
reworked such that portions of 408.30,
408.34, 408.35 and 408.36 have been
transformed into the new 408.30,
408.36, 408.54 and 408.58.
Section 408.34 was removed since
panelboards are panelboards and not
classified as lighting or power.
As Safe or Safer.
(A) Lighting and Appliance BranchCircuit Panelboard. A lighting and
appliance branch-circuit panelboard is
one having more than 10 percent of its
overcurrent devices protecting lighting
and appliance branch circuits.
(B) Power Panelboard. A power
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panelboard is one having 10 percent or
fewer of its overcurrent devices
protecting lighting and appliance
branch circuits.
408.35 Number of Overcurrent Devices 
on One Panelboard. Not more than 42
overcurrent devices (other than those
provided for in the mains) of a lighting
and appliance branch-circuit
panelboard shall be installed in any
one cabinet or cutout box.
A lighting and appliance branch-circuit
panelboard shall be provided with
physical means to prevent the
installation of more overcurrent devices
than that number for which the
panelboard was designed, rated, and
approved.
For the purposes of this article, a 2pole circuit breaker shall be considered
two overcurrent devices; a 3-pole
circuit breaker shall be considered
three overcurrent devices.
408.36 Overcurrent Protection.
408.36 Overcurrent Protection. In
addition to the requirement of 408.30,
(A) Lighting and Appliance Brancha panelboard shall be protected by an
Circuit Panelboard Individually
overcurrent protective device having a
Protected. Each lighting and appliance rating not greater than that of the
branch-circuit panelboard shall be
panelboard. This overcurrent protective
individually protected on the supply
device shall be located within or at any
side by not more than two main circuit
point on the supply side of the
Page 190 of 361
Change Description and Impact to
Worker Safety
Part III of Article 408 has been
reworked such that portions of 408.30,
408.34, 408.35 and 408.36 have been
transformed into the new 408.30,
408.36, 408.54 and 408.58.
Section 408.35 was transformed into
408.54 and modified to remove the
specific 42 breaker limit and rely on the
maximum number of devices for which
the panelboard was designed, rated,
and listed.
As Safe or Safer.
Part III of Article 408 has been
reworked such that portions of 408.30,
408.34, 408.35 and 408.36 have been
transformed into the new 408.30,
408.36 and 408.58.
Total rework of this section provides
some of the old wording, but
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breakers or two sets of fuses having a
combined rating not greater than that
of the panelboard.
Exception No. 1: Individual protection
for a lighting and appliance panelboard
shall not be required if the panelboard
feeder has overcurrent protection not
greater than the rating of the
panelboard.
Exception No. 2: For existing
installations, individual protection for
lighting and appliance branch-circuit
panelboards shall not be required
where such panelboards are used as
service equipment in supplying an
individual residential occupancy.
2008 NEC
panelboard.
Exception No. 1: Individual protection
shall not be required for a panelboard
used as service equipment with
multiple disconnecting means in
accordance with 230.71. In
panelboards protected by three or
more main circuit breakers or sets of
fuses, the circuit breakers or sets of
fuses shall not supply a second bus
structure within the same panelboard
assembly.
Exception No. 2: Individual protection
shall not be required for a panelboard
protected on its supply side by two
main circuit breakers or two sets of
fuses having a combined rating not
greater than that of the panelboard. A
panelboard constructed or wired under
this exception shall not contain more
than 42 overcurrent devices. For the
purposes of determining the maximum
of 42 overcurrent devices, a 2-pole or a
3-pole circuit breaker shall be
considered as two or three overcurrent
devices, respectively.
(B) Power Panelboard Protection. In
addition to the requirements of 408.30,
a power panelboard with supply
conductors that include a neutral, and
having more than 10 percent of its
overcurrent devices protecting branch
circuits rated 30 amperes or less, shall
be protected by an overcurrent
protective device having a rating not
greater than that of the panelboard.
This overcurrent protective device shall Exception No. 3: For existing
be located within or at any point on the panelboards, individual protection shall
Page 191 of 361
Change Description and Impact to
Worker Safety
reformatted to adhere to the new “nonclassified” panelboard requirements.
Sections (A) and (B) were merged into
the general introductory section and
(C), (D), (E) and (F) became new (A),
(B), (C) and (D).
As Safe or Safer.
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supply side of the panelboard.
Exception: This individual protection
shall not be required for a power
panelboard used as service equipment
with multiple disconnecting means in
accordance with 230.71.
408.40 Grounding of Panelboards.
Panelboard cabinets and panelboard
frames, if of metal, shall be in physical
contact with each other and shall be
grounded. Where the panelboard is
used with nonmetallic raceway or cable
or where separate grounding
conductors are provided, a terminal bar
for the grounding conductors shall be
secured inside the cabinet. The
terminal bar shall be bonded to the
cabinet and panelboard frame, if of
metal; otherwise it shall be connected
to the grounding conductor that is run
with the conductors feeding the
panelboard.
Exception: Where an isolated
equipment grounding conductor is
provided as permitted by 250.146(D),
the insulated equipment grounding
conductor that is run with the circuit
2008 NEC
Change Description and Impact to
Worker Safety
not be required for a panelboard used
as service equipment for an individual
residential occupancy.
408.40 Grounding of Panelboards.
Panelboard cabinets and panelboard
frames, if of metal, shall be in physical
contact with each other and shall be
connected to an equipment grounding
conductor. Where the panelboard is
used with nonmetallic raceway or cable
or where separate equipment
grounding conductors are provided, a
terminal bar for the equipment
grounding conductors shall be secured
inside the cabinet. The terminal bar
shall be bonded to the cabinet and
panelboard frame, if of metal;
otherwise it shall be connected to the
equipment grounding conductor that is
run with the conductors feeding the
panelboard.
Exception: Where an isolated
equipment grounding conductor is
provided as permitted by 250.146(D),
the insulated equipment grounding
conductor that is run with the circuit
Page 192 of 361
Inserted “connected to an equipment
grounding conductor” in lieu of just
“grounded” to continue the emphasis
on equipment grounding conductor
function and connections.
May actually improve worker safety.
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conductors shall be permitted to pass
through the panelboard without being
connected to the panelboard’s
equipment grounding terminal bar.
conductors shall be permitted to pass
through the panelboard without being
connected to the panelboard’s
equipment grounding terminal bar.
Grounding conductors shall not be
connected to a terminal bar provided
for grounded conductors (may be a
neutral) unless the bar is identified for
the purpose and is located where
interconnection between equipment
grounding conductors and grounded
circuit conductors is permitted or
required by Article 250.
Equipment grounding conductors shall
not be connected to a terminal bar
provided for grounded conductors or
neutral conductors unless the bar is
identified for the purpose and is
located where interconnection between
equipment grounding conductors and
grounded circuit conductors is
permitted or required by Article 250.
408.54 Maximum Number of
Overcurrent Devices. A panelboard
shall be provided with physical means
to prevent the installation of more
overcurrent devices than that number
for which the panelboard was
designed, rated, and listed.
For the purposes of this section, a 2pole circuit breaker or fusible switch
shall be considered two overcurrent
devices; a 3-pole circuit breaker or
fusible switch shall be considered three
overcurrent devices.
408.55 Wire-Bending Space in
Panelboards. The enclosure for a
panelboard shall have the top and
bottom wire-bending space sized in
408.55 Wire-Bending Space in
Panelboards. The enclosure for a
panelboard shall have the top and
bottom wire-bending space sized in
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Change Description and Impact to
Worker Safety
Section 408.35 was transformed into
the new 408.54 and modified to
remove the specific 42 breaker limit
and rely on the maximum number of
devices for which the panelboard was
designed, rated, and listed.
As Safe or Safer.
Reintroduced the 42 device limit, but
only for the purposes of using an
alternative table to determine wire
bending space.
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accordance with Table 312.6(B) for the
largest conductor entering or leaving
the enclosure. Side wire-bending
space shall be in accordance with
Table 312.6(A) for the largest
conductor to be terminated in that
space.
accordance with Table 312.6(B) for the
largest conductor entering or leaving
the enclosure. Side wire-bending
space shall be in accordance with
Table 312.6(A) for the largest
conductor to be terminated in that
space.
Exception No. 1: Either the top or
bottom wire-bending space shall be
permitted to be sized in accordance
with Table 312.6(A) for a lighting and
appliance branch-circuit panelboard
rated 225 amperes or less.
Exception No. 1: Either the top or
bottom wire-bending space shall be
permitted to be sized in accordance
with Table 312.6(A) for a panelboard
rated 225 amperes or less and
designed to contain not over 42
overcurrent devices. For the purposes
of this exception, a 2-pole or a 3-pole
circuit breaker shall be considered as
two or three overcurrent devices,
respectively.
408.58 Panelboard Marking.
Panelboards shall be durably marked
by the manufacturer with the voltage
and the current rating and the number
of phases for which they are designed
and with the manufacturer’s name or
trademark in such a manner so as to
be visible after installation, without
disturbing the interior parts or wiring.
Article 409
Industrial Control Panels
Industrial Control Panels
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Change Description and Impact to
Worker Safety
As Safe or Safer.
New section created from the original
408.30 second phrase.
As Safe or Safer.
Introduced new definition of control
circuit and reworded the definition of
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409.2 Definitions.
2008 NEC
409.2 Definitions.
Control Circuit. The circuit of a control
apparatus or system that carries the
electric signals directing the
performance of the controller but does
not carry the main power current.
Industrial Control Panel. An assembly
of a systematic and standard
arrangement of two or more
components such as motor controllers,
overload relays, fused disconnect
switches, and circuit breakers and
related control devices such as
pushbutton stations, selector switches,
timers, switches, control relays, and
the like with associated wiring, terminal
blocks, pilot lights, and similar
components. The industrial control
panel does not include the controlled
equipment.
409.21 Overcurrent Protection.
Change Description and Impact to
Worker Safety
industrial control panel.
As Safe or Safer.
Industrial Control Panel. An assembly
of two or more components consisting
of one of the following:
(1) Power circuit components only,
such as motor controllers, overload
relays, fused disconnect switches, and
circuit breakers
(2) Control circuit components only,
such as pushbuttons, pilot lights,
selector switches, timers, switches,
control relays
(3) A combination of power and control
circuit components
These components, with associated
wiring and terminals, are mounted on
or contained within an enclosure or
mounted on a subpanel. The industrial
control panel does not include the
controlled equipment.
409.21 Overcurrent Protection.
Page 195 of 361
Inserted “for each incoming supply
circuit” to reinforce the intent that each
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(B) Location. This protection shall be
provided by either of the following:
(B) Location. This protection shall be
provided for each incoming supply
circuit by either of the following:
409.60 Grounding. Multisection
409.60 Grounding. Multisection
industrial control panels shall be
industrial control panels shall be
bonded together with an equipment
bonded together with an equipment
grounding conductor or an equivalent
grounding conductor or an equivalent
grounding bus sized in accordance
equipment grounding bus sized in
with Table 250.122. Equipment
accordance with Table 250.122.
grounding conductors shall terminate
Equipment grounding conductors shall
on this grounding bus or to a grounding be connected to this equipment
termination point provided in a singlegrounding bus or to an equipment
section industrial control panel.
grounding termination point provided in
a single-section industrial control
panel.
409.104 Wiring Space in Industrial
409.104 Wiring Space in Industrial
Control Panels.
Control Panels.
(B) Wire Bending Space. Wire bending
space for the main supply terminals
shall be in accordance with the
requirements in 312.6. Wire bending
space for other terminals shall be in
accordance with the requirements in
430.10(B). The gutter space shall
comply with 312.8.
(B) Wire Bending Space. Wire bending
space within industrial control panels
for field wiring terminals shall be in
accordance with the requirements in
430.10(B).
409.106 Spacings. Spacings between
live bare metal parts in feeder circuits
shall not be less than specified in
Table 430.97.
Page 196 of 361
Change Description and Impact to
Worker Safety
circuit requires protection.
As Safe or Safer.
Continued emphasis on equipment
grounding conductor connection
versus just grounding.
May actually improve worker safety.
Deleted references to Article 312 and
maintained the Article 430 reference
as that is where the specific
information for wire bending space in
controller enclosures resides.
As Safe or Safer.
New section to address the spacing
between live bare metal parts in
control panels referencing the
controller section in Article 430.
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Exception: Spacings shall be permitted
to be less than those specified in Table
430.97 at circuit breakers and switches
and in listed components installed in
industrial control panels.
409.108 Service-Entrance Equipment. 409.108 Service Equipment. Where
Where used as service equipment,
used as service equipment, each
each industrial control panel shall be of industrial control panel shall be of the
the type that is suitable for use as
type that is suitable for use as service
service equipment.
equipment.
Where a grounded conductor is
Where a grounded conductor is
provided, the industrial control panel
provided, the industrial control panel
shall be provided with a main bonding
shall be provided with a main bonding
jumper, sized in accordance with
jumper, sized in accordance with
250.28(D), for connecting the
250.28(D), for connecting the
grounded conductor, on its supply side, grounded conductor, on its supply side,
to the industrial control panel
to the industrial control panel
equipment ground bus or terminal.
equipment ground bus or equipment
ground terminal.
409.110 Marking. An industrial control
409.110 Marking. An industrial control
panel shall be marked with the
panel shall be marked with the
following information that is plainly
following information that is plainly
visible after installation:
visible after installation:
(1) Manufacturer’s name, trademark, or (1) Manufacturer’s name, trademark, or
other descriptive marking by which the other descriptive marking by which the
organization responsible for the
organization responsible for the
product can be identified.
product can be identified.
(2) Supply voltage, phase, frequency,
and full-load current.
(2) Supply voltage, number of phases,
frequency, and full-load current for
each incoming supply circuit.
Page 197 of 361
Change Description and Impact to
Worker Safety
As Safe or Safer.
Continued emphasis on equipment
grounding conductor connection
versus just grounding.
May actually improve worker safety.
Modified to clarify intent that each
supply circuit is required to be included
in the requirements for marking and to
also identify number of phases. The
exception to short circuit current
markings was added to address the
confusion when no load power circuits
are controlled by the control panel.
Clarified the drawing reference to
reinforce the need for an available
wiring diagram.
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(3) Short-circuit current rating of the
industrial control panel based on one
of the following:
a. Short-circuit current rating of a
listed and labeled assembly
b. Short-circuit current rating
established utilizing an approved
method
2008 NEC
Change Description and Impact to
Worker Safety
As Safe or Safer.
(3) Short-circuit current rating of the
industrial control panel based on one
of the following:
a. Short-circuit current rating of a
listed and labeled assembly
b. Short-circuit current rating
established utilizing an approved
method
Exception to (3): Short-circuit current
rating markings are not required for
industrial control panels containing
only control circuit components.
(4) If the industrial control panel is
intended as service equipment, it shall
be marked to identify it as being
suitable for use as service equipment.
(4) If the industrial control panel is
intended as service equipment, it shall
be marked to identify it as being
suitable for use as service equipment.
(5) Electrical wiring diagram or the
number of the index to the electrical
drawings showing the electrical wiring
diagram.
(5) Electrical wiring diagram or the
identification number of a separate
electrical wiring diagram or a
designation referenced in a separate
wiring diagram.
(6) An enclosure type number shall be
marked on the industrial control panel
enclosure.
(6) An enclosure type number shall be
marked on the industrial control panel
enclosure.
Article 410
Luminaires, Lampholders, and Lamps
Page 198 of 361
Definition of storage space moved
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410.2 Application of Other Articles.
Equipment for use in hazardous
(classified) locations shall conform to
Articles 500 through 517. Lighting
systems operating at 30 volts or less
shall conform to Article 411. Arc lamps
used in theaters shall comply with
520.61, and arc lamps used in
projection machines shall comply with
540.20. Arc lamps used on constantcurrent systems shall comply with the
general requirements of Article 490.
2008 NEC
410.2 Definitions.
Closet Storage Space. The volume
bounded by the sides and back closet
walls and planes extending from the
closet floor vertically to a height of 1.8
m (6 ft) or to the highest clotheshanging rod and parallel to the walls at
a horizontal distance of 600 mm (24
in.) from the sides and back of the
closet walls, respectively, and
continuing vertically to the closet
ceiling parallel to the walls at a
horizontal distance of 300 mm (12 in.)
or the width of the shelf, whichever is
greater; for a closet that permits
access to both sides of a hanging rod,
this space includes the volume below
the highest rod extending 300 mm (12
in.) on either side of the rod on a plane
horizontal to the floor extending the
entire length of the rod. See Figure
410.2.
Lighting Track. A manufactured
assembly designed to support and
energize luminaires that are capable of
being readily repositioned on the track.
Its length can be altered by the
addition or subtraction of sections of
Page 199 of 361
Change Description and Impact to
Worker Safety
from original 410.8 to new 410.2 and
renamed Closet Storage Space to
make the article consistent with the
standard format of x.2 being
designated Definitions in each article.
Figure 410.8 likewise became Figure
410.2.
Definition of Lighting Track relocated
from original 410.100.
Original 410.2 Application of Other
Articles was deleted.
As Safe or Safer.
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Change Description and Impact to
Worker Safety
track.

410.6 Listing Required. All luminaires
and lampholders shall be listed.
New 410.6 to require listing for all
devices covered in the article.
As Safe or Safer.
Moved Inspection requirements from
original 410.16(B) to new 410.8.
II. Luminaire (Fixture) Locations
410.8 Inspection. Luminaires shall be
installed such that the connections
between the luminaire conductors and
the circuit conductors can be inspected
without requiring the disconnection of
any part of the wiring unless the
luminaires are connected by
attachment plugs and receptacles.
II. Luminaire Locations
410.4 Luminaires (Fixtures) in Specific
Locations.
410.10 Luminaires in Specific
Locations.
(D) Bathtub and Shower Areas. No
parts of cord-connected luminaires
(fixtures), chain-, cable-, or cordsuspended-luminaires (fixtures),
lighting track, pendants, or ceilingsuspended (paddle) fans shall be
located within a zone measured 900
mm (3 ft) horizontally and 2.5 m (8 ft)
vertically from the top of the bathtub
rim or shower stall threshold. This zone
is all encompassing and includes the
(D) Bathtub and Shower Areas. No
parts of cord-connected luminaires,
As Safe or Safer.
chain-, cable-, or cord-suspended
luminaires, lighting track, pendants, or
ceiling-suspended (paddle) fans shall
be located within a zone measured 900
mm (3 ft) horizontally and 2.5 m (8 ft)
vertically from the top of the bathtub
rim or shower stall threshold. This zone
is all encompassing and includes the
space directly over the tub or shower
Page 200 of 361
As Safe or Safer.
Original 410.4 became 410.10 and
additional requirements added to
address marking of the devices used
within the defined shower and bathtub
space.
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zone directly over the tub or shower
stall. Luminaires (lighting fixtures)
located in this zone shall be listed for
damp locations, or listed for wet
locations where subject to shower
spray.
2008 NEC
Change Description and Impact to
Worker Safety
stall. Luminaires located within the
actual outside dimension of the bathtub
or shower to a height of 2.5 m (8 ft)
vertically from the top of the bathtub
rim or shower threshold shall be
marked for damp locations, or marked
for wet locations where subject to
shower spray.
IV. Luminaire (Fixture) Supports
IV. Luminaire Supports
410.15 Supports.
410.30 Supports.
(B) Metal or Nonmetallic Poles
Supporting Luminaires (Lighting
Fixtures). Metal or nonmetallic poles
shall be permitted to be used to
support luminaires (lighting fixtures)
and as a raceway to enclose supply
conductors, provided the following
conditions are met:
(1) A pole shall have a handhole not
less than 50 mm × 100 mm (2 in. × 4
in.) with a rain-tight cover to provide
access to the supply terminations
within the pole or pole base.
IV. Luminaire (Fixture) Supports
(B) Metal or Nonmetallic Poles
Supporting Luminaires. Metal or
nonmetallic poles shall be permitted to
be used to support luminaires and as a
raceway to enclose supply conductors,
provided the following conditions are
met:
(1) A pole shall have a handhole not
less than 50 mm × 100 mm (2 in. × 4
in.) with a cover suitable for use in wet
locations to provide access to the
supply terminations within the pole or
pole base.
410.30 Supports.
Page 201 of 361
Will not address changes associated
with “410.16 Luminaires in Clothes
Closets.” As that is determined to be
residential in nature.
Inserted “suitable for use in wet
locations” into original 410.15(B)(1) in
lieu of “rain-tight” to align with listing
language and renumbered
410.30(B)(1).
As Safe or Safer.
Continued emphasis on equipment
grounding conductor connection
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410.15 Supports.
2008 NEC
(B) Metal or Nonmetallic Poles
Supporting Luminaires.
(B) Metal or Nonmetallic Poles
Supporting Luminaires (Lighting
Fixtures).
(3) A metal pole shall be provided with
a grounding terminal as follows:
a. A pole with a handhole shall have
the grounding terminal accessible from
the handhole.
b. A pole with a hinged base shall have
the grounding terminal accessible
within the base.
410.18 Exposed Luminaire (Fixture)
Parts.
(A) Exposed Conductive Parts.
Exposed metal parts shall be grounded
or insulated from ground and other
conducting surfaces or be inaccessible
to unqualified personnel. Lamp tie
wires, mounting screws, clips, and
decorative bands on glass spaced at
least 38 mm (11⁄2 in.) from lamp
terminals shall not be required to be
grounded.
410.18 Exposed Luminaire (Fixture)
Parts.
(B) Made of Insulating Material.
Change Description and Impact to
Worker Safety
versus just grounding.
May actually improve worker safety.
(3) A metal pole shall be provided with
an equipment grounding terminal as
follows:
a. A pole with a handhole shall have
the equipment grounding terminal
accessible from the handhole.
b. A pole with a hinged base shall
have the equipment grounding
terminal accessible within the base.
410.42 Exposed Luminaire.
Continued emphasis on equipment
grounding conductor connection
versus just grounding.
(A) Exposed Conductive Parts.
Exposed metal parts shall be
connected to an equipment grounding
May actually improve worker safety.
conductor or insulated from the
equipment grounding conductor and
other conducting surfaces or be
inaccessible to unqualified personnel.
Lamp tie wires, mounting screws, clips,
and decorative bands on glass spaced
at least 38 mm (11⁄2 in.) from lamp
terminals shall not be required to be
grounded.
410.42 Exposed Luminaire.
Continued emphasis on equipment
grounding conductor connection
(B) Made of Insulating Material.
versus just grounding.
Page 202 of 361
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Luminaires (fixtures) directly wired or
attached to outlets supplied by a wiring
method that does not provide a ready
means for grounding shall be made of
insulating material and shall have no
exposed conductive parts.
410.30 Cord-Connected Lampholders
and Luminaires (Fixtures).
(C) Electric-Discharge Luminaires
(Fixtures).
(1) Cord Connected Installation. A
listed luminaire (fixture) or a listed
assembly shall be permitted to be cord
connected if the following conditions
apply:
(1) The luminaire (fixture) is located
directly below the outlet or busway.
(2) The flexible cord meets all the
following:
a. Is visible for its entire length
outside the luminaire (fixture)
b. Is not subject to strain or
physical damage
c. Is terminated in a groundingtype attachment plug cap or
busway plug, or is a part of a
listed assembly incorporating
a manufactured wiring system
2008 NEC
Change Description and Impact to
Worker Safety
Luminaires directly wired or attached to
outlets supplied by a wiring method
May actually improve worker safety.
that does not provide a ready means
for grounding attachment to an
equipment grounding conductor shall
be made of insulating material and
shall have no exposed conductive
parts.
410.62 Cord-Connected Lampholders
Added “having a maximum 152 mm (6
and Luminaires.
in.) long section of raceway for
attachment to an outlet box above a
(C) Electric-Discharge Luminaires.
suspended ceiling” to limit the long
raceway sections typically used to
(1) Cord-Connected Installation. A
connect to a power source. The power
luminaire or a listed assembly shall be source should be near the luminaire
permitted to be cord connected if the
location.
following conditions apply:
(1) The luminaire is located directly
As Safe or Safer.
below the outlet or busway.
(2) The flexible cord meets all the
following:
a. Is visible for its entire length
outside the luminaire
b. Is not subject to strain or
physical damage
c. Is terminated in a groundingtype attachment plug cap or
busway plug, or is a part of a listed
assembly incorporating a
manufactured wiring system
connector in accordance with
Page 203 of 361
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connector in accordance with
604.6(C), or has a luminaire
(fixture) assembly with a strain
relief and canopy
604.6(C), or has a luminaire
assembly with a strain relief and
canopy having a maximum 152
mm (6 in.) long section of raceway
for attachment to an outlet box
above a suspended ceiling
410.68 Feeder and Branch-Circuit
Conductors and Ballasts. Feeder and
branch-circuit conductors within 75 mm
(3 in.) of a ballast shall have an
insulation temperature rating not lower
than 90°C (194°F) unless supplying a
luminaire marked as suitable for a
different insulation temperature.
410.74 Luminaire Rating.
(A) Marking. All luminaires shall be
marked with the maximum lamp
wattage or electrical rating,
manufacturer’s name, trademark, or
other suitable means of identification.
A luminaire requiring supply wire rated
higher than 60°C (140°F) shall be
marked with the minimum supply wire
temperature rating on the luminaire
and shipping carton or equivalent.
410.33 Branch Circuit Conductors and
Ballasts. Branch circuit conductors
within 75 mm (3 in.) of a ballast shall
have an insulation temperature rating
not lower than 90°C (194°F) unless
supplying a luminaire (fixture) listed
and marked as suitable for a different
insulation temperature.
410.35 Luminaire (Fixture) Rating.
(A) Marking. All luminaires (fixtures)
shall be marked with the maximum
lamp wattage or electrical rating,
manufacturer’s name, trademark, or
other suitable means of identification.
A luminaire (fixture) requiring supply
wire rated higher than 60°C (140°F)
shall be marked in letters not smaller
than 6 mm (1⁄4 in.) high, prominently
displayed on the luminaire (fixture) and
shipping carton or equivalent.
410.45 Tests. All wiring shall be free
from short circuits and grounds and
shall be tested for these defects prior
to being connected to the circuit.
410.85 Tests. All wiring shall be free
from short circuits and ground faults as
defined in 250.2 and shall be tested for
these defects prior to being connected
Page 204 of 361
Change Description and Impact to
Worker Safety
Added “feeder” to assure that feeder
conductors are also protected from
excessive heat if installed near
luminaires.
As Safe or Safer.
Replaced the phrase “in letters not
smaller than 6 mm (1⁄4 in.) high,
prominently displayed on the luminaire
(fixture) and shipping carton or
equivalent” with the phrase “with the
minimum supply wire temperature
rating on the luminaire and shipping
carton or equivalent” to assure that the
required wire temperature rating
actually made it to the luminaire
markings.
As Safe or Safer.
Modified to specifically point to the
defined term “ground faults” versus the
ambiguous term “grounds.”
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XIII. Special Provisions for ElectricDischarge Lighting Systems of 1000
Volts or Less
to the circuit.
XIII. Special Provisions for ElectricDischarge Lighting Systems of 1000
Volts or Less
410.73 General.
410.130 General.
Change Description and Impact to
Worker Safety
As Safe or Safer.
Added new sections to provide the
specific requirements for the location
of the disconnecting means and for
multiwire branch circuit operation.
May actually improve worker safety.
(G) Disconnecting Means.
(G) Disconnecting Means.
(2) Multiwire Branch Circuits. When
connected to multiwire branch circuits,
the disconnecting means shall
simultaneously break all the supply
conductors to the ballast, including the
grounded conductor.
410.81 Control
(3) Location. The disconnecting means
shall be located so as to be accessible
to qualified persons before servicing or
maintaining the ballast. Where the
disconnecting means is external to the
luminaire, it shall be a single device,
and shall be attached to the luminaire
or the luminaire shall be located within
sight of the disconnecting means.
410.141 Control.
(B) Within Sight or Locked Type. The
switch or circuit breaker shall be
located within sight from the luminaires
(fixtures) or lamps, or it shall be
(B) Within Sight or Locked Type. The
switch or circuit breaker shall be
located within sight from the luminaires
or lamps, or it shall be permitted
Page 205 of 361
This change aligns with many other
articles throughout the Code, where
provision for locking the disconnecting
means is specified to be a permanent
part of the disconnecting means.
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permitted elsewhere if it is provided
with a means for locking in the open
position.
XV. Lighting Track
410.101 Installation.
(D) Support. Fittings identified for use
on lighting track shall be designed
specifically for the track on which they
are to be installed. They shall be
securely fastened to the track, shall
maintain polarization and grounding,
and shall be designed to be suspended
directly from the track.
Lighting Systems Operating at 30 Volts
or Less
411.2 Definition.
Lighting Systems Operating at 30 Volts
or Less. A lighting system consisting of
an isolating power supply operating at
30 volts (42.4 volts peak) or less under
2008 NEC
Change Description and Impact to
Worker Safety
elsewhere if it is provided with a means As Safe or Safer.
for locking in the open position. The
provisions for locking or adding a lock
to the disconnecting means must
remain in place at the switch or circuit
breaker whether the lock is installed or
not. Portable means for adding a lock
to the switch or circuit breaker shall not
be permitted.
XV. Lighting Track
Continued emphasis on connection to
the equipment grounding conductor
410.151 Installation.
versus just grounding.
(D) Support. Fittings identified for use
May actually improve worker safety.
on lighting track shall be designed
specifically for the track on which they
are to be installed. They shall be
securely fastened to the track, shall
maintain polarization and connections
to the equipment grounding conductor,
and shall be designed to be suspended
directly from the track.
Article 411
Lighting Systems Operating at 30 Volts Modified to emphasize the rating of the
or Less
output circuits and the entire system
under all load conditions.
411.2 Definition.
Lighting Systems Operating at 30 Volts As Safe or Safer.
or Less. A lighting system consisting of
an isolating power supply, the low
voltage luminaires, and associated
Page 206 of 361
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any load condition, with one or more
secondary circuits, each limited to 25
amperes maximum, supplying
luminaires (lighting fixtures) and
associated equipment identified for the
use.
411.3 Listing Required. Lighting
systems operating at 30 volts or less
shall be listed.
equipment that are all identified for the
use. The output circuits of the power
supply are rated for not more than 25
amperes and operate at 30 volts
(42.4 volts peak) or less under all load
conditions.
411.3 Listing Required. Lighting
systems operating at 30 volts or less
shall comply with 411.3(A) or 411.3(B).
(A) Listed System. Lighting systems
operating at 30 volts or less shall be
listed as a complete system. The
luminaires, power supply, and
luminaire fittings (including the
exposed bare conductors) of an
exposed bare conductor lighting
system shall be listed for the use as
part of the same identified lighting
system.
(B) Assembly of Listed Parts. A lighting
system assembled from the following
listed parts shall be permitted:
(1) Low-voltage luminaires
(2) Low-voltage luminaire power supply
(3) Class 2 power supply
(4) Low-voltage luminaire fittings
(5) Cord (secondary circuit) for which
the luminaires and power supply are
listed for use
Page 207 of 361
Change Description and Impact to
Worker Safety
Modified to add the specific listing
requirements and allowances to
assure proper installations.
As Safe or Safer.
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411.4 Locations Not Permitted.
Lighting systems operating at 30 volts
or less shall not be installed in the
locations described in 411.4(A) and
411.4(B).
(A) Where concealed or extended
through a building wall unless
permitted in (1) or (2):
(1) Installed using any of the wiring
methods specified in Chapter 3
(2) Installed using wiring supplied by a
listed Class 2 power source and
installed in accordance with 725.52
(B) Where installed within 3.0 m (10 ft)
of pools, spas, fountains, or similar
locations, unless permitted by Article
680.
411.5 Secondary Circuits.
2008 NEC
(6) Cable, conductors in conduit, or
other fixed wiring method for the
secondary circuit
The luminaires, power supply, and
luminaire fittings (including the
exposed bare conductors) of an
exposed bare conductor lighting
system shall be listed for use as part of
the same identified lighting system.
411.4 Specific Location Requirements.
(A) Walls, Floors, and Ceilings.
Conductors concealed or extended
through a wall, floor, or ceiling shall be
in accordance with (1) or (2):
(1) Installed using any of the wiring
methods specified in Chapter 3
Change Description and Impact to
Worker Safety
Modified to convert to positive Code
language and detail the requirements
rather than indicate “not permitted” for
the lighting systems and allow
exceptions.
As Safe or Safer.
(2) Installed using wiring supplied by
a listed Class 2 power source and
installed in accordance with 725.130
(B) Pools, Spas, Fountains, and
Similar Locations. Lighting systems
shall be installed not less than 3 m (10
ft) horizontally from the nearest edge of
the water, unless permitted by Article
680.
411.5 Secondary Circuits.
Page 208 of 361
New section to address the complete
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(D) Insulated Conductors. Exposed
insulated secondary circuit conductors
shall be of the type, and installed as,
described in (1), (2), or (3):
Change Description and Impact to
Worker Safety
system – grounding, isolation, bare
conductors AND insulated conductors.
As Safe or Safer.
(1) Class 2 cable supplied by a Class 2
power source and installed in
accordance with Parts I and III of
Article 725.
Appliances
(2) Conductors, cord, or cable of the
listed system and installed not less
than 2.1 m (7 ft) above the finished
floor unless the system is specifically
listed for a lower installation height.
(3) Wiring methods described in
Chapter 3
Article 422
Appliances
422.51 Cord-and-Plug-Connected
Vending Machines. Cord-and-plugconnected vending machines
manufactured or re-manufactured on
or after January 1, 2005, shall include
a ground-fault circuit-interrupter as an
integral part of the attachment plug or
located in the power supply cord within
300 mm (12 in.) of the attachment
plug. Cord-and-plug connected
422.51 Cord-and-Plug-Connected
Vending Machines. Cord-and-plugconnected vending machines
manufactured or re-manufactured on
or after January 1, 2005, shall include
a ground-fault circuit interrupter as an
integral part of the attachment plug or
be located within 300 mm (12 in.) of
the attachment plug. Older vending
machines manufactured or
Page 209 of 361
Clarified the original intent of the
section introduced during the 2005
cycle with respect to the location and
integral plug requirement and to
provide a definition of vending
machine.
May actually increase worker safety.
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vending machines not incorporating
integral GFCI protection shall be
connected to a GFCI protected outlet.
2008 NEC
remanufactured prior to January 1,
2005, shall be connected to a GFCIprotected outlet. For the purpose of
this section, the term vending machine
means any self-service device that
dispenses products or merchandise
without the necessity of replenishing
the device between each vending
operation and is designed to require
insertion of a coin, paper currency,
token, card, key, or receipt of payment
by other means.
422.52 Electric Drinking Fountains.
Electric drinking fountains shall be
protected with ground-fault circuit
interrupter protection.
Change Description and Impact to
Worker Safety
New section added to address
concerns of electrocution via water
fountains.
May actually increase worker safety.
Fixed Electric Space-Heating
Equipment
Article 424
Fixed Electric Space-Heating
Equipment
III. Control and Protection of Fixed
Electric Space-Heating Equipment
III. Control and Protection of Fixed
Electric Space-Heating Equipment
424.19 Disconnecting Means. Means
shall be provided to disconnect the
heater, motor controller(s), and
supplementary overcurrent protective
device(s) of all fixed electric spaceheating equipment from all ungrounded
conductors. Where heating equipment
424.19 Disconnecting Means. Means
shall be provided to simultaneously
disconnect the heater, motor
controller(s), and supplementary
overcurrent protective device(s) of all
fixed electric space-heating equipment
from all ungrounded conductors.
Page 210 of 361
Added disconnecting means rating
requirements as well as locking means
requirements.
May actually improve worker safety.
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is supplied by more than one source,
the disconnecting means shall be
grouped and marked.
2008 NEC
VI. Control and Protection
Where heating equipment is supplied
by more than one source, the
disconnecting means shall be grouped
and marked. The disconnecting means
specified in 424.19(A) and (B) shall
have an ampere rating not less than
125 percent of the total load of the
motors and the heaters. The provision
for locking or adding a lock to the
disconnecting means shall be installed
on or at the switch or circuit breaker
used as the disconnecting means and
shall remain in place with or without
the lock installed.
Article 426
Fixed Outdoor Electric Deicing and
Snow-Melting Equipment
426.44 Grounding. The ferromagnetic
envelope shall be connected to an
equipment grounding conductor at both
ends; and, in addition, it shall be
permitted to be connected to an
equipment grounding conductor at
intermediate points as required by its
design.
The provisions of 250.30 shall not
apply to the installation of skin-effect
heating systems.
VI. Control and Protection
426.50 Disconnecting Means.
426.50 Disconnecting Means.
Fixed Outdoor Electric Deicing and
Snow-Melting Equipment
426.44 Grounding. The ferromagnetic
envelope shall be grounded at both
ends; and, in addition, it shall be
permitted to be grounded at
intermediate points as required by its
design.
The provisions of 250.30 shall not
apply to the installation of skin-effect
heating systems.
Page 211 of 361
Change Description and Impact to
Worker Safety
Continued emphasis on connected to
an equipment grounding conductor
versus grounded.
May actually improve worker safety.
Inserted “simultaneous” to eliminate
bad habit of singly disconnecting each
conductor.
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(A) Disconnection. All fixed outdoor
deicing and snow-melting equipment
shall be provided with a means for
disconnection from all ungrounded
conductors. Where readily accessible
to the user of the equipment, the
branch-circuit switch or circuit breaker
shall be permitted to serve as the
disconnecting means. The
disconnecting means shall be of the
indicating type and be provided with a
positive lockout in the “off” position.
426.52 Overcurrent Protection. Fixed
outdoor electric deicing and snowmelting equipment shall be permitted
to be protected against overcurrent
where supplied by a branch circuit as
specified in 426.4.
Fixed Electric Heating Equipment
for Pipelines and Vessels
427.13 Identification. The presence of
electrically heated pipelines, vessels,
or both, shall be evident by the posting
of appropriate caution signs or
markings at frequent intervals along
the pipeline or vessel.
2008 NEC
Change Description and Impact to
Worker Safety
(A) Disconnection. All fixed outdoor
deicing and snow-melting equipment
May actually improve worker safety.
shall be provided with a means for
simultaneous disconnection from all
ungrounded conductors. Where readily
accessible to the user of the
equipment, the branch-circuit switch or
circuit breaker shall be permitted to
serve as the disconnecting means. The
disconnecting means shall be of the
indicating type and be provided with a
positive lockout in the “off” position.
Deleted 426.52 due to incorporation
into Article 240 requirements.
As Safe or Safer.
Article 427
Fixed Electric Heating Equipment
for Pipelines and Vessels
427.13 Identification. The presence of
electrically heated pipelines, vessels,
or both, shall be evident by the posting
of appropriate caution signs or
markings at intervals not exceeding 6
m (20 ft) along the pipeline or vessel
and on or adjacent to equipment in the
piping system that requires periodic
servicing.
Page 212 of 361
Places specific requirements in the
Code to assure that “frequent intervals”
are implemented consistently.
As Safe or Safer.
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Change Description and Impact to
Worker Safety
Again, simultaneously was interjected
to assure the intent of the section
regarding disconnecting means.
VII. Control and Protection
VII. Control and Protection
427.55 Disconnecting Means.
427.55 Disconnecting Means.
(A) Switch or Circuit Breaker. Means
shall be provided to disconnect all fixed
electric pipeline or vessel heating
equipment from all ungrounded
conductors. The branch-circuit switch
or circuit breaker, where readily
accessible to the user of the
equipment, shall be permitted to serve
as the disconnecting means. The
disconnecting means shall be of the
indicating type and shall be provided
with a positive lockout in the “off”
position.
427.56 Controls.
(A) Switch or Circuit Breaker. Means
shall be provided to simultaneously
disconnect all fixed electric pipeline or
vessel heating equipment from all
ungrounded conductors. The branchcircuit switch or circuit breaker, where
readily accessible to the user of the
equipment, shall be permitted to serve
as the disconnecting means. The
disconnecting means shall be of the
indicating type and shall be provided
with a positive lockout in the “off”
position.
427.56 Controls.
(A) Temperature Control with “Off”
Position. Temperature-controlled
switching devices that indicate an “off”
position and that interrupt line current
shall open all ungrounded conductors
when the control device is in this “off”
position. These devices shall not be
permitted to serve as the disconnecting
means unless provided with a positive
lockout in the “off” position.
427.56 Controls.
(A) Temperature Control with “Off”
Position. Temperature-controlled
switching devices that indicate an “off”
position and that interrupt line current
shall open all ungrounded conductors
when the control device is in this “off”
position. These devices shall not be
As Safe or Safer.
permitted to serve as the disconnecting
means unless capable of being locked
in the open position.
427.56 Controls.
Modified to read “capable of being
locked in the open position” instead of
Page 213 of 361
As Safe or Safer.
Modified to read “capable of being
locked in the open position” instead of
“provided with a positive lockout in the
“off” position” to assure the disconnect
itself, was actually capable of being
locked in the open position versus
“being provided” another means.
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(D) Combined Switching Devices.
Switching devices consisting of
combined temperature-actuated
devices and manually controlled
switches that serve both as the
controllers and the disconnecting
means shall comply with all the
following conditions:
(1) Open all ungrounded conductors
when manually placed in the “off”
position
(2) Be designed so that the circuit
cannot be energized automatically if
the device has been manually placed
in the “off” position
(3) Be provided with a positive lockout
in the “off” position
(D) Combined Switching Devices.
Switching devices consisting of
combined temperature-actuated
devices and manually controlled
switches that serve both as the
controllers and the disconnecting
means shall comply with all the
following conditions:
(1) Open all ungrounded conductors
when manually placed in the “off”
position
(2) Be designed so that the circuit
cannot be energized automatically if
the device has been manually placed
in the “off” position
(3) Be capable of being locked in the
open position
Motors, Motor Circuits, and Controllers
Article 430
Motors, Motor Circuits, and Controllers
430.2 Definitions.
430.2 Definitions.
III. Motor and Branch-Circuit Overload
Valve Actuator Motor (VAM)
Assemblies. A manufactured
assembly, used to operate a valve,
consisting of an actuator motor and
other components such as controllers,
torque switches, limit switches, and
overload protection.
III. Motor and Branch-Circuit Overload
Page 214 of 361
Change Description and Impact to
Worker Safety
“provided with a positive lockout in the
“off” position” to assure the disconnect
itself, was actually capable of being
locked in the open position versus
“being provided” another means.
As Safe or Safer.
Added definition for Valve Actuator
Motors as they have become more and
more widely used in industry.
As Safe or Safer.
The definition of Overload was moved
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Change Description and Impact to
Worker Safety
to Article 100 to be consistent with
NFPA Manual of Style for the NEC to
make definitions that affect more than
one Article available for the entire
document.
Protection
Protection
430.31 General. Part III specifies
overload devices intended to protect
motors, motor-control apparatus, and
motor branch-circuit conductors
against excessive heating due to motor
overloads and failure to start.
Overload in electrical apparatus is an
operating overcurrent that, when it
persists for a sufficient length of time,
would cause damage or dangerous
overheating of the apparatus. It does
not include short circuits or ground
faults.
These provisions shall not be
interpreted as requiring overload
protection where it might introduce
additional or increased hazards, as in
the case of fire pumps.
430.32 Continuous-Duty Motors.
430.31 General. Part III specifies
overload devices intended to protect
motors, motor-control apparatus, and
motor branch-circuit conductors
against excessive heating due to motor As Safe or Safer.
overloads and failure to start.
(C) Selection of Overload Relay.
Where the sensing element or setting
of the overload relay selected in
accordance with 430.32(A)(1) and
430.32(B)(1) is not sufficient to start
the motor or to carry the load, higher
size sensing elements or incremental
settings shall be permitted to be used,
provided the trip current of the
(C) Selection of Overload Device.
Where the sensing element or setting
or sizing of the overload device
selected in accordance with
430.32(A)(1) and 430.32(B)(1) is not
sufficient to start the motor or to carry
the load, higher size sensing elements
or incremental settings or sizing shall
be permitted to be used, provided the

These provisions shall not be
interpreted as requiring overload
protection where it might introduce
additional or increased hazards, as in
the case of fire pumps.
430.32 Continuous-Duty Motors.
Page 215 of 361
Use of the term “relay” limited the
types of overload devices that could be
used for overload selection and was
replaced with the generic term “device”
and words inserted to assure that all
listed types of overload devices could
be applied.
As Safe or Safer.
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trip current of the overload device does
not exceed the following percentage of
motor nameplate full-load current
rating:
430.73 Mechanical Protection of
430.73 Protection of Conductor from
Conductor. Where damage to a motor
Physical Damage. Where damage to a
control circuit would constitute a
motor control circuit would constitute a
hazard, all conductors of such a
hazard, all conductors of such a
remote motor control circuit that are
remote motor control circuit that are
outside the control device itself shall be outside the control device itself shall be
installed in a raceway or be otherwise
installed in a raceway or be otherwise
suitably protected from physical
suitably protected from physical
damage.
damage.
Where one side of the motor control
circuit is grounded, the motor control
430.74 Electrical Arrangement of
circuit shall be arranged so that an
Control Circuits. Where one side of the
accidental ground in the control circuit
motor control circuit is grounded, the
remote from the motor controller will
motor control circuit shall be arranged
(1) not start the motor and (2) not
so that an accidental ground in the
bypass manually operated shutdown
control circuit remote from the motor
devices or automatic safety shutdown
controller will (1) not start the motor
devices.
and (2) not bypass manually operated
shutdown devices or automatic safety
shutdown devices.
VII. Motor Controllers
VII. Motor Controllers
Change Description and Impact to
Worker Safety
overload relay does not exceed the
following percentage of motor
nameplate full-load current rating:
430.81 General. Part VII is intended to
require suitable controllers for all
motors.
(A) Stationary Motor of 1⁄8 Horsepower
or Less. For a stationary motor rated at
430.81 General. Part VII is intended to
require suitable controllers for all
motors.
(A) Stationary Motor of 1⁄8 Horsepower
or Less. For a stationary motor rated at
Page 216 of 361
Old section 430.73 was split into
430.73 and 430.74 and old 430.74 was
renumbered 430.75. The change was
made to accentuate the new headings
of “Protection of Conductor from
Physical Damage” and “Electrical
Arrangement of Control Circuits” which
may have hidden by the old heading
“Mechanical Protection of Conductor.”
As Safe or Safer.
The term “disconnecting means”
replaced “protective device” to
emphasize that it must actually be a
disconnecting means, not just a
protective device, since some
protective devices do not qualify as a
disconnecting means.
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Change Description and Impact to
Worker Safety
1⁄8 hp or less that is normally left
running and is constructed so that it
cannot be damaged by overload or
failure to start, such as clock motors
and the like, the branch-circuit
protective device shall be permitted to
serve as the controller.
430.87 Number of Motors Served by
Each Controller. Each motor shall be
provided with an individual controller.
1⁄8 hp or less that is normally left
running and is constructed so that it
cannot be damaged by overload or
failure to start, such as clock motors
and the like, the branch-circuit
disconnecting means shall be
permitted to serve as the controller.
430.87 Number of Motors Served by
Each Controller. Each motor shall be
provided with an individual controller.
Exception: For motors rated 600 volts
or less, a single controller rated at not
less than the equivalent horsepower,
as determined in accordance with
430.110(C)(1), of all the motors in the
group shall be permitted to serve the
group under any of the following
conditions:
(a) Where a number of motors drive
several parts of a single machine or
piece of apparatus, such as metal and
woodworking machines, cranes, hoists,
and similar apparatus
(b) Where a group of motors is under
the protection of one overcurrent
device as permitted in 430.53(A)
(c) Where a group of motors is located
in a single room within sight from the
controller location
Exception No. 1: For motors rated 600
volts or less, a single controller rated at As Safe or Safer.
not less than the equivalent
horsepower, as determined in
accordance with 430.110(C)(1), of
all the motors in the group shall be
permitted to serve the group under any
of the following conditions:
(a) Where a number of motors drive
several parts of a single machine or
piece of apparatus, such as metal
and woodworking machines, cranes,
hoists, and similar apparatus
(b) Where a group of motors is
under the protection of one
overcurrent device as permitted in
430.53(A)
(c) Where a group of motors is
located in a single room within sight
from the controller location
Page 217 of 361
As Safe or Safer.
Added Exception No. 2 to address the
change made in 430.81(A) regarding
the branch-circuit disconnecting means
used as the controller.
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Change Description and Impact to
Worker Safety
Exception No. 2: A branch-circuit
disconnecting means serving as the
controller as allowed in 430.81(A) shall
be permitted to serve more than one
motor.
430.91 Motor Controller Enclosure
Types. Table 430.91 provides the
basis for selecting enclosures for use
in specific locations other than
hazardous (classified) locations.
The enclosures are not intended to
protect against conditions such as
condensation, icing, corrosion, or
contamination that may occur within
the enclosure or enter via the conduit
or unsealed openings. These internal
conditions shall require special
consideration by the installer and user.
430.96 Grounding. Multisection motor
control centers shall be bonded
together with an equipment grounding
conductor or an equivalent grounding
bus sized in accordance with Table
250.122. Equipment grounding
conductors shall terminate on this
grounding bus or to a grounding
termination point provided in a singlesection motor control center.
430.102 Location.
This information was moved to new
Section 110.20 as an effort to have
enclosure types apply to more than
motor controllers.
As Safe or Safer.
430.96 Grounding. Multisection motor
control centers shall be connected
together with an equipment grounding
conductor or an equivalent equipment
grounding bus sized in accordance
with Table 250.122. Equipment
grounding conductors shall be
connected to this equipment grounding
bus or to a grounding termination point
provided in a single-section motor
control center.
430.102 Location.
Page 218 of 361
Continued emphasis on “connected” to
an equipment grounding conductor.
As Safe or Safer.
Added new exception to cover
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(A) Controller.
2008 NEC
(A) Controller.
Exception No. 3: The disconnecting
means shall not be required to be in
sight from valve actuator motor (VAM)
assemblies containing the controller
where such a location introduces
additional or increased hazards to
persons or property and conditions (a)
and (b) are met.
(a) The valve actuator motor assembly
is marked with a warning label giving
the location of the disconnecting
means.
(b) The provision for locking or adding
a lock to the disconnecting means shall
be installed on or at the switch or
circuit breaker used as the
disconnecting means and shall remain
in place with or without the lock
installed.
430.102 Location.
430.102 Location.
(B) Motor. A disconnecting means shall (B) Motor. A disconnecting means shall
be located in sight from the motor
be provided for a motor in accordance
location and the driven machinery
with (B)(1) or (B)(2).
location.
(1) Separate Motor Disconnect. A
disconnecting means for the motor
shall be located in sight from the motor
location and the driven machinery
location.
(2) Controller Disconnect. The
Page 219 of 361
Change Description and Impact to
Worker Safety
disconnecting means for valve actuator
motor (VAM) assemblies.
As Safe or Safer.
Clarified that a second disconnecting
means is not required where the
controller disconnecting means is
located within sight of the motor and
driven machinery.
As Safe or Safer.
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controller disconnecting means
required in accordance with
430.102(A) shall be permitted to serve
as the disconnecting means for the
motor if it is in sight from the motor
location and the driven machinery
location.
430.103 Operation. The disconnecting 430.103 Operation. The disconnecting
means shall open all ungrounded
means shall open all ungrounded
supply conductors and shall be
supply conductors and shall be
designed so that no pole can be
designed so that no pole can be
operated independently. The
operated independently. The
disconnecting means shall be
disconnecting means shall be
permitted in the same enclosure with
permitted in the same enclosure with
the controller.
the controller. The disconnecting
means shall be designed so that it
cannot be closed automatically.
430.108 Every Disconnecting Means.
430.108 Every Disconnecting Means.
Every disconnecting means in the
Every disconnecting means in the
motor circuit between the point of
motor circuit between the point of
attachment to the feeder and the point attachment to the feeder or branch
of connection to the motor shall comply circuit and the point of connection to
with the requirements of 430.109 and
the motor shall comply with the
430.110.
requirements of 430.109 and 430.110.
430.110 Ampere Rating and
430.110 Ampere Rating and
Interrupting Capacity.
Interrupting Capacity.
(C) For Combination Loads.
Change Description and Impact to
Worker Safety
Added provision prohibiting automatic
closure of a motor disconnecting
means.
As Safe or Safer.
Revised to recognize there may be
more than one disconnecting means in
a motor branch circuit.
As Safe or Safer.
Added a requirement to use the largest
value when comparing the full-load
current and locked-rotor current tables.
(C) For Combination Loads.
As Safe or Safer.
(1) Horsepower Rating.
(1) Horsepower Rating.
Page 220 of 361
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430.126 Motor Overtemperature
Protection.
(A) General. Adjustable speed drive
systems shall protect against motor
overtemperature conditions.
Overtemperature protection is in
addition to the conductor protection
required in 430.32. Protection shall be
provided by one of the following
means.
2008 NEC
….In cases where different current
ratings are obtained when applying
these tables, the largest value obtained
shall be used.
430.126 Motor Overtemperature
Protection.
(A) General. Adjustable speed drive
systems shall protect against motor
overtemperature conditions where the
motor is not rated to operate at the
nameplate rated current over the
speed range required by the
application. This protection shall be
provided in addition to the conductor
protection required in 430.32.
Protection shall be provided by one of
the following means.
(1) Motor thermal protector in
accordance with 430.32
(1) Motor thermal protector in
accordance with 430.32
(2) Adjustable speed drive controller
with load and speed sensitive overload
protection and thermal memory
retention upon shutdown or power loss
(2) Adjustable speed drive system with
load and speed sensitive overload
protection and thermal memory
retention upon shutdown or power loss
(3) Overtemperature protection relay
Exception to (2): Thermal memory
retention upon shutdown or power loss
is not required for continuous duty
loads.
(3) Overtemperature protection relay
Page 221 of 361
Change Description and Impact to
Worker Safety
Clarified the conditions where motor
overtemperature protection is required.
Added exception under which thermal
memory retention is not required.
As Safe or Safer.
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utilizing thermal sensors embedded in
the motor and meeting the
requirements of 430.32(A)(2) or (B)(2)
utilizing thermal sensors embedded in
the motor and meeting the
requirements of 430.32(A)(2) or (B)(2)
(4) Thermal sensor embedded in the
motor that is received and acted upon
by an adjustable speed drive
(4) Thermal sensor embedded in the
motor whose communications are
received and acted upon by an
adjustable speed drive system
430.126 Motor Overtemperature
Protection.
430.126 Motor Overtemperature
Protection.
(B) Motors with Cooling Systems.
Motors that utilize external forced air or
liquid cooling systems shall be
provided with protection that shall be
continuously enabled or enabled
automatically if the cooling system
fails.

(C) Multiple Motor Applications. For
multiple motor applications, individual
motor overtemperature protection shall
be provided.
430.227 Disconnecting Means. The
controller disconnecting means shall
be capable of being locked in the open
position.
(B) Multiple Motor Applications. For
multiple motor applications, individual
motor overtemperature protection shall
be provided as required in 430.126(A).
430.227 Disconnecting Means. The
controller disconnecting means shall
be capable of being locked in the open
position. The provision for locking or
adding a lock to the disconnecting
means shall be installed on or at the
switch or circuit breaker used as the
disconnecting means and shall remain
Change Description and Impact to
Worker Safety
Deleted reference to motors with
cooling systems and provided specific
direction for multiple motor
applications.
As Safe or Safer.
Page 222 of 361
This change aligns with many other
articles throughout the Code, where
provision for locking the disconnecting
means is specified to be a permanent
part of the disconnecting means.
As Safe or Safer.
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in place with or without the lock
installed.
430.243 Portable Motors. The frames
430.243 Portable Motors. The frames
of portable motors that operate at over of portable motors that operate over
150 volts to ground shall be guarded or 150 volts to ground shall be guarded or
grounded.
grounded.
Change Description and Impact to
Worker Safety
The two exceptions have been added
to align the section with the
requirements for portable motors in
Article 250.
Exception No. 1: Listed motor-operated As Safe or Safer.
tools, listed motor-operated
appliances, and listed motor-operated
equipment shall not be required to be
grounded where protected by a system
of double insulation or its equivalent.
Double-insulated equipment shall be
distinctively marked.
430.244 Controllers. Controller
enclosures shall be grounded
regardless of voltage. Controller
enclosures shall have means for
attachment of an equipment grounding
conductor termination in accordance
with 250.8.
Exception No. 2: Listed motor-operated
tools, listed motor-operated
appliances, and listed motor-operated
equipment connected by a cord and
attachment plug, other than those
required to be grounded in accordance
with 250.114.
430.244 Controllers. Controller
Continued emphasis on “connected” to
enclosures shall be connected to the
an equipment grounding conductor.
equipment grounding conductor
regardless of voltage. Controller
As Safe or Safer.
enclosures shall have means for
attachment of an equipment grounding
conductor termination in accordance
with 250.8.
Page 223 of 361
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430.245 Method of Grounding. Where
required, grounding shall be done in
the manner specified in Part VI of
Article 250.
Air-Conditioning and Refrigerating
Equipment
440.14 Location. Disconnecting means
shall be located within sight from and
readily accessible from the airconditioning or refrigerating equipment.
The disconnecting means shall be
permitted to be installed on or within
the air-conditioning or refrigerating
equipment.
The disconnecting means shall not be
located on panels that are designed to
allow access to the air-conditioning or
refrigeration equipment.
440.14 Location.
Exception No. 1…..The provision for
locking or adding a lock to the
disconnecting means shall be
permanently installed on or at the
switch or circuit breaker used as the
disconnecting means.
440.53 Overload Relays. Overload
relays and other devices for motor
2008 NEC
430.245 Method of Grounding.
Connection to the equipment
grounding conductor shall be done in
the manner specified in Part VI of
Article 250.
Article 440
Air-Conditioning and Refrigerating
Equipment
440.14 Location. Disconnecting means
shall be located within sight from and
readily accessible from the airconditioning or refrigerating equipment.
The disconnecting means shall be
permitted to be installed on or within
the air-conditioning or refrigerating
equipment.
The disconnecting means shall not be
located on panels that are designed to
allow access to the air-conditioning or
refrigeration equipment or to obscure
the equipment nameplate(s).
440.14 Location.
Exception No. 1…..The provision for
locking or adding a lock to the
disconnecting means shall be installed
on or at the switch or circuit breaker
and shall remain in place with or
without the lock installed.
440.53 Overload Relays. Overload
relays and other devices for motor
Page 224 of 361
Change Description and Impact to
Worker Safety
Continued emphasis on “connected” to
an equipment grounding conductor.
As Safe or Safer.
Revised to prohibit disconnecting
means from obscuring equipment
nameplate.
As Safe or Safer.
Clarified the type of locking provision
that has to be provided as part of the
installed equipment.
As Safe or Safer.
Revised to require that overload relays
or other devices be identified for group
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overload protection that are not
capable of opening short circuits shall
be protected by fuses or inverse time
circuit breakers with ratings or settings
in accordance with Part III unless
approved for group installation or for
part-winding motors and marked to
indicate the maximum size of fuse or
inverse time circuit breaker by which
they shall be protected.
440.54 Motor-Compressors and
Equipment on 15- or 20- Ampere
Branch Circuits — Not Cord-andAttachment- Plug-Connected.
(A) Overload Protection. The motorcompressor shall be provided with
overload protection selected as
specified in 440.52(A). Both the
controller and motor overload
protective device shall be approved for
installation with the short-circuit and
ground-fault protective device for the
branch circuit to which the equipment
is connected.
overload protection that are not
capable of opening short circuits shall
be protected by fuses or inverse time
circuit breakers with ratings or settings
in accordance with Part III unless
identified for group installation or for
part-winding motors and marked to
indicate the maximum size of fuse or
inverse time circuit breaker by which
they shall be protected.
440.54 Motor-Compressors and
Equipment on 15- or 20-Ampere
Branch Circuits — Not Cord-andAttachment-Plug-Connected.
440.55 Cord-and-Attachment-PlugConnected Motor-Compressors and
Equipment on 15- or 20-Ampere
Branch Circuits.
(A) Overload Protection. The motorcompressor shall be provided with
overload protection selected as
specified in 440.52(A). Both the
controller and motor overload
protective device shall be identified for
installation with the short-circuit and
ground-fault protective device for the
branch circuit to which the equipment
is connected.
440.55 Cord-and-Attachment-PlugConnected Motor-Compressors and
Equipment on 15- or 20-Ampere
Branch Circuits.
(A) Overload Protection. The motor-
(A) Overload Protection. The motor-
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Change Description and Impact to
Worker Safety
installations.
As Safe or Safer.
Revised to require the controller and
the overload protective device to be
identified for installation with the
branch-circuit short-circuit and groundfault protective device.
As Safe or Safer.
Revised to require the controller and
the overload protective device to be
identified for installation with the
branch-circuit short-circuit and groundfault protective device.
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compressor shall be provided with
overload protection as specified in
440.52(A). Both the controller and the
motor overload protective device shall
be approved for installation with the
short-circuit and ground-fault protective
device for the branch circuit to which
the equipment is connected.
440.61 Grounding. Room air
conditioners shall be grounded in
accordance with 250.110, 250.112,
and 250.114.
Generators
compressor shall be provided with
overload protection as specified in
440.52(A). Both the controller and the
motor overload protective device shall
be identified for installation with the
short-circuit and ground-fault protective
device for the branch circuit to which
the equipment is connected.
440.61 Grounding. The enclosures of
room air conditioners shall be
connected to the equipment grounding
conductor in accordance with 250.110,
250.112, and 250.114.
Article 445
Generators
445.13 Ampacity of Conductors.
…Conductors that must carry groundfault currents shall not be smaller than
required by 250.24(C). ………..
445.13 Ampacity of Conductors.
…Conductors that must carry groundfault currents shall not be smaller than
required by 250.30(A). ………….
445.18 Disconnecting Means Required
for Generators. Generators shall be
equipped with disconnect(s) by means
of which the generator and all
protective devices and control
apparatus are able to be disconnected
entirely from the circuits supplied by
the generator except where both of the
following conditions apply:
(1) The driving means for the generator
445.18 Disconnecting Means Required
for Generators. Generators shall be
equipped with disconnect(s), lockable
in the open position, by means of
which the generator and all protective
devices and control apparatus are able
to be disconnected entirely from the
circuits supplied by the generator
except where both of the following
conditions apply:
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Change Description and Impact to
Worker Safety
As Safe or Safer.
Continued emphasis on “connected” to
an equipment grounding conductor.
As Safe or Safer.
Revised to require sizing generator
conductors that carry ground-fault
current by 250.30(A) instead of
250.24(C).
As Safe or Safer.
Revised to require the disconnecting
means be lockable in the open
position.
As Safe or Safer.
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can be readily shut down.
(2) The generator is not arranged to
operate in parallel with another
generator or other source of voltage.
2008 NEC
Transformers and Transformer Vaults
(Including Secondary Ties)
(1) The driving means for the generator
can be readily shut down.
(2) The generator is not arranged to
operate in parallel with another
generator or other source of voltage.
445.19 Generators Supplying Multiple
Loads. A single generator supplying
more than one load, or multiple
generators operating in parallel, shall
be permitted to supply either of the
following:
(1) A vertical switchboard with
separate sections
(2) Individual enclosures with
overcurrent protection tapped from a
single feeder for load separation and
distribution.
Article 450
Transformers and Transformer Vaults
(Including Secondary Ties)
450.5 Grounding Autotransformers
450.5 Grounding Autotransformers
(B) Ground Reference for Fault
Protection Devices. A grounding
autotransformer used to make
available a specified magnitude of
ground-fault current for operation of a
ground-responsive protective device
on a 3-phase, 3-wire ungrounded
system shall conform to 450.5(B)(1)
(B) Ground Reference for Fault
Protection Devices. A grounding
autotransformer used to make
available a specified magnitude of
ground-fault current for operation of a
ground-responsive protective device
on a 3-phase, 3-wire ungrounded
system shall conform to 450.5(B)(1)
Page 227 of 361
Change Description and Impact to
Worker Safety
Added section covering the type of
distribution equipment that can be
used with a generator(s) that supplies
multiple loads.
As Safe or Safer.
Revised to include provisions on
overcurrent protection of grounding
autotransformers used in highimpedance grounded neutral systems.
As Safe or Safer.
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and (B)(2).
and (B)(2).
(2) Overcurrent Protection. An
overcurrent protective device of
adequate short-circuit rating that will
open simultaneously all ungrounded
conductors when it operates shall be
applied in the grounding
autotransformer branch circuit and
shall be rated or set at a current not
exceeding 125 percent of the
autotransformer continuous per-phase
current rating or 42 percent of the
continuous-current rating of any series
connected devices in the
autotransformer neutral connection.
Delayed tripping for temporary
overcurrents to permit the proper
operation of ground-responsive tripping
devices on the main system shall be
permitted but shall not exceed values
that would be more than the short-time
current rating of the grounding
autotransformer or any series
connected devices in the neutral
connection thereto.
(2) Overcurrent Protection. Overcurrent
protection shall comply with (a) and
(b).
(a) Operation and Interrupting Rating.
An overcurrent protective device
having an interrupting rating in
compliance with 110.9 and that will
open simultaneously all ungrounded
conductors when it operates shall be
applied in the grounding
autotransformer branch circuit.
(b) Ampere Rating. The overcurrent
protection shall be rated or set at a
current not exceeding 125 percent of
the autotransformer continuous perphase current rating or 42 percent of
the continuous-current rating of any
series-connected devices in the
autotransformer neutral connection.
Delayed tripping for temporary
overcurrents to permit the proper
operation of ground-responsive tripping
devices on the main system shall be
permitted but shall not exceed values
that would be more than the short-time
current rating of the grounding
autotransformer or any series
connected devices in the neutral
connection thereto.
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Change Description and Impact to
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450.10 Grounding. Exposed non–
current-carrying metal parts of
transformer installations, including
fences, guards, and so forth, shall be
grounded where required under the
conditions and in the manner specified
for electric equipment and other
exposed metal parts in Article 250.
Phase Converters
455.3 Other Articles. All applicable
requirements of this Code shall apply
to phase converters except as
amended by this article.
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Exception: For high-impedance
grounded systems covered in 250.36,
where the maximum ground-fault
current is designed to be not more than
10 amperes, and where the grounding
autotransformer and the grounding
impedance are rated for continuous
duty, an overcurrent device rated not
more than 20 amperes that will
simultaneously open all ungrounded
conductors shall be permitted to be
installed on the line side of the
grounding autotransformer.
450.10 Grounding. Where grounded,
exposed non–current-carrying metal
parts of transformer installations,
including fences, guards, and so forth,
shall be grounded and bonded under
the conditions and in the manner
specified for electrical equipment and
other exposed metal parts in Parts V,
VI, and VII of Article 250.
Article 455
Phase Converters
455.3 Other Articles. Phase converters
shall comply with this article and with
the applicable provisions of other
articles of this Code.
Article 460
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Change Description and Impact to
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Modified to provide specific reference
for the requirements for grounding and
bonding of exposed non-current
carrying metal parts.
As Safe or Safer.
Converted to positive Code text to
indicate that this article governs phase
converters and that other articles of the
Code may apply as well.
No negative imapct.
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Capacitors
Capacitors
460.10 Grounding. Capacitor cases
shall be grounded in accordance with
Article 250.
460.27 Grounding. Capacitor neutrals
and cases, if grounded, shall be
grounded in accordance with Article
250.
460.10 Grounding. Capacitor cases
shall be connected to the equipment
grounding conductor.
460.27 Grounding. Capacitor cases
shall be connected to the equipment
grounding conductor. If the capacitor
neutral point is connected to a
grounding electrode conductor, the
connection shall be made in
accordance with Part III of Article 250.
Exception: Where the capacitor units
are supported on a structure that is
designed to operate at other than
ground potential.
Resistors and Reactors
Exception: Capacitor cases shall not
be connected to the equipment
grounding conductor where the
capacitor units are supported on a
structure designed to operate at other
than ground potential.
Article 470
Resistors and Reactors
470.19 Grounding. Resistor and
reactor cases or enclosures shall be
grounded in accordance with Article
250.
470.19 Grounding. Resistor and
reactor cases or enclosures shall be
connected to the equipment grounding
conductor.
Exception: Resistor or reactor cases or
enclosures supported on a structure
designed to operate at other than
ground potential shall not be grounded.
Exception: Resistor or reactor cases or
enclosures supported on a structure
designed to operate at other than
ground potential shall not be
Page 230 of 361
Change Description and Impact to
Worker Safety
Continued emphasis on “connected” to
an equipment grounding conductor.
As Safe or Safer.
Revised to describe more specifically
the grounding component and function.
As Safe or Safer.
Continued emphasis on “connected” to
an equipment grounding conductor.
As Safe or Safer.
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Storage Batteries
480.3 Wiring and Equipment Supplied
from Batteries. Wiring and equipment
supplied from storage batteries shall
be subject to the requirements of this
Code applying to wiring and equipment
operating at the same voltage, unless
otherwise permitted by 480.4.
Equipment, Over 600 Volts, Nominal
490.36 Grounding. Frames of
switchgear and control assemblies
shall be grounded.
490.37 Grounding of Devices. Devices
with metal cases or frames, or both,
such as instruments, relays, meters,
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connected to the equipment grounding
conductor.
Article 480
Storage Batteries
480.3 Wiring and Equipment Supplied
from Batteries. Wiring and equipment
supplied from storage batteries shall
be subject to the applicable provisions
of this Code applying to wiring and
equipment operating at the same
voltage, unless otherwise permitted by
480.4.
480.5 Disconnecting Means. A
disconnecting means shall be provided
for all ungrounded conductors derived
from a stationary battery system over
30 volts. A disconnecting means shall
be readily accessible and located
within sight of the battery system.
Article 490
Equipment, Over 600 Volts, Nominal
490.36 Grounding. Frames of
switchgear and control assemblies
shall be connected to an equipment
grounding conductor or, where
permitted, the grounded conductor.
490.37 Grounding of Devices. The
metal cases or frames, or both, such
as instruments, relays, meters, and
Page 231 of 361
Change Description and Impact to
Worker Safety
Refines the requirements to applicable
provisions of the Code pertaining to
batteries.
As Safe or Safer.
New section providing the
requirements for a disconnecting
means for battery systems over 30
volts.
As Safe or Safer.
Continued emphasis on “connected” to
an equipment grounding conductor.
As Safe or Safer.
Continued emphasis on “connected” to
an equipment grounding conductor.
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and instrument and control
transformers, located in or on
switchgear or control, shall have the
frame or case grounded.
490.44 Fused Interrupter Switches.
(C) Switching Mechanism. The
switching mechanism shall be
arranged to be operated from a
location outside the enclosure where
the operator is not exposed to
energized parts and shall be arranged
to open all ungrounded conductors of
the circuit simultaneously with one
operation. Switches shall be capable of
being locked in the open position.
490.55 Power Cable Connections to
Mobile Machines. A metallic enclosure
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instrument and control transformers,
located in or on switchgear or control,
shall be connected to an equipment
grounding conductor or, where
permitted, the grounded conductor.
490.44 Fused Interrupter Switches.
(C) Switching Mechanism. The
switching mechanism shall be
arranged to be operated from a
location outside the enclosure where
the operator is not exposed to
energized parts and shall be arranged
to open all ungrounded conductors of
the circuit simultaneously with one
operation. Switches shall be capable of
being locked in the open position. The
provisions for locking shall remain in
place with or without the lock installed.
490.46 Circuit Breaker Locking. Circuit
breakers shall be capable of being
locked in the open position or, if they
are installed in a drawout mechanism,
that mechanism shall be capable of
being locked in such a position that the
mechanism cannot be moved into the
connected position. In either case, the
provision for locking shall remain in
place with or without the lock.
490.55 Power Cable Connections to
Mobile Machines. A metallic enclosure
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Change Description and Impact to
Worker Safety
As Safe or Safer.
Added requirement for the type of
locking provision that has to be
provided as part of the installed
equipment.
As Safe or Safer.
490.46: Added requirement for locking
circuit breakers, including the drawout
type, in the open position and
provisions covering the type of locking
provision that has to be provided as
part of the installed equipment.
Continued emphasis on “connected” to
an equipment grounding conductor.
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shall be provided on the mobile
machine for enclosing the terminals of
the power cable. The enclosure shall
include provisions for a solid
connection for the ground wire(s)
terminal to effectively ground the
machine frame. Ungrounded
conductors shall be attached to
insulators or be terminated in approved
high-voltage cable couplers (which
include ground wire connectors) of
proper voltage and ampere rating.
490.72 Branch-Circuit Requirements.
(D) Ground Current Detection. Means
shall be provided for detection of the
sum of the neutral and ground currents
and shall trip the circuit-interrupting
device if the sum of those currents
exceeds the greater of 5 amperes or
71⁄2 percent of the boiler full-load
current for 10 seconds or exceeds an
instantaneous value of 25 percent of
the boiler full-load current.
Hazardous (Classified) Locations,
Classes I, II, and III, Divisions 1 and 2
500.1 Scope — Articles 500 Through
504. Articles 500 through 504 cover
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Change Description and Impact to
Worker Safety
shall be provided on the mobile
machine for enclosing the terminals of As Safe or Safer.
the power cable. The enclosure shall
include terminal connections to the
machine frame for the equipment
grounding conductor. Ungrounded
conductors shall be attached to
insulators or be terminated in approved
high-voltage cable couplers (which
include equipment grounding
conductor connectors) of proper
voltage and ampere rating.
490.72 Branch-Circuit Requirements.
Continued emphasis on an equipment
grounding conductor versus just
(D) Ground Current Detection. Means
ground.
shall be provided for detection of the
sum of the neutral conductor and
As Safe or Safer.
equipment grounding conductor
currents and shall trip the circuitinterrupting device if the sum of those
currents exceeds the greater of 5
amperes or 71⁄2 percent of the boiler
full-load current for 10 seconds or
exceeds an instantaneous value of 25
percent of the boiler full-load current.
Article 500
Hazardous (Classified) Locations,
Revised scope and other sections to
Classes I, II, and III, Divisions 1 and 2
include ‘‘combustible liquid–produced
vapors’’ as affecting area classification,
500.1 Scope — Articles 500 Through
and replaced ‘‘ignitible fibers or flyings’’
504. Articles 500 through 504 cover
with ‘‘ignitible fibers/flyings’’ in the
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the requirements for electrical and
electronic equipment and wiring for all
voltages in Class I, Divisions 1 and 2;
Class II, Divisions 1 and 2; and Class
III, Divisions 1 and 2 locations where
fire or explosion hazards may exist due
to flammable gases or vapors,
flammable liquids, combustible dust, or
ignitible fibers or flyings.
500.5 Classifications of Locations.
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Change Description and Impact to
Worker Safety
scope and other sections.
the requirements for electrical and
electronic equipment and wiring for all
voltages in Class I, Divisions 1 and 2;
As Safe or Safer.
Class II, Divisions 1 and 2; and Class
III, Divisions 1 and 2 locations where
fire or explosion hazards may exist due
to flammable gases, flammable liquid–
produced vapors, combustible liquid–
produced vapors, combustible dusts,
or ignitible fibers/flyings.
500.5 Classifications of Locations.
Revised several sections to include
‘‘combustible liquid–produced vapors’’
as affecting area classification, and
replaced ‘‘ignitible fibers or flyings’’
with ‘‘ignitible fibers/flyings’’.
(K) Combustible Gas Detection
System.
(1) Inadequate Ventilation.
(2) Interior of a Building.
(3) Interior of a Control Panel.
As Safe or Safer.
Added listing requirements in (K)(1)
through (K)(3) for specific applications
of combustible gas detection
equipment with a statement similar to:
“Combustible gas detection equipment
shall be listed for Class I, Division 1 or
Class I, Division 2, for the appropriate
material group, and for the detection of
the specific gas or vapor to be
encountered.”
500.8 Equipment.
As Safe or Safer.
New section extracted from original
(A)(1) was inserted to emphasize the
500.7 Protection Techniques.
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500.8 Equipment.
(A) Suitability. Suitability of identified
equipment shall be determined by one
of the following:
(1) Equipment listing or labeling
(2) Evidence of equipment evaluation
from a qualified testing laboratory or
inspection agency concerned with
product evaluation
(3) Evidence acceptable to the
authority having jurisdiction such as a
manufacturer’s self-evaluation or an
owner’s engineering judgment.
500.8 Equipment.
(A) Approval for Class and Properties.
(1) Equipment shall be identified not
only for the class of location but also
for the explosive, combustible, or
ignitible properties of the specific gas,
vapor, dust, fiber, or flyings that will be
present. In addition, Class I equipment
shall not have any exposed surface
that operates at a temperature in
excess of the ignition temperature of
the specific gas or vapor. Class II
equipment shall not have an external
temperature higher than that specified
in 500.8(C)(2). Class III equipment
shall not exceed the maximum surface
temperatures specified in 503.5.
500.8 Equipment.
(B) Approval for Class and Properties.
(1) Equipment shall be identified not
only for the class of location but also
for the explosive, combustible, or
ignitible properties of the specific gas,
vapor, dust, or fibers/flyings that will be
present. In addition, Class I equipment
shall not have any exposed surface
that operates at a temperature in
excess of the ignition temperature of
the specific gas or vapor. Class II
equipment shall not have an external
temperature higher than that specified
in 500.8(D)(2). Class III equipment
shall not exceed the maximum surface
temperatures specified in 503.5.
500.8 Equipment.
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Change Description and Impact to
Worker Safety
requirements for determining suitability
of equipment.
As Safe or Safer.
Revised to replace ‘‘ignitible fibers or
flyings’’ with ‘‘ignitible fibers/flyings’’.
As Safe or Safer.
Clarified that the required temperature
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(B) Marking.
(C) Marking.
(5) Ambient Temperature Range. For
equipment rated for a temperature
range other than –25°C to +40°C, the
marking shall specify the special range
of ambient temperatures. The marking
shall include either the symbol “Ta” or
“Tamb.”
Class I Locations
(5) Ambient Temperature Range. For
equipment rated for a temperature
range other than –25°C to +40°C, the
marking shall specify the special range
of ambient temperatures in degrees
Celsius. The marking shall include
either the symbol “Ta” or “Tamb.”
Article 501
Class I Locations
501.10 Wiring Methods.
501.10 Wiring Methods.
(A) Class I, Division 1.
(A) Class I, Division 1.
(1) General.
(1) General.
Exception: Rigid nonmetallic conduit
complying with Article 352 shall be
permitted where encased in a concrete
envelope……
501.10 Wiring Methods.
Exception: Type PVC conduit and
Type RTRC conduit shall be permitted
where encased in a concrete
envelope…..
501.10 Wiring Methods.
(B) Class I, Division 2.
(B) Class I, Division 2.
(1) General.
(1) General.
Change Description and Impact to
Worker Safety
range marking is to be in degrees
Celsius.
As Safe or Safer.
Revised to permit PVC and RTRC
types of nonmetallic conduit.
As Safe or Safer.
Deleted requirement for all single
conductor MV cables to be shielded or
metallic armored where not required by
Chapter 3.
As Safe or Safer.
(6) Type MI, MC, MV, or TC cable with
termination fittings, or in cable tray
(6) Type MI, MC, MV, or TC cable with
termination fittings, or in cable tray
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systems and installed in a manner to
avoid tensile stress at the termination
fittings. Single conductor Type MV
cables shall be shielded or metallic
armored.
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Change Description and Impact to
Worker Safety
systems and installed in a manner to
avoid tensile stress at the termination
fittings.

501.10 Wiring Methods.
(B) Class I, Division 2.
Added new section for provisions on
the use of Schedule 80 PVC and
RTRC types of nonmetallic conduit in
Class I, Division 2 locations.
(1) General.
As Safe or Safer.
(7) In industrial establishments with
restricted public access where the
conditions of maintenance and
supervision ensure that only qualified
persons service the installation and
where metallic conduit does not
provide sufficient corrosion resistance,
reinforced thermosetting resin conduit
(RTRC), factory elbows, and
associated fittings, all marked with the
suffix -XW, and Schedule 80 PVC
conduit, factory elbows, and
associated fittings shall be permitted.
Where seals are required for boundary
conditions as defined in 501.15(A)(4),
the Division 1 wiring method shall
extend into the Division 2 area to the
seal, which shall be located on the
Division 2 side of the Division 1–
Division 2 boundary.
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501.30 Grounding and Bonding, Class
I, Divisions 1 and 2.
501.30 Grounding and Bonding, Class
I, Divisions 1 and 2.
(B) Types of Equipment Grounding
Conductors. Where flexible metal
conduit or liquidtight flexible metal
conduit is used as permitted in
501.10(B) and is to be relied on to
complete a sole equipment grounding
path, it shall be installed with internal
or external bonding jumpers in parallel
with each conduit and complying with
250.102.
501.35 Surge Protection.
(B) Types of Equipment Grounding
Conductors. Flexible metal conduit and
liquidtight flexible metal conduit shall
not be used as the sole ground-fault
current path. Where equipment
bonding jumpers are installed, they
shall comply with 250.102.
(A) Class I, Division 1. Surge arresters,
transient voltage surge suppressors
(TVSS), and capacitors shall be
installed in enclosures identified for
Class I, Division 1 locations. Surgeprotective capacitors shall be of a type
designed for specific duty.
(A) Class I, Division 1. Surge arresters,
surge-protective devices, and
capacitors shall be installed in
enclosures identified for Class I,
Division 1 locations. Surge-protective
capacitors shall be of a type designed
for specific duty.
501.35 Surge Protection.
501.35 Surge Protection.
(B) Class I, Division 2. Surge arresters
and TVSS shall be nonarcing, such as
metal-oxide varistor (MOV) sealed
type, and surge-protective capacitors
shall be of a type designed for specific
duty. Enclosures shall be permitted to
(B) Class I, Division 2. Surge arresters
and surge-protective devices shall be
nonarcing, such as metal-oxide
varistor (MOV) sealed type, and surgeprotective capacitors shall be of a type
designed for specific duty. Enclosures
501.35 Surge Protection.
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Change Description and Impact to
Worker Safety
Clarified that flexible metal conduit and
liquidtight flexible metal conduit cannot
be used as the sole ground-fault
current path and that an internal or
external bonding jumper is required.
As Safe or Safer.
Revised to correlate with changes
made in Articles 280 and 285 and UL
1449.
As Safe or Safer.
Revised to correlate with changes
made in Articles 280 and 285 and UL
1449.
As Safe or Safer.
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be of the general-purpose type. Surge
protection of types other than
described in this paragraph shall be
installed in enclosures identified for
Class I, Division 1 locations.
III. Equipment
shall be permitted to be of the generalpurpose type. Surge protection of
types other than described in this
paragraph shall be installed in
enclosures identified for Class I,
Division 1 locations.
III. Equipment
501.100 Transformers and Capacitors.
501.100 Transformers and Capacitors.
Revised to permit transformers
identified for Class I locations to be
installed without a vault.
(A) Class I, Division 1.
(A) Class I, Division 1.
As Safe or Safer.
(2) Not Containing Liquid That Will
Burn. Transformers and capacitors that
do not contain a liquid that will burn
shall be installed in vaults complying
with 501.100(A)(1) or be approved for
Class I locations.
(2) Not Containing Liquid That Will
Burn. Transformers and capacitors that
do not contain a liquid that will burn
shall be installed in vaults complying
with 501.100(A)(1) or be identified for
Class I locations.
Article 502
Class II Locations
Deleted performance requirement on
surface temperatures of equipment
502.5 Explosionproof Equipment.
because it is covered by 500.8(D)(2).
Class II Locations
502.5 General. The general rules of
this Code shall apply to the electric
wiring and equipment in locations
classified as Class II locations in
500.5(C).
Change Description and Impact to
Worker Safety
As Safe or Safer.
Equipment installed in Class II
locations shall be able to function at full 
rating without developing surface
temperatures high enough to cause
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Change Description and Impact to
Worker Safety
excessive dehydration or gradual
carbonization of any organic dust
deposits that may occur.
Explosionproof equipment and wiring
shall not be required and shall not be
acceptable in Class II locations unless
identified for such locations.
II. Wiring
Explosionproof equipment and wiring
shall not be required and shall not be
acceptable in Class II locations unless
identified for such locations.
II. Wiring
502.10 Wiring Methods.
502.10 Wiring Methods.
(A) Class II, Division 1.
(A) Class II, Division 1.
(1) General.
(1) General.
(3) In industrial establishments with
limited public access, where the
conditions of maintenance and
supervision ensure that only qualified
persons service the installation, Type
MC cable, listed for use in Class II,
Division 1 locations, with a
gas/vaportight continuous corrugated
metallic sheath, an overall jacket of
suitable polymeric material, separate
grounding conductors in accordance
with 250.122, and provided with
termination fittings listed for the
application, shall be permitted.
502.30 Grounding and Bonding, Class
(3) In industrial establishments with
limited public access, where the
conditions of maintenance and
supervision ensure that only qualified
persons service the installation, Type
MC-HL cable, listed for use in Class II,
Division 1 locations, with a
gas/vaportight continuous corrugated
metallic sheath, an overall jacket of
suitable polymeric material, a separate
equipment grounding conductor(s) in
accordance with 250.122, and
provided with termination fittings listed
for the application, shall be permitted.
502.30 Grounding and Bonding, Class
Clarified that listed MC cable must be
marked MC-HL.
As Safe or Safer.
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Clarified that flexible metal conduit and
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II, Divisions 1 and 2.
II, Divisions 1 and 2.
(B) Types of Equipment Grounding
Conductors. Where flexible conduit is
used as permitted in 502.10, it shall be
installed with internal or external
bonding jumpers in parallel with each
conduit and complying with 250.102.
(B) Types of Equipment Grounding
Conductors. Liquidtight flexible metal
conduit shall not be used as the sole
ground-fault current path. Where
equipment bonding jumpers are
installed, they shall comply with
250.102.
502.35 Surge Protection — Class II,
Divisions 1 and 2. Surge arresters and
surge-protective devices installed in a
Class II, Division 1 location shall be in
suitable enclosures. Surge-protective
capacitors shall be of a type designed
for specific duty.
502.35 Surge Protection — Class II,
Divisions 1 and 2. Surge arresters and
transient voltage surge suppressors
(TVSS) installed in a Class II, Division
1 location shall be in suitable
enclosures. Surge-protective
capacitors shall be of a type designed
for specific duty.
502.115 Switches, Circuit Breakers,
Motor Controllers, and Fuses.
502.115 Switches, Circuit Breakers,
Motor Controllers, and Fuses.
Change Description and Impact to
Worker Safety
liquidtight flexible metal conduit cannot
be used as the sole ground-fault
current path and that an internal or
external bonding jumper is required.
As Safe or Safer.
Revised to correlate with changes
made in Articles 280 and 285 and UL
1449.
As Safe or Safer.
(A) Class II, Division 1.
(A) Class II, Division 1.
Deleted provisions permitting isolating
and disconnecting switches to be
installed in other than dustignitionproof enclosures.
(2) Isolating Switches. Disconnecting
and isolating switches containing no
fuses and not intended to interrupt
current and not installed where dusts
may be of an electrically conductive
nature shall be provided with tight
metal enclosures that shall be
designed to minimize the entrance of
dust and that shall (1) be equipped

As Safe or Safer.
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with telescoping or close-fitting covers
or with other effective means to
prevent the escape of sparks or
burning material and (2) have no
openings (such as holes for
attachment screws) through which,
after installation, sparks or burning
material might escape or through
which exterior accumulations of dust or
adjacent combustible material might be
ignited.
502.120 Control Transformers and
502.120 Control Transformers and
Resistors.
Resistors.
(B) Class II, Division 2.
Change Description and Impact to
Worker Safety
Revised to include dusttight enclosures
and set effective date after which all
enclosures are required to be dusttight.
(B) Class II, Division 2.
As Safe or Safer.
(2) Coils and Windings. Where not
located in the same enclosure with
switching mechanisms, control
transformers, solenoids, and
impedance coils shall be provided with
tight metal housings without ventilating
openings.
502.130 Luminaires.
(2) Coils and Windings. Where not
located in the same enclosure with
switching mechanisms, control
transformers, solenoids, and
impedance coils shall be provided with
tight metal housings without ventilating
openings or shall be installed in
dusttight enclosures. Effective January
1, 2011, only dusttight enclosures shall
be permitted.
502.130 Luminaires.
(B) Class II, Division 2.
(B) Class II, Division 2.
(2) Fixed Lighting. Luminaires (lighting
(2) Fixed Lighting. Luminaires for fixed
Page 242 of 361
Revised to require luminaires for fixed
lighting be identified for Class II
locations or be provided with dusttight
enclosures.
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fixtures) for fixed lighting, where not of
a type identified for Class II locations,
shall provide enclosures for lamps and
lampholders that shall be designed to
minimize the deposit of dust on lamps
and to prevent the escape of sparks,
burning material, or hot metal. Each
fixture shall be clearly marked to
indicate the maximum wattage of the
lamp that shall be permitted without
exceeding an exposed surface
temperature in accordance with
500.8(C)(2) under normal conditions of
use.
502.150 Signaling, Alarm, RemoteControl, and Communications
Systems; and Meters, Instruments, and
Relays.
lighting, where not of a type identified
for Class II locations, shall be provided
with dusttight enclosures. Each fixture
shall be clearly marked to indicate the
maximum wattage of the lamp that
shall be permitted without exceeding
an exposed surface temperature in
accordance with 500.8(D)(2) under
normal conditions of use.
(B) Class II, Division 2.
(1) Contacts. Enclosures shall comply
with 502.150(A)(2), or contacts shall
have tight metal enclosures designed
to minimize the entrance of dust and
shall have telescoping or tight-fitting
covers and no openings through which,
after installation, sparks or burning
material might escape.
Change Description and Impact to
Worker Safety
As Safe or Safer.
502.150 Signaling, Alarm, RemoteRevised to include dusttight enclosures
Control, and Communications
and set effective date after which all
Systems; and Meters, Instruments, and enclosures are required to be dusttight.
Relays.
As Safe or Safer.
(B) Class II, Division 2.
(1) Contacts. Contacts shall comply
with 502.150(A)(1), or contacts shall
have tight metal enclosures designed
to minimize the entrance of dust and
shall have telescoping or tight-fitting
covers and no openings through which,
after installation, sparks or burning
material might escape or shall be
installed in dusttight enclosures.
Effective January 1, 2011, only
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Change Description and Impact to
Worker Safety
dusttight enclosures shall be permitted.
502.150 Signaling, Alarm, Remote502.150 Signaling, Alarm, RemoteAdded reference to 502.120(B)(2) for
Control, and Communications
Control, and Communications
the type of enclosure, which includes
Systems; and Meters, Instruments, and Systems; and Meters, Instruments, and dusttight enclosures.
Relays.
Relays.
As Safe or Safer.
(B) Class II, Division 2.
(B) Class II, Division 2.
(2) Transformers and Similar
Equipment. The windings and terminal
connections of transformers, choke
coils, and similar equipment shall be
provided with tight metal enclosures
without ventilating openings.
502.150 Signaling, Alarm, RemoteControl, and Communications
Systems; and Meters, Instruments, and
Relays.
(2) Transformers and Similar
Equipment. The windings and terminal
connections of transformers, choke
coils, and similar equipment shall
comply with 502.120(B)(2).
502.150 Signaling, Alarm, RemoteControl, and Communications
Systems; and Meters, Instruments, and
Relays.
Added reference to 502.120(B)(3) for
the type of enclosure. Deleted
exception for (3) in lieu of the modified
compliance statement.
(B) Class II, Division 2.
(B) Class II, Division 2.
As Safe or Safer.
(3) Resistors and Similar Equipment.
Resistors, resistance devices,
thermionic tubes, rectifiers, and similar
equipment shall comply with
502.130(A)(3).
(3) Resistors and Similar Equipment.
Resistors, resistance devices,
thermionic tubes, rectifiers, and similar
equipment shall comply with
502.120(B)(3).
Exception: Enclosures for thermionic
tubes, nonadjustable resistors, or
rectifiers for which maximum operating
temperature will not exceed 120°C

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Change Description and Impact to
Worker Safety
(248°F) shall be permitted to be of the
general-purpose type.
502.150 Signaling, Alarm, RemoteControl, and Communications
Systems; and Meters, Instruments, and
Relays.
502.150 Signaling, Alarm, RemoteDeleted (5) as it was redundant.
Control, and Communications
Systems; and Meters, Instruments, and As Safe or Safer.
Relays.
(B) Class II, Division 2.
(B) Class II, Division 2.
(5) Wiring Methods. The wiring method
shall comply with 502.10(B).

Class III Locations
Article 503
Class III Locations
I. General
503.1 Scope. Article 503 covers the
requirements for electrical and
electronic equipment and wiring for all
voltages in Class III, Division 1 and 2
locations where fire or explosion
hazards may exist due to ignitible
fibers or flyings.
503.30 Grounding and Bonding —
Class III, Divisions 1 and 2.
I. General
503.1 Scope. Article 503 covers the
requirements for electrical and
electronic equipment and wiring for all
voltages in Class III, Division 1 and 2
locations where fire or explosion
hazards may exist due to ignitible
fibers/flyings.
503.30 Grounding and Bonding —
Class III, Divisions 1 and 2.
(B) Types of Equipment Grounding
Conductors. Where flexible conduit is
used as permitted in 503.10, it shall be
installed with internal or external
bonding jumpers in parallel with each
(B) Types of Equipment Grounding
Conductors. Liquidtight flexible metal
conduit shall not be used as the sole
ground-fault current path. Where
equipment bonding jumpers are
Page 245 of 361
Replaced ‘‘ignitible fibers or flyings’’
with ‘‘ignitible fibers/flyings’’ in the
scope and other sections.
As Safe or Safer.
Clarified that flexible metal conduit and
liquidtight flexible metal conduit cannot
be used as the sole ground-fault
current path and that an internal or
external bonding jumper is required.
As Safe or Safer.
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conduit and complying with 250.102.
Intrinsically Safe Systems
2008 NEC
installed, they shall comply with
250.102.
Article 504
Intrinsically Safe Systems
Change Description and Impact to
Worker Safety
Clarified permitted wiring methods.
504.20 Wiring Methods. Intrinsically
safe apparatus and wiring shall be
permitted to be installed using any of
the wiring methods suitable for
unclassified locations, including
Chapter 7 and Chapter 8. Sealing shall
be as provided in 504.70, and
separation shall be as provided in
504.30.
504.30 Separation of Intrinsically Safe
Conductors.
504.20 Wiring Methods. Any of the
As Safe or Safer.
wiring methods suitable for unclassified
locations, including those covered by
Chapter 7 and Chapter 8, shall be
permitted for installing intrinsically safe
apparatus. Sealing shall be as
provided in 504.70, and separation
shall be as provided in 504.30.
(A) From Nonintrinsically Safe Circuit
Conductors.
(A) From Nonintrinsically Safe Circuit
Conductors.
(1) In Raceways, Cable Trays, and
Cables. Conductors of intrinsically safe
circuits shall not be placed in any
raceway, cable tray, or cable with
conductors of any nonintrinsically safe
circuit.
(1) In Raceways, Cable Trays, and
Cables. Conductors of intrinsically safe
circuits shall not be placed in any
raceway, cable tray, or cable with
conductors of any nonintrinsically safe
circuit.
504.30 Separation of Intrinsically Safe
Conductors.
Exception No. 3: Intrinsically safe
circuits in a Division 2 or Zone 2
location shall be permitted to be
installed in a raceway, cable tray, or
Page 246 of 361
Added two exceptions on intrinsically
safe and nonincendive field wiring
circuits sharing a common raceway,
cable, or cable tray in Division or Zone
2 locations and on intrinsically safe
circuits passing through a Division or
Zone 2 location in route to a Division 1,
Zone 0, or Zone 1 sharing a common
raceway, cable, or cable tray with
nonincendive field wiring circuits.
As Safe or Safer.
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Change Description and Impact to
Worker Safety
cable along with nonincendive field
wiring circuits when installed in
accordance with 504.30(B).
504.30 Separation of Intrinsically Safe
Conductors.
Exception No. 4: Intrinsically safe
circuits passing through a Division 2 or
Zone 2 location to supply apparatus
that is located in a Division 1, Zone 0
or Zone 1 location shall be permitted to
be installed in a raceway, cable tray, or
cable along with nonincendive field
wiring circuits when installed in
accordance with 504.30(B).
504.30 Separation of Intrinsically Safe
Conductors.
(A) From Nonintrinsically Safe Circuit
Conductors.
(A) From Nonintrinsically Safe Circuit
Conductors.
(2) Within Enclosures.
(2) Within Enclosures. Conductors of
intrinsically safe circuits shall be
separated from conductors of
nonintrinsically safe circuits by one of
the following means:
Added three methods to separate
intrinsically safe circuits from
nonintrinsically safe circuits in
enclosures.
As Safe or Safer.
(1) Conductors of intrinsically safe
circuits shall be separated at least 50
mm (2 in.) from conductors of any
nonintrinsically safe circuits, or as
specified in 504.30(A)(2).
(2) All conductors shall be secured so
that any conductor that might come
loose from a terminal cannot come in
contact with another terminal.
(1) Separation by at least 50 mm (2 in.)
from conductors of any nonintrinsically
safe circuits.
(2) Separation from conductors of
nonintrinsically safe circuits by use of a
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Change Description and Impact to
Worker Safety
grounded metal partition 0.91 mm
(0.0359 in.) or thicker.
(3) Separation from conductors of
nonintrinsically safe circuits by use of
an approved insulating partition.
504.50 Grounding.
(4) Where either (1) all of the
intrinsically safe circuit conductors or
(2) all of the nonintrinsically safe circuit
conductors are in grounded metalsheathed or metalclad cables where
the sheathing or cladding is capable of
carrying fault current to ground.
504.50 Grounding.
(A) Intrinsically Safe Apparatus,
Associated Apparatus, and Raceways.
Intrinsically safe apparatus, associated
apparatus, cable shields, enclosures,
and raceways, if of metal, shall be
grounded.
504.50 Grounding.
(A) Intrinsically Safe Apparatus,
Enclosures, and Raceways.
Intrinsically safe apparatus,
enclosures, and raceways, if of metal,
shall be connected to the equipment
grounding conductor.
504.50 Grounding.
(B) Associated Apparatus and Cable
Shields. Associated apparatus and
cable shields shall be grounded in
accordance with the required control
drawing. See 504.10(A).
(B) Connection to Grounding
(C) Connection to Grounding
Page 248 of 361
Continued emphasis on connected to
an equipment grounding conductor
versus just grounded.
As Safe or Safer.
Added requirement for associated
apparatus and cable shields to be
grounded in accordance with the
control diagram. Old section (C)
incorporated into new Section (B).
As Safe or Safer.
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Electrodes. Where connection to a
grounding electrode is required, the
grounding electrode shall be as
specified in 250.52(A)(1), (A)(2), (A)(3),
and (A)(4) and shall comply with
250.30(A)(7). Section 250.52(A)(5),
(A)(6), and (A)(7) shall not be used if
electrodes specified in 250.52(A)(1),
(A)(2), (A)(3), or (A)(4) are available.
Electrodes. Where connection to a
grounding electrode is required, the
grounding electrode shall be as
specified in 250.52(A)(1), (A)(2), (A)(3),
and (A)(4) and shall comply with
250.30(A)(7). Sections 250.52(A)(5),
(A)(7), and (A)(8) shall not be used if
any of the electrodes specified in
250.52(A)(1), (A)(2), (A)(3), or (A)(4)
are present.
(C) Shields. Where shielded
conductors or cables are used, shields
shall be grounded.
Exception: Where a shield is part of an
intrinsically safe circuit.
504.70 Sealing. Conduits and cables
that are required to be sealed by
501.15, 502.15, and 505.16 shall be
sealed to minimize the passage of
gases, vapors, or dusts. Such seals
shall not be required to be
explosionproof or flameproof.
Change Description and Impact to
Worker Safety

Class I, Zone 0, 1, and 2 Locations
504.70 Sealing. Conduits and cables
that are required to be sealed by
501.15, 502.15, 505.16, and 506.16
shall be sealed to minimize the
passage of gases, vapors, or dusts.
Such seals shall not be required to be
explosionproof or flameproof but shall
be identified for the purpose of
minimizing passage of gases, vapors,
or dusts under normal operating
conditions and shall be accessible.
Article 505
Class I, Zone 0, 1, and 2 Locations
505.7 Special Precaution. Article 505
505.7 Special Precaution. Article 505
Page 249 of 361
Revised to require that seals be
identified for the purpose of minimizing
passage of gases, vapors, or dust
under normal operating conditions and
for seals to be accessible.
As Safe or Safer.
Revised to require that all functions
associated with using the zone
classification system for electrical
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requires equipment construction and
installation that ensures safe
performance under conditions of
proper use and maintenance.
requires equipment construction and
installation that ensures safe
performance under conditions of
proper use and maintenance.
(A) Supervision of Work. Classification
of areas and selection of equipment
and wiring methods shall be under the
supervision of a qualified Registered
Professional Engineer.
505.8 Protection Techniques.
(A) Implementation of Zone
Classification System. Classification of
areas, engineering and design,
selection of equipment and wiring
methods, installation, and inspection
shall be performed by qualified
persons.
505.8 Protection Techniques.
505.8 Protection Techniques.
(I) Encapsulation “mb”. This protection
technique shall be permitted for
equipment in Class I, Zone 1 or Zone 2
locations.
505.8 Protection Techniques.
Change Description and Impact to
Worker Safety
installations involve qualified persons.
As Safe or Safer.
Added to specify application of ‘‘ma’’
and ‘‘mb’’ encapsulation protection
(H) Encapsulation “ma”. This protection techniques.
technique shall be permitted for
equipment in Class I, Zone 0, Zone 1,
As Safe or Safer.
or Zone 2 locations.
(I) Combustible Gas Detection System.
(K) Combustible Gas Detection
System.
(1) Inadequate Ventilation. In a Class I,
Zone 1 location that is so classified
due to inadequate ventilation, electrical
(1) Inadequate Ventilation. In a Class I,
Zone 1 location that is so classified
due to inadequate ventilation, electrical
Added listing requirements for specific
applications of combustible gas
detection equipment.
As Safe or Safer.
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equipment suitable for Class I, Zone 2
locations shall be permitted.
equipment suitable for Class I, Zone 2
locations shall be permitted.
Combustible gas detection equipment
shall be listed for Class I, Zone 1, for
the appropriate material group, and for
the detection of the specific gas or
vapor to be encountered.
505.8 Protection Techniques.
505.8 Protection Techniques.
(I) Combustible Gas Detection System.
(2) Interior of a Building. In a building
located in, or with an opening into, a
Class I, Zone 2 location where the
interior does not contain a source of
flammable gas or vapor, electrical
equipment for unclassified locations
shall be permitted.
505.8 Protection Techniques.
(I) Combustible Gas Detection System.
(3) Interior of a Control Panel. In the
interior of a control panel containing
instrumentation utilizing or measuring
(K) Combustible Gas Detection
System.
Change Description and Impact to
Worker Safety
Added listing requirements for specific
applications of combustible gas
detection equipment.
As Safe or Safer.
(2) Interior of a Building. In a building
located in, or with an opening into, a
Class I, Zone 2 location where the
interior does not contain a source of
flammable gas or vapor, electrical
equipment for unclassified locations
shall be permitted. Combustible gas
detection equipment shall be listed
for Class I, Zone 1 or Class I, Zone 2,
for the appropriate material group, and
for the detection of the specific gas or
vapor to be encountered.
505.8 Protection Techniques.
(K) Combustible Gas Detection
System.
Added listing requirements for specific
applications of combustible gas
detection equipment.
As Safe or Safer.
(3) Interior of a Control Panel. In the
interior of a control panel containing
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flammable liquids, gases, or vapors,
electrical equipment suitable for Class
I, Zone 2 locations shall be permitted.
505.9 Equipment.
instrumentation utilizing or measuring
flammable liquids, gases, or vapors,
electrical equipment suitable for Class
I, Zone 2 locations shall be permitted.
Combustible gas detection equipment
shall be listed for Class I, Zone 1, for
the appropriate material group, and for
the detection of the specific gas or
vapor to be encountered.
505.9 Equipment.
(C) Marking.
(C) Marking.
(2) Zone Equipment. ………..Electrical
equipment of types of protection “e,”
“m,” “p,” or “q” shall be marked Group
II.
(2) Zone Equipment. ………..Electrical
equipment of types of protection “e,”
“m,” “ma,” “mb,” “px,” “py,” “pz,” or “q”
shall be marked Group II…….
Change Description and Impact to
Worker Safety
Included encapsulation types ‘‘ma’’
and ‘‘mb,’’ replaced pressurization type
‘‘p’’ with ‘‘px, ‘‘py,’’ and ‘‘pz,’’ and
added a note to identify the conditions
under which associated apparatus can
be installed in hazardous locations.
As Safe or Safer.
Table 505.9(C)(2)(4) Types of
Protection Designation
505.9 Equipment.
**Associated apparatus is permitted to
be installed in a hazardous (classified)
location if suitably protected using
another type of protection.
505.9 Equipment.
(D) Class I Temperature.
(D) Class I Temperature.
(1) Temperature Classifications.
(1) Temperature Classifications.
Clarified that the required temperature
range marking is to be in degrees
Celsius. Moved commentary to a new
Fine Print Note.
As Safe or Safer.
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………….Electrical equipment that is
designed for use in a range of ambient
temperatures other than −20°C and
+40°C is considered to be special; and
the ambient temperature range shall
then be marked on the equipment,
including either the symbol “Ta” or
“Tamb” together with the special range
of ambient temperatures. As an
example, such a marking might be
“−30°C ≤ Ta ≤ + 40°C.”
505.9 Equipment.
…………..Electrical equipment that is
designed for use in a range of ambient
temperatures other than −20°C to
+40°C is considered to be special; and
the ambient temperature range shall
then be marked on the equipment,
including either the symbol “Ta” or
“Tamb” together with the special range
of ambient temperatures, in degrees
Celsius.
505.9 Equipment.
505.15 Wiring Methods.
(F) Fiber Optic Cable Assembly.
Where a fiber optic cable assembly
contains conductors that are capable
of carrying current, the fiber optic cable
assembly shall be installed in
accordance with 505.15 and 505.16,
as applicable.
505.15 Wiring Methods.
(C) Class I, Zone 2.
(C) Class I, Zone 2.
(1) General.
(1) General.
(g) In industrial establishments with
restricted public access where the
conditions of maintenance and
supervision ensure that only qualified
persons service the installation and
Page 253 of 361
Change Description and Impact to
Worker Safety
Added requirement on the installation
of fiber optic cable assemblies.
As Safe or Safer.
Added provisions on the use of
Schedule 80 PVC and RTRC types of
nonmetallic conduit in Class I, Zone 2
locations by inserting new section (g)
ahead of the existing section (g) and
renumbering it (h).
As Safe or Safer.
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505.17 Flexible Cords, Class I, Zones
1 and 2.
where metallic conduit does not
provide sufficient corrosion resistance,
reinforced thermosetting resin conduit
(RTRC), factory elbows, and
associated fittings, all marked with the
suffix -XW, and Schedule 80 PVC
conduit, factory elbows, and
associated fittings shall be permitted.
Where seals are required for boundary
conditions as defined in
505.16(C)(1)(b), the Zone 1 wiring
method shall extend into the Zone 2
area to the seal, which shall be located
on the Zone 2 side of the Zone 1–Zone
2 boundary.
505.17 Flexible Cords, Class I, Zones
1 and 2.
505.25 Grounding and Bonding.
(6) Cord entering an increased safety
“e” enclosure shall be terminated with
a listed increased safety “e” cord
connector.
505.25 Grounding and Bonding.
(B) Types of Equipment Grounding
Conductors. Where flexible metal
conduit or liquidtight flexible metal
conduit is used as permitted in
505.15(C) and is to be relied on to
complete a sole equipment grounding
path, it shall be installed with internal
(B) Types of Equipment Grounding
Conductors. Flexible metal conduit and
liquidtight flexible metal conduit shall
not be used as the sole ground-fault
current path. Where equipment
bonding jumpers are installed, they
shall comply with 250.102.
Page 254 of 361
Change Description and Impact to
Worker Safety
Added requirement for cord connectors
entering safety ‘‘e’’ enclosures.
As Safe or Safer.
Clarified that flexible metal conduit and
liquidtight flexible metal conduit cannot
be used as the sole ground-fault
current path and that an internal or
external bonding jumper is required.
As Safe or Safer.
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Change Description and Impact to
Worker Safety
or external bonding jumpers in parallel
with each conduit and complying with
250.102.
Article 506
Zone 20, 21, and 22 Locations for
Zone 20, 21, and 22 Locations for
Combustible Dusts, Fibers, and Flyings Combustible Dusts or Ignitible
Fibers/Flyings
506.2 Definitions.
506.2 Definitions.
Protection by Encapsulation “mD.”
Type of protection where electrical
parts that could cause ignition of a
mixture of combustible dust or
fibers/flyings in air are protected by
enclosing them in a compound in such
a way that the explosive atmosphere
cannot be ignited.
Protection by Enclosure “tD.” Type of
protection for explosive dust
atmospheres where electrical
apparatus is provided with an
enclosure providing dust ingress
protection and a means to limit surface
temperatures.
Protection by Intrinsic Safety “iD.” Type
of protection where any spark or
thermal effect is incapable of causing
Page 255 of 361
Replaced ‘‘ignitible fibers or flyings’’
with ‘‘ignitible fibers/flyings’’ in the
scope and other sections.
As Safe or Safer.
Added definitions for protection by
encapsulation ’’mD,’’ enclosure ‘‘tD,’’
intrinsic safety ‘‘iD,’’ and pressurization
‘‘pD.’’
As Safe or Safer.
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Change Description and Impact to
Worker Safety
ignition of a mixture of combustible
dust, fibers, or flyings in air under
prescribed test conditions.
506.8 Protection Techniques.
Protection by Pressurization “pD.”
Type of protection that guards against
the ingress of a mixture of combustible
dust or fibers/flyings in air into an
enclosure containing electrical
equipment by providing and
maintaining a protective gas
atmosphere inside the enclosure at a
pressure above that of the external
atmosphere.
506.8 Protection Techniques.
(E) Encapsulation “maD”. This
protection technique shall be permitted
for equipment in Zone 20, Zone 21,
and Zone 22 locations for which it is
identified.
(F) Encapsulation “mbD”. This
protection technique shall be permitted
for equipment in Zone 21 and Zone 22
locations for which it is identified.
(E) Nonincendive Circuit. This
protection technique shall be permitted
for equipment in Zone 22 locations for
which it is identified.
(G) Nonincendive Circuit. This
protection technique shall be permitted
for equipment in Zone 22 locations for
which it is identified.
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• 506.8: Added section to specify
application of protection techniques:
encapsulation ‘‘maD,’’ encapsulation
‘‘mbD,’’ enclosure ‘‘tD,’’ pressurization
‘‘pD,’’ and intrinsic safety ‘‘iD.’’
As Safe or Safer.
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(F) Nonincendive Equipment. This
protection technique shall be permitted
for equipment in Zone 22 locations for
which it is identified.
(H) Nonincendive Equipment. This
protection technique shall be permitted
for equipment in Zone 22 locations for
which it is identified.
Change Description and Impact to
Worker Safety
(I) Protection by Enclosure “tD”. This
protection technique shall be permitted
for equipment in Zone 21 and Zone 22
locations for which it is identified.
(J) Protection by Pressurization “pD”.
This protection technique shall be
permitted for equipment in Zone 21
and Zone 22 locations for which it is
identified.
506.9 Equipment Requirements.
(C) Marking. Equipment identified for
Class II, Division 1 or Class II, Division
2 shall, in addition to being marked in
accordance with 500.8(B), be
permitted to be marked with both of the
following:
(1) Zone 20, 21, or 22 (as applicable)
(K) Protection by Intrinsic Safety “iD”.
This protection technique shall be
permitted for equipment in Zone 20,
Zone 21, and Zone 22 locations for
which it is listed.
506.9 Equipment Requirements.
Added new section for marking
requirements for zone equipment.
(C) Marking.
As Safe or Safer.
(1) Division Equipment. Equipment
identified for Class II, Division 1 or
Class II, Division 2 shall, in addition to
being marked in accordance with
500.8(C), be permitted to be marked
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(2) Temperature classification in
accordance with 506.9(D)
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Change Description and Impact to
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with both of the following:
(1) Zone 20, 21, or 22 (as
applicable)
(2) Temperature classification in
accordance with 506.9(D)
(2) Zone Equipment. Equipment
meeting one or more of the protection
techniques described in 506.8 shall be
marked with the following in the order
shown:
(1) Symbol “AEx”
(2) Protection technique(s) in
accordance with Table
506.9(C)(2)(2)
(3) Zone
(4) Temperature classification,
marked as a temperature value, in
degrees C, preceded by T
(5) Ambient temperature marking in
accordance with 506.9(D)
Table 506.9(C)(2)(2) Types of
Protection Designation
Added Table 506.9(C)(2)(2) providing
information on permitted zone
applications for protection techniques.
Designation – Technique – Zone
506.9 Equipment Requirements.
506.9 Equipment Requirements.
(F) Fiber Optic Cable Assembly.
Where a fiber optic cable assembly
contains conductors that are capable
Page 258 of 361
As Safe or Safer.
Added new section for requirements
on the installation of fiber optic cable
assemblies.
As Safe or Safer.
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506.15 Wiring Methods.
of carrying current, the fiber optic cable
assembly shall be installed in
accordance with 506.15 and 506.16,
as applicable.
506.15 Wiring Methods.
(A) Zone 20.
(A) Zone 20.
(3) In industrial establishments with
limited public access, where the
conditions of maintenance and
supervision ensure that only qualified
persons service the installation, Type
MC cable, listed for continuous use in
Zone 20 locations, with a
gas/vaportight continuous corrugated
metallic sheath, and overall jacket of
suitable polymeric material, separate
grounding conductors in accordance
with 250.122, and provided with
termination fittings listed for the
application, shall be permitted.
(3) In industrial establishments with
limited public access, where the
conditions of maintenance and
supervision ensure that only qualified
persons service the installation, Type
MC-HL cable, listed for use in Zone 20
locations, with a gas/vaportight
continuous corrugated metallic sheath
and overall jacket of suitable polymeric
material, a separate equipment
grounding conductor(s) in accordance
with 250.122, and provided with
termination fittings listed for the
application, shall be permitted.
Exception: MC cable and fittings listed
for Class II, Division 1 locations are
permitted to be used.
506.25 Grounding and Bonding.
Exception: Type MC-HL cable and
fittings listed for Class II, Division 1
locations are permitted to be used.
506.25 Grounding and Bonding.
(B) Types of Equipment Grounding
Conductors. Where flexible conduit is
used as permitted in 506.15, it shall be
(B) Types of Equipment Grounding
Conductors. Liquidtight flexible metal
conduit shall not be used as the sole
Change Description and Impact to
Worker Safety
Clarified that listed MC cable must be
marked MC-HL.
As Safe or Safer.
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Clarified that flexible metal conduit and
liquidtight flexible metal conduit cannot
be used as the sole ground-fault
current path and that an internal or
external bonding jumper is required.
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installed with internal or external
bonding jumpers in parallel with each
conduit and complying with 250.102.
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ground-fault current path. Where
equipment bonding jumpers are
installed, they shall comply with
250.102.
Article 511
Commercial Garages, Repair and
Storage
511.2 Definitions.
Major Repair Garage. A building or
portions of a building where major
repairs, such as engine overhauls,
painting, body and fender work, and
repairs that require draining of the
motor vehicle fuel tank are performed
on motor vehicles, including associated
floor space used for offices, parking, or
showrooms. [30A:3.3.12.1]
Minor Repair Garage. A building or
portions of a building used for
lubrication, inspection, and minor
automotive maintenance work, such as
engine tune-ups, replacement of parts,
fluid changes (e.g., oil, antifreeze,
transmission fluid, brake fluid, airconditioning refrigerants), brake
system repairs, tire rotation, and
similar routine maintenance work,
including associated floor space used
for offices, parking, or showrooms.
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As Safe or Safer.
Added definitions for major and minor
repair garages.
As Safe or Safer.
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511.3 Classifications of Locations.
(A) Unclassified Locations.
(1) Parking and Repair Garages.
Parking garages used for parking or
storage shall be permitted to be
unclassified. Repair garages shall be
permitted to be unclassified when
designed in accordance with
511.3(A)(2) through 511.3(A)(7).
(2) Alcohol-Based Windshield Washer
Fluid. The storage, handling, or
dispensing into motor vehicles of
alcohol based windshield washer fluid
in areas used for the service and repair
operations of the vehicles shall not
cause such areas to be classified as
hazardous (classified) locations.
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[30A:3.3.12.2]
511.3 Area Classification, General.
Where Class I liquids or gaseous fuels
are stored, handled, or transferred,
electrical wiring and electrical
utilization equipment shall be designed
in accordance with the requirements
for Class I, Division 1 or 2 hazardous
(classified) locations as classified in
accordance with 500.5 and 500.6, and
this article. A Class I location shall not
extend beyond an unpierced wall, roof,
or other solid partition that has no
openings. [30A:8.3.5, 8.3.2]
(A) Parking Garages. Parking garages
used for parking or storage shall be
permitted to be unclassified.
(B) Repair Garages, With Dispensing.
Major and minor repair garages that
(3) Specific Areas Adjacent to
dispense motor fuels into the fuel tanks
Classified Locations. Areas adjacent to of vehicles, including flammable liquids
classified locations in which flammable having a flash point below 38°C
vapors are not likely to be released,
(100°F) such as gasoline, or gaseous
such as stock rooms, switchboard
fuels such as natural gas, hydrogen, or
rooms, and other similar locations,
LPG, shall have the dispensing
shall not be classified where
functions and components classified in
mechanically ventilated at a rate of four accordance with Table 514.3(B)(1) in
or more air changes per hour, or
addition to any classification required
designed with positive air pressure, or
by this section. Where Class I liquids,
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Clarified area classification
requirements based on categories of
commercial repair and storage
garages.
As Safe or Safer.
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where effectively cut off by walls or
partitions.
(4) Pits in Lubrication or Service Room
Where Class I Liquids Are Not
Transferred. Any pit, belowgrade work
area, or subfloor work area that is
provided with exhaust ventilation at a
rate of not less than 0.3 m3/min/m2 (1
cfm/ft2) of floor area at all times that
the building is occupied or when
vehicles are parked in or over this area
and where exhaust air is taken from a
point within 300 mm (12 in.) of the floor
of the pit, belowgrade work area, or
subfloor work area is unclassified.
[NFPA 30A:7.4.5.4 and Table 8.3.1]
(5) Up to a Level of 450 mm (18 in.)
Above the Floor in Lubrication or
Service Rooms Where Class I Liquids
Are Transferred. For each floor, the
entire area up to a level of 450 mm (18
in.) above the floor shall be considered
unclassified where there is mechanical
ventilation providing a minimum of four
air changes per hour or one cubic foot
per minute of exchanged air for each
square foot of floor area. Ventilation
shall provide for air exchange across
the entire floor area, and exhaust air
2008 NEC
other than fuels, are dispensed, the
area within 900 mm (3 ft) of any fill or
dispensing point, extending in all
directions, shall be a Class I, Division 2
location.
(C) Major Repair Garages. Where
flammable liquids having a flash point
below 38°C (100°F) such as gasoline,
or gaseous fuels such as natural gas,
hydrogen, or LPG, will not be
dispensed, but repair activities that
involve the transfer of such fluids or
gases are performed, the classification
rules in (1), (2), and (3) shall apply.
(1) Floor Areas.
(a) Ventilation Provided. The floor
area shall be unclassified where
there is mechanical ventilation
providing a minimum of four air
changes per hour or one cubic foot
per minute of exchanged air for
each square foot of floor area.
Ventilation shall provide for air
exchange across the entire floor
area, and exhaust air shall be taken
at a point within 0.3 m (12 in.) of the
floor.
(b) Ventilation Not Provided. The
entire floor area up to a level of 450
mm (18 in.) above the floor shall be
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shall be taken at a point within 0.3 m
(12 in.) of the floor.
(6) Flammable Liquids Having Flash
Points Below 38°C (100°F). Where
flammable liquids having a flash point
below 38°C (100°F) (such as gasoline)
or gaseous fuels (such as natural gas,
hydrogen, or LPG) will not be
transferred, such location shall be
considered to be unclassified. Unless
the location is required to be classified
in accordance with 511.3(B)(2) or
(B)(4).
(7) Within 450 mm (18 in.) of the
Ceiling. In major repair garages, where
lighter-than-air gaseous fuels (such as
natural gas or hydrogen) vehicles are
repaired or stored, the area within 450
mm (18 in.) of the ceiling shall be
considered unclassified where
ventilation of at least 1 cfm/sq ft of
ceiling area taken from a point within
450 mm (18 in.) of the highest point in
the ceiling is provided.
(B) Classified Locations.
(1) Flammable Fuel Dispensing Areas.
Areas in which flammable fuel is
dispensed into vehicle fuel tanks shall
2008 NEC
classified as Class I, Division 2 if the
ventilation does not comply with
511.3(C)(1)(a).
(2) Ceiling Areas. Where lighterthan-air gaseous fueled vehicles,
such as vehicles fueled by natural
gas or hydrogen, are repaired or
stored, the area within 450 mm (18
in.) of the ceiling shall be considered
for classification in accordance with
(a) and (b).
(a) Ventilation Provided. The ceiling
area shall be unclassified where
ventilation is provided, from a point
not less than 450 mm (18 in.) from
the highest point in the ceiling, to
exhaust the ceiling area at a rate of
not less than 0.3 m3/min/m2 (1
cfm/ft2) of ceiling area at all times
that the building is occupied or when
vehicles using lighter-than-air
gaseous fuels are parked below this
area.
(b) Ventilation Not Provided. Ceiling
areas that are not ventilated in
accordance with 511.3(C)(2)(a) shall
be classified as Class I, Division 2.
(3) Pit Areas in Lubrication or
Service Room. Any pit, belowgrade
work area, or subfloor work area
shall be classified as provided in (a)
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conform to Article 514.
(2) Lubrication or Service Room Where
Class I Liquids or Gaseous Fuels
(Such as Natural Gas, Hydrogen, or
LPG) Are Not Transferred. The
following spaces that are not designed
in accordance with 511.3(A)(4) shall be
classified as Class I, Division 2:
(1) Entire area within any
unventilated pit, belowgrade work
area, or subfloor area.
(2) Area up to 450 mm (18 in.)
above any such unventilated pit,
belowgrade work area, or subfloor
work area and extending a distance
of 900 mm (3 ft) horizontally from
the edge of any such pit
belowgrade work area, or subfloor
work area.
(3) Lubrication or Service Room Where
Class I Liquids or Gaseous Fuels
(Such as Natural Gas, Hydrogen, or
LPG) Are Transferred. The following
spaces that are not designed in
accordance with 511.3(A)(5) shall be
classified as follows:
(1) Up to a Level of 450 mm (18 in.)
Above the Floor. For each floor, the
entire area up to a level of 450 mm
(18 in.) above the floor shall be a
Class I, Division 2 location.
or (b).
(a) Ventilation Provided. The pit
area shall be a Class I, Division 2
location where there is mechanical
ventilation providing a minimum of
six air changes per hour.
(b) Ventilation Not Provided. Where
ventilation is not provided in
accordance with 511.3(C)(3)(a), any
pit or depression below floor level
shall be a Class I, Division 1
location that extends up to the floor
level.
(D) Minor Repair Garages. Where
flammable liquids having a flash point
below 38°C (100°F) such as gasoline,
or gaseous fuels such as natural gas
or hydrogen, will not be dispensed or
transferred, the classification rules in
(D)(1), (D)(2), and (D)(3) shall apply to
the lubrication and service rooms.
(1) Floor Areas. Floor areas in minor
repair garages without pits,
belowgrade work areas, or subfloor
work areas shall be unclassified.
Where floor areas include pits,
belowgrade work areas, or subfloor
work areas in lubrication or service
rooms, the classification rules in (a)
or (b) shall apply.
(a) Ventilation Provided. The entire
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(2) Any Unventilated Pit or
Depression Below Floor Level.
Any unventilated pit or depression
below floor level shall be a Class I,
Division 1 location and shall extend
up to said floor level.
(3) Any Ventilated Pit or Depression
Below Floor Level. Any ventilated
pit or depression in which six air
changes per hour are exhausted
from a point within 300 mm (12 in.)
of the floor level of the pit shall be a
Class I, Division 2 location.
(4) Space Above an Unventilated
Pit or Depression Below Floor
Level. Above a pit, or depression
below floor level, the space up to
450 mm (18 in.) above the floor or
grade level and 900 mm (3 ft)
horizontally from a lubrication pit
shall be a Class I, Division location.
(5) Dispenser for Class I Liquids,
Other Than Fuels. Within 900 mm
(3 ft) of any fill or dispensing point,
extending in all directions shall be a
Class I, Division 2 location. See
also 511.3(B)(1).
(4) Within 450 mm (18 in.) of the
Ceiling. In major repair garages where
lighter-than-air gaseous fuel (such as
natural gas or hydrogen) vehicles are
2008 NEC
floor area shall be unclassified
where there is mechanical
ventilation providing a minimum of
four air changes per hour or one
cubic foot per minute of exchanged
air for each square foot of floor area.
Ventilation shall provide for air
exchange across the entire floor
area, and exhaust air shall be taken
at a point within 0.3 m (12 in.) of the
floor.
(b) Ventilation Not Provided. The
floor area up to a level of 450 mm
(18 in.) above any unventilated pit,
belowgrade work area, or subfloor
work area and extending a distance
of 900 mm (3 ft) horizontally from
the edge of any such pit,
belowgrade work area, or subfloor
work area, shall be classified as
Class I, Division 2.
(2) Ceiling Areas. Where lighterthan-air gaseous fuels (such as
natural gas or hydrogen) will not be
transferred, such locations shall be
unclassified.
(3) Pit Areas in Lubrication or
Service Room. Any pit, belowgrade
work area, or subfloor work area
shall be classified as provided in (a)
or (b).
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repaired or stored, ceiling spaces that
are not designed in accordance with
511.3(A)(7) shall be classified as Class
I, Division 2.
(a) Ventilation Provided. Where
ventilation is provided to exhaust the
pit area at a rate of not less than 0.3
m3/min/m2 (1 cfm/ft2) of floor area
at all times that the building is
occupied, or when vehicles are
parked in or over this area and
where exhaust air is taken from a
point within 300 mm (12 in.) of the
floor of the pit, belowgrade work
area, or subfloor work area, the pit
shall be unclassified. [30A:7.4.5.4.
Table 8.3.1]
(b) Ventilation Not Provided. Where
ventilation is not provided in
accordance with 511.3(D)(3)(a), any
pit or depression below floor level
shall be a Class I, Division 2
location that extends up to the floor
level.
(E) Modifications to Classification.
(1) Specific Areas Adjacent to
Classified Locations. Areas adjacent
to classified locations in which
flammable vapors are not likely to
be released, such as stock rooms,
switchboard rooms, and other
similar locations, shall be
unclassified where mechanically
ventilated at a rate of four or more
air changes per hour, or designed
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Change Description and Impact to
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with positive air pressure, or where
effectively cut off by walls or
partitions.
(2) Alcohol-Based Windshield
Washer Fluid. The area used for
storage, handling, or dispensing into
motor vehicles of alcohol-based
windshield washer fluid in repair
garages shall be unclassified unless
otherwise classified by a provision
of 511.3. [30A:8.3.5, Exception]

Article 513
Aircraft Hangars
513.2 Definitions. For the purpose of
this article, the following definitions
shall apply.
Aircraft Painting Hangar. An aircraft
hangar constructed for the express
purpose of spray/coating/dipping
applications and provided with
dedicated ventilation supply and
exhaust.
(C) Vicinity of Aircraft.
(1) Aircraft Maintenance and Storage
Hangars. The area within 1.5 m (5 ft)
horizontally from aircraft power plants
or aircraft fuel tanks shall be classified
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Added definition for an aircraft painting
hangar.
As Safe or Safer.
Added requirements on area
classification for aircraft painting
hangars.
As Safe or Safer.
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Change Description and Impact to
Worker Safety
as a Class I, Division 2 or Zone 2
location that shall extend upward from
the floor to a level 1.5 m (5 ft) above
the upper surface of wings and of
engine enclosures.
(2) Aircraft Painting Hangars. The area
within 3 m (10 ft) horizontally from
aircraft surfaces from the floor to 3 m
(10 ft) above the aircraft shall be
classified as Class I, Division 1 or
Class I, Zone 1. The area horizontally
from aircraft surfaces between 3.0 m
(10 ft) and 9.0 m (30 ft) from the floor
to 9.0 m (30 ft) above the aircraft
surface shall be classified as Class I,
Division 2 or Class I, Zone 2.
Bulk Storage Plants
Article 515
Bulk Storage Plants
515.7 Wiring and Equipment Above
Class I Locations.
515.7 Wiring and Equipment Above
Class I Locations.
Revised to permit Schedule 80 PVC
and RTRC types of nonmetallic
conduit.
As Safe or Safer.
(A) Fixed Wiring. All fixed wiring above
Class I locations shall be in metal
raceways or PVC Schedule 80 rigid
nonmetallic conduit, or equivalent, or
be Type MI, TC, or MC cable.
(A) Fixed Wiring. All fixed wiring above
Class I locations shall be in metal
raceways, Schedule 80 PVC conduit,
Type RTRC marked with the suffix XW, or Type MI, TC, or MC cable.
Article 516
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Spray Application, Dipping, and
Coating Processes
Spray Application, Dipping, and
Coating Processes
516.10 Special Equipment.
516.10 Special Equipment.
Change Description and Impact to
Worker Safety
Emphasis on connected to an
equipment grounding conductor versus
grounded.
As Safe or Safer.
(C) Powder Coating.
(C) Powder Coating.
(1) Electric Equipment and Sources of
Ignition. Electric equipment and other
sources of ignition shall comply with
the requirements of Article 502.
Portable electric lamps and other
utilization equipment shall not be used
within a Class II location during
operation of the finishing processes.
Where such lamps or utilization
equipment are used during cleaning or
repairing operations, they shall be of a
type identified for Class II, Division 1
locations, and all exposed metal parts
shall be effectively grounded.
(1) Electrical Equipment and Sources
of Ignition. Electrical equipment and
other sources of ignition shall comply
with the requirements of Article 502.
Portable electric luminaires and other
utilization equipment shall not be used
within a Class II location during
operation of the finishing processes.
Where such luminaires or utilization
equipment are used during cleaning or
repairing operations, they shall be of a
type identified for Class II, Division 1
locations, and all exposed metal parts
shall be connected to an equipment
grounding conductor.
Article 517
Health Care Facilities
Ambulatory Health Care Facility. A
building or part thereof used to provide
services or treatment to four or more
Ambulatory Health Care Occupancy. A
building or portion thereof used to
provide services or treatment
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Replaced the term patient vicinity with
patient care vicinity and wet location
with wet procedure location, for
correlation with changes to definitions
in 517.2.
Revised definitions of ambulatory
health care occupancy, limited care
facility, nursing home, and patient care
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patients at the same time and meeting
either (1) or (2).
(1) Those facilities that provide, on an
outpatient basis, treatment for patients
that would render them incapable of
taking action for self-preservation
under emergency conditions without
assistance from others, such as
hemodialysis units or freestanding
emergency medical units.
(2) Those facilities that provide, on an
outpatient basis, surgical treatment
requiring general anesthesia.
Limited Care Facility. A building or part
thereof used on a 24-hour basis for the
housing of four or more persons who
are incapable of self-preservation
because of age, physical limitation due
to accident or illness, or mental
limitations, such as mental
retardation/developmental disability,
mental illness, or chemical
dependency.
Nursing Home. A building or part
thereof used for the lodging, boarding,
and nursing care, on a 24-hour basis,
of four or more persons who, because
of mental or physical incapacity, may
be unable to provide for their own
2008 NEC
Change Description and Impact to
Worker Safety
vicinity for correlation with source
document, NFPA 99.
simultaneously to four or more patients
that provides, on an outpatient basis,
one or more of the following:
(1) Treatment for patients that renders As Safe or Safer.
the patients incapable of taking action
for self-preservation under emergency
conditions without assistance of others.
(2) Anesthesia that renders the
patients incapable of taking action for
self-preservation under emergency
conditions without the assistance of
others.
(3) Emergency or urgent care for
patients who, due to the nature of their
injury or illness, are incapable of taking
action for self-preservation under
emergency conditions without the
assistance of others. [101:3.3.168.1]
Limited Care Facility. A building or
portion thereof used on a 24-hour
basis for the housing of four or more
persons who are incapable of selfpreservation because of age; physical
limitation due to accident or illness; or
limitations such as mental
retardation/developmental disability,
mental illness, or chemical
dependency. [99:3.3.97]
Nursing Home. A building or portion of
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needs and safety without the
assistance of another person. Nursing
home, wherever used in this Code,
shall include nursing and convalescent
homes, skilled nursing facilities,
intermediate care facilities, and
infirmaries of homes for the aged.
a building used on a 24-hour basis for
the housing and nursing care of four or
more persons who, because of mental
or physical incapacity, might be unable
to provide for their own needs and
safety without the assistance of
another person. [99:3.3.129]
Patient Vicinity. In an area in which
patients are normally cared for, the
patient vicinity is the space with
surfaces likely to be contacted by the
patient or an attendant who can touch
the patient. Typically in a patient room,
this encloses a space within the room
not less than 1.8 m (6 ft) beyond the
perimeter of the bed in its nominal
location, and extending vertically not
less than 2.3 m (71⁄2 ft) above the
floor.
517.13 Grounding of Receptacles and
Fixed Electric Equipment in Patient
Care Areas. Wiring in patient care
areas shall comply with 517.13(A) and
517.13(B).
Patient Care Vicinity. In an area in
which patients are normally cared for,
the patient care vicinity is the space
with surfaces likely to be contacted by
the patient or an attendant who can
touch the patient. Typically in a patient
room, this encloses a space within the
room not less than 1.8 m (6 ft) beyond
the perimeter of the bed in its nominal
location, and extending vertically not
less than 2.3 m (71⁄2 ft) above the
floor. [99:3.3.140]
517.13 Grounding of Receptacles and
Fixed Electrical Equipment in Patient
Care Areas. Wiring in patient care
areas shall comply with 517.13(A) and
(B).
(A) Wiring Methods. All branch circuits
serving patient care areas shall be
provided with a ground path for fault
current by installation in a metal
raceway system, or a cable having a
(A) Wiring Methods. All branch circuits
serving patient care areas shall be
provided with an effective ground-fault
current path by installation in a metal
raceway system, or a cable having a
Page 271 of 361
Change Description and Impact to
Worker Safety
Continued emphasis on connected to
the equipment grounding conductor.
As Safe or Safer.
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metallic armor or sheath assembly.
The metal raceway system, or metallic
cable armor, or sheath assembly shall
itself qualify as an equipment
grounding return path in accordance
with 250.118.
metallic armor or sheath assembly.
The metal raceway system, or metallic
cable armor, or sheath assembly shall
itself qualify as an equipment
grounding conductor in accordance
with 250.118.
(B) Insulated Equipment Grounding
Conductor. The grounding terminals of
all receptacles and all non currentcarrying conductive surfaces of fixed
electric equipment likely to become
energized that are subject to personal
contact, operating at over 100 volts,
shall be grounded by an insulated
copper conductor. The equipment
grounding conductor shall be sized in
accordance with Table 250.122 and
installed in metal raceways or as a part
of listed cables having a metallic armor
or sheath assembly with the branchcircuit conductors supplying these
receptacles or fixed equipment.
(B) Insulated Equipment Grounding
Conductor. The grounding terminals of
all receptacles and all non currentcarrying conductive surfaces of fixed
electrical equipment likely to become
energized that are subject to personal
contact, operating at over 100 volts,
shall be connected to an insulated
copper equipment grounding
conductor. The equipment grounding
conductor shall be sized in accordance
with Table 250.122 and installed in
metal raceways or as a part of listed
cables having a metallic armor or
sheath assembly with the branchcircuit conductors supplying these
receptacles or fixed equipment.
Exception No. 1: Metal faceplates shall
be permitted to be grounded by means
of a metal mounting screw(s) securing
the faceplate to a grounded outlet box
or grounded wiring device.
Exception No. 2: Luminaires (light
Exception No. 1: Metal faceplates shall
be permitted to be connected to the
equipment grounding conductor by
means of a metal mounting screw(s)
securing the faceplate to a grounded
outlet box or grounded wiring device.
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Change Description and Impact to
Worker Safety
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fixtures) more than 2.3 m (71⁄2 ft)
above the floor and switches located
outside of the patient vicinity shall not
be required to be grounded by an
insulated equipment grounding
conductor.
2008 NEC
517.20 Wet Locations.
Exception No. 2: Luminaires more than
2.3 m (71⁄2 ft) above the floor and
switches located outside of the patient
care vicinity shall be permitted to be
connected to an equipment grounding
return path complying with 517.13(A).
517.20 Wet Procedure Locations.
(A) Receptacles and Fixed Equipment.
All receptacles and fixed equipment
within the area of the wet location
shall have ground-fault circuitinterrupter protection for personnel if
interruption of power under fault
conditions can be tolerated, or be
served by an isolated power system if
such interruption cannot be tolerated.
(A) Receptacles and Fixed Equipment.
All receptacles and fixed equipment
within the area of the wet procedure
location shall have ground-fault circuitinterrupter protection for personnel if
interruption of power under fault
conditions can be tolerated, or be
served by an isolated power system if
such interruption cannot be tolerated.
Exception: Branch circuits supplying
only listed, fixed, therapeutic and
diagnostic equipment shall be
permitted to be supplied from a normal
grounded service, single- or 3-phase
system, provided that
(a) Wiring for grounded and isolated
circuits does not occupy the same
raceway, and
(b) All conductive surfaces of the
equipment are grounded.
Exception: Branch circuits supplying
only listed, fixed, therapeutic and
diagnostic equipment shall be
permitted to be supplied from a
grounded service, single- or 3-phase
system, provided that
(a) Wiring for grounded and isolated
circuits does not
occupy the same raceway, and
(b) All conductive surfaces of the
equipment are connected to an
equipment grounding conductor.
Page 273 of 361
Change Description and Impact to
Worker Safety
Deleted the word ‘‘normal’’ in the
exception to clarify that the exception
applies to branch-circuit supplies from
any grounded supply system and
continued the emphasis on connected
to an equipment grounding conductor.
As Safe or Safer.
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517.32 Life Safety Branch.
517.32 Life Safety Branch.
(C) Alarm and Alerting Systems. Alarm
and alerting systems including the
following:
(C) Alarm and Alerting Systems. Alarm
and alerting systems including the
following:
(1) Fire alarms
(1) Fire alarms
(2) Alarms required for systems used
for the piping of nonflammable medical
gases
(2) Alarms required for systems used
for the piping of nonflammable medical
gases
517.32 Life Safety Branch.
(3) Mechanical, control, and other
accessories required for effective life
safety systems operation shall be
permitted to be connected to the life
safety branch.
517.32 Life Safety Branch.
Change Description and Impact to
Worker Safety
Revised to permit equipment and
circuits required for life safety system
operation to be supplied by life safety
branch.
As Safe or Safer.
(E) Generator Set Location. Task
illumination battery charger for
emergency battery-powered lighting
unit(s) and selected receptacles at the
generator set location.
517.34 Equipment System Connection
to Alternate Power Source.
(E) Generator Set and Transfer Switch
Locations. Task illumination battery
charger for battery-powered lighting
unit(s) and selected receptacles at the
generator set and essential transfer
switch locations. [99:4.4.2.2.2.2(5)]
(F) Generator Set Accessories.
Generator set accessories as required
for generator performance.
517.34 Equipment System Connection
to Alternate Power Source.
Page 274 of 361
Added section to permit generator set
accessories to be connected to the life
safety branch.
As Safe or Safer.
• 517.34(A)(7): Added section to permit
supply, return, and exhaust ventilating
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(A) Equipment for Delayed Automatic
Connection.
(A) Equipment for Delayed Automatic
Connection.
517.40 Essential Electrical Systems for
Nursing Homes and Limited Care
Facilities.
(7) Supply, return, and exhaust
ventilating systems for operating and
delivery rooms.
517.40 Essential Electrical Systems for
Nursing Homes and Limited Care
Facilities.
(B) Inpatient Hospital Care Facilities.
Nursing homes and limited care
facilities that provide inpatient hospital
care shall comply with the
requirements of Part III, 517.30
through 517.35.
517.44 Sources of Power.
(B) Alternate Source of Power.
Exception No. 2: Nursing homes or
limited care facilities meeting the
requirements of 517.40(A), Exception,
shall be permitted to use a battery
system or self-contained battery
integral with the equipment. [NFPA
Change Description and Impact to
Worker Safety
systems in operating and delivery
rooms to be arranged for delayed
automatic connection to the alternate
power source.
As Safe or Safer.
Revised description of ‘‘inpatient
hospital care facilities’’ for correlation
with NFPA 99.
(B) Inpatient Hospital Care Facilities.
As Safe or Safer.
For those nursing homes and limited
care facilities that admit patients who
need to be sustained by electrical life
support equipment, the essential
electrical system from the source to the
portion of the facility where such
patients are treated shall comply with
the requirements of Part III, 517.30
through 517.35.
517.44 Sources of Power.
Revised to permit health care facilities
other than nursing homes and limited
(B) Alternate Source of Power.
care facilities to use battery power for
the essential electrical system.
Exception No. 2: Nursing homes or
As Safe or Safer.
limited care facilities meeting the
requirement of 517.40(A) and other
health care facilities meeting the
requirement of 517.45 shall be
permitted to use a battery system or
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99:17.3.4.1.3, 18.3.4.1.1]
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Change Description and Impact to
Worker Safety
517.61 Wiring and Equipment.
self-contained battery integral with the
equipment.
517.61 Wiring and Equipment.
(C) Other-Than-Hazardous (Classified)
Anesthetizing Locations.
(C) Other-Than-Hazardous (Classified)
Anesthetizing Locations.
(2) Receptacles and Attachment Plugs.
Receptacles and attachment plugs
installed and used in other-thanhazardous (classified) locations shall
be listed for hospital use for services of
prescribed voltage, frequency, rating,
and number of conductors with
provision for connection of the
grounding conductor. This requirement
shall apply to 2-pole, 3-wire grounding
type for single phase, 120-, 208-, or
240-volt, nominal, ac service.
517.71 Connection to Supply Circuit.
(2) Receptacles and Attachment Plugs.
Receptacles and attachment plugs
installed and used in other-thanhazardous (classified) locations shall
be listed “hospital grade” for services
of prescribed voltage, frequency,
rating, and number of conductors with
provision for connection of the
grounding conductor. This requirement
shall apply to 2-pole, 3-wire grounding
type for single-phase, 120-, 208-, or
240-volt, nominal, ac service.
517.71 Connection to Supply Circuit.
Revised to specifically reference
Chapters 1 through 4 of the Code.
(A) Fixed and Stationary Equipment.
Fixed and stationary X-ray equipment
As Safe or Safer.
shall be connected to the power supply
by means of a wiring method
complying with applicable
requirements of Chapters 1 through 4
of this Code, as modified by this article.
VI. Communications, Signaling
Added provision that secondary
Systems, Data Systems, Fire Alarm
circuits of transformer-powered limited
Systems, and Systems Less Than 120 energy communications and signaling
(A) Fixed and Stationary Equipment.
Fixed and stationary X-ray equipment
shall be connected to the power supply
by means of a wiring method that
meets the general requirements of this
Code.
VI. Communications, Signaling
Systems, Data Systems, Fire Alarm
Systems, and Systems Less Than 120
Page 276 of 361
Clarified that the receptacles are
required to be listed as hospital grade.
As Safe or Safer.
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Volts, Nominal
Volts, Nominal
517.80 Patient Care Areas. Equivalent
insulation and isolation to that required
for the electrical distribution systems in
patient care areas shall be provided for
communications, signaling systems,
data system circuits, fire alarm
systems, and systems less than 120
volts, nominal.
VII. Isolated Power Systems
517.80 Patient Care Areas. Equivalent
insulation and isolation to that required
for the electrical distribution systems in
patient care areas shall be provided for
communications, signaling systems,
data system circuits, fire alarm
systems, and systems less than 120
volts, nominal.
Secondary circuits of transformerpowered communications or signaling
systems shall not be required to be
enclosed in raceways unless otherwise
specified by Chapter 7 or 8.
[99:4.4.2.2.4.6]
VII. Isolated Power Systems
517.160 Isolated Power Systems.
(A) Installations.
517.160 Isolated Power Systems.
(A) Installations.
(1) Isolated Power Circuits. Each
isolated power circuit shall be
controlled by a switch that has a
disconnecting pole in each isolated
circuit conductor to simultaneously
disconnect all power. Such isolation
shall be accomplished by means of
one or more transformers having no
electrical connection between primary
and secondary windings, by means of
(1) Isolated Power Circuits. Each
isolated power circuit shall be
controlled by a switch that has a
disconnecting pole in each isolated
circuit conductor to simultaneously
disconnect all power. Such isolation
shall be accomplished by means of
one or more isolation transformers, by
means of generator sets, or by means
of electrically isolated batteries.
Page 277 of 361
Change Description and Impact to
Worker Safety
systems need not be installed in a
raceway unless otherwise required by
the Code.
As Safe or Safer.
Clarified that the transformers are
required to be the isolation type and
batteries are required to be electrically
isolated.
As Safe or Safer.
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motor generator sets, or by means of
suitably isolated batteries.
517.160 Isolated Power Systems.
517.160 Isolated Power Systems.
(A) Installations.
(A) Installations.
(5) Conductor Identification. The
isolated circuit conductors shall be
identified as follows:
(5) Conductor Identification. The
isolated circuit conductors shall be
identified as follows:
(1) Isolated Conductor No. 1 —
Orange
(2) Isolated Conductor No. 2 —
Brown
For 3-phase systems, the third
conductor shall be identified as yellow.
Where isolated circuit conductors
supply 125-volt, single-phase, 15- and
20-ampere receptacles, the orange
conductor(s) shall be connected to the
terminal(s) on the receptacles that are
identified in accordance with 200.10(B)
for connection to the grounded circuit
conductor.
(1) Isolated Conductor No. 1 —
Orange with a distinctive colored
stripe other than white, green, or
gray
(2) Isolated Conductor No. 2 —
Brown with a distinctive colored
stripe other than white, green, or
gray
For 3-phase systems, the third
conductor shall be identified as yellow
with a distinctive colored stripe other
than white, green, or gray. Where
isolated circuit conductors supply 125volt, single-phase, 15- and 20-ampere
receptacles, the striped orange
conductor(s) shall be connected to the
terminal(s) on the receptacles that are
identified in accordance with 200.10(B)
for connection to the grounded circuit
conductor.
Page 278 of 361
Change Description and Impact to
Worker Safety
Added requirement that conductors
have a distinctive colored stripe to
distinguish them from other systems
using similar colored conductors.
As Safe or Safer.
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Assembly Occupancies
Article 518
Assembly Occupancies
518.4 Wiring Methods.
518.4 Wiring Methods.
(A) General. The fixed wiring methods
shall be metal raceways, flexible metal
raceways, nonmetallic raceways
encased in not less than 50 mm (2 in.)
of concrete, Type MI, MC, or AC cable
containing an insulated equipment
grounding conductor sized in
accordance with Table 250.122.
(A) General. The fixed wiring methods
shall be metal raceways, flexible metal
raceways, nonmetallic raceways
encased in not less than 50 mm (2 in.)
of concrete, Type MI, MC, or AC cable.
The wiring method shall itself qualify as
an equipment grounding conductor
according to 250.118 or shall contain
an insulated equipment grounding
conductor sized in accordance with
Table 250.122.
518.5 Supply. Portable switchboards
518.5 Supply. Portable switchboards
and portable power distribution
and portable power distribution
equipment shall be supplied only from
equipment shall be supplied only from
listed power outlets of sufficient voltage listed power outlets of sufficient voltage
and ampere rating. Such power outlets and ampere rating. Such power outlets
shall be protected by overcurrent
shall be protected by overcurrent
devices. Such overcurrent devices and devices. Such overcurrent devices and
power outlets shall not be accessible to power outlets shall not be accessible to
the general public. Provisions for
the general public. Provisions for
connection of an equipment grounding connection of an equipment grounding
conductor shall be provided. The
conductor shall be provided. The
neutral of feeders supplying solid-state, neutral conductor of feeders supplying
3-phase, 4-wire dimmer systems shall
solid-state phase control, 3-phase, 4be considered a current-carrying
wire dimmer systems shall be
conductor.
considered a current-carrying
Page 279 of 361
Change Description and Impact to
Worker Safety
Revised to specify that the wiring
method must be an equipment
grounding conductor per 250.118.
As Safe or Safer.
Revised to specify that neutral
conductors of solid-state sine-wave, 3phase 4-wire, dimming systems are
not considered to be current-carrying
conductors for the purpose of ampacity
adjustment.
Added exception to specify that neutral
conductors of feeders supplying both
phase-control and sine-wave dimmers
are current-carrying for ampacity
adjustment purposes.
As Safe or Safer.
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Change Description and Impact to
Worker Safety
conductor for purposes of derating.
The neutral conductor of feeders
supplying solid-state sine wave, 3phase, 4-wire dimming systems shall
not be considered a current-carrying
conductor for purposes of derating.
Exception: The neutral conductor of
feeders supplying systems that use or
may use both phase-control and sinewave dimmers shall be considered as
current-carrying for purposes of
derating.
NOTE: Articles 520 through 555 are determined to have minimal application at the Idaho site and will not be
addressed.
Article 590
Temporary Installations
Temporary Installations
Revised to reference applicable parts
of Article 230 that apply to temporary
590.4 General.
590.4 General.
installations.
(A) Services. Services shall be
(A) Services. Services shall be
installed in conformance with Article
installed in conformance with Parts I
As Safe or Safer.
230.
through VIII of Article 230, as
applicable.
590.4 General.
590.4 General.
Clarified that a metal raceway or cable
(D) Receptacles. All receptacles shall
(D) Receptacles. All receptacles shall
that is not continuous or does not
be of the grounding type. Unless
be of the grounding type. Unless
qualify as an equipment grounding
installed in a continuous grounded
installed in a continuous metal raceway conductor in accordance with 250.118
metal raceway or metal-covered cable, that qualifies as an equipment
must contain a separate wire-type
all branch circuits shall contain a
grounding conductor in accordance
equipment grounding conductor.
separate equipment grounding
with 250.118 or a continuous metalconductor, and all receptacles shall be covered cable that qualifies as an
Actually may improve electrical safety
Page 280 of 361
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electrically connected to the equipment
grounding conductors. Receptacles on
construction sites shall not be installed
on branch circuits that supply
temporary lighting. Receptacles shall
not be connected to the same
ungrounded conductor of multiwire
circuits that supply temporary lighting.
equipment grounding conductor in
accordance with 250.118, all branch
circuits shall include a separate
equipment grounding conductor, and
all receptacles shall be electrically
connected to the equipment grounding
conductor(s). Receptacles on
construction sites shall not be installed
on branch circuits that supply
temporary lighting. Receptacles shall
not be connected to the same
ungrounded conductor of multiwire
circuits that supply temporary lighting.
590.4 General.
(E) Disconnecting Means. Suitable
disconnecting switches or plug
connectors shall be installed to permit
the disconnection of all ungrounded
conductors of each temporary circuit.
Multiwire branch circuits shall be
provided with a means to disconnect
simultaneously all ungrounded
conductors at the power outlet or
panelboard where the branch circuit
originated. Identified handle ties shall
be permitted.
590.6 Ground-Fault Protection for
Personnel. Ground-fault protection for
personnel for all temporary wiring
installations shall be provided to
comply with 590.6(A) and (B). This
590.4 General.
(E) Disconnecting Means. Suitable
disconnecting switches or plug
connectors shall be installed to permit
the disconnection of all ungrounded
conductors of each temporary circuit.
Multiwire branch circuits shall be
provided with a means to disconnect
simultaneously all ungrounded
conductors at the power outlet or
panelboard where the branch circuit
originated. Approved handle ties shall
be permitted.
590.6 Ground-Fault Protection for
Personnel. Ground-fault protection for
personnel for all temporary wiring
installations shall be provided to
comply with 590.6(A) and 590.6(B).
Page 281 of 361
Change Description and Impact to
Worker Safety
for the worker.
Revised to specify that only identified
handle ties are permitted.
As Safe or Safer.
Revised to specify that ground-fault
protection for personnel (GFCI)
requirements apply to temporary
installations supplied by electric utility
or on-site generated power.
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This section shall apply only to
temporary wiring installations used to
supply temporary power to equipment
used by personnel during construction,
remodeling, maintenance, repair, or
demolition of buildings, structures,
equipment, or similar activities.
Change Description and Impact to
Worker Safety
section shall apply only to temporary
wiring installations used to supply
temporary power to equipment used by
personnel during construction,
remodeling, maintenance, repair, or
demolition of buildings, structures,
equipment, or similar activities. This
section shall apply to power derived
from an electric utility company or from
an on-site-generated power source.
NOTE: Article 600 is determined to have minimal application at the Idaho site and will not be addressed.
Article 604
Manufactured Wiring Systems
Manufactured Wiring Systems
Revised definition to describe types of
equipment connected to manufactured
604.2 Definition.
604.2 Definition.
wiring systems.
Manufactured Wiring System. A
Manufactured Wiring System. A
system containing component parts
system containing component parts
As Safe or Safer.
that are assembled in the process of
that are assembled in the process of
manufacture and cannot be inspected
manufacture and cannot be inspected
at the building site without damage or
at the building site without damage or
destruction to the assembly.
destruction to the assembly and used
for the connection of luminaires,
utilization equipment, continuous plugin type busways, and other devices.
604.6 Construction.
604.6 Construction.
Added Type MC cable with a
combined bore grounding conductor
(A) Cable or Conduit Types.
(A) Cable or Conduit Types.
and metal armor as the equipment
grounding conductor to the list of
(1) Cables. Cable shall be listed Type
(1) Cables. Cable shall be one of the
acceptable cable wiring methods.
AC cable or listed Type MC cable
following:
containing nominal 600-volt, 8 to 12
(1) Listed Type AC cable containing As Safe or Safer.
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AWG insulated copper conductors with
a bare or insulated copper equipment
grounding conductor equivalent in size
to the ungrounded conductor.
2008 NEC
Change Description and Impact to
Worker Safety
nominal 600-volt, 8 to 12 AWG
insulated copper conductors with a
bare or insulated copper equipment
grounding conductor equivalent in
size to the ungrounded conductor.
(2) Listed Type MC cable containing
nominal 600-volt, 8 to 12 AWG
insulated copper conductors with a
bare or insulated copper equipment
grounding conductor equivalent in
size to the ungrounded conductor.
604.6 Construction.
(3) Listed Type MC cable containing
nominal 600-volt, 8 to 12 AWG
insulated copper conductors with a
grounding conductor and armor
assembly listed and identified for
grounding in accordance with
250.118(10). The combined metallic
sheath and grounding conductor
shall have a current-carrying
capacity equivalent to that of the
ungrounded copper conductor.
604.6 Construction.
(A) Cable or Conduit Types.
(A) Cable or Conduit Types.
(3) Flexible Cord.
(3) Flexible Cord.
Added exception permitting listed
electric discharge luminaires with
conductors smaller than 12 AWG for
use in accordance with 410.62(C)
As Safe or Safer.
Exception: Listed electric-discharge
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604.6 Construction.
luminaires that comply with 410.62(C)
shall be permitted with conductors
smaller than 12 AWG.
604.6 Construction.
(A) Cable or Conduit Types.
(A) Cable or Conduit Types.
Change Description and Impact to
Worker Safety
Added new section to address
busways.
As Safe or Safer.
604.6 Construction.
(C) Receptacles and Connectors.
Receptacles and connectors shall be
of the locking type, uniquely polarized
and identified for the purpose, and
shall be part of a listed assembly for
the appropriate system.
(4) Busways. Busways shall be listed
continuous plug-in type containing
factory mounted, bare or insulated
conductors, which shall be copper or
aluminum bars, rods, or tubes. The
busway shall be grounded and
provided with an equipment ground
busbar equivalent in size to the
ungrounded busbar. The busway shall
be rated nominal 600 volts, 20, 30, or
40 amperes. Busways shall be
installed in accordance with 368.12,
368.17(D) and 368.30.
604.6 Construction.
(C) Receptacles and Connectors.
Receptacles and connectors shall be
of the locking type, uniquely polarized
and identified for the purpose, and
shall be part of a listed assembly for
the appropriate system. All connector
openings shall be designed to prevent
inadvertent contact with live parts or
capped to effectively close the
Page 284 of 361
Revised to require all connector
openings to be designed to prevent
inadvertent contact with live parts or to
be capped so as to effectively close
the connector opening.
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604.6 Construction.
(E) Securing and Supporting.
Manufactured wiring systems shall be
secured and supported in accordance
with the applicable cable or conduit
article for the cable or conduit type
employed.
2008 NEC
connector openings.
604.7 Installation. Manufactured wiring
systems shall be secured and
supported in accordance with the
applicable cable or conduit article for
the cable or conduit type employed.
Change Description and Impact to
Worker Safety
Renumbered and renamed 604.6(E)
and deleted 604.6(F) and original
604.7.
As Safe or Safer.

(F) Luminaires (Fixtures). Installation of
listed electric discharge luminaires
(fixtures) complying with 410.30(C)
shall be permitted.
604.7 Unused Outlets. All unused
outlets shall be capped to effectively
close the connector openings.
Cranes and Hoists
III. Contact Conductors
Article 605 had no substantial changes.
Article 610
Cranes and Hoists
Continued emphasis on connection to
an equipment grounding conductor
III. Contact Conductors
versus just grounding.
610.21 Installation of Contact
Conductors.
610.21 Installation of Contact
Conductors.
(F) Track as Circuit Conductor.
(F) Track as Circuit Conductor.
(4) The rail serving as a conductor is
(4) The rail serving as a conductor
Page 285 of 361
As Safe or Safer.
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effectively grounded at the transformer
and also shall be permitted to be
grounded by the fittings used for the
suspension or attachment of the rail to
a building or structure.
IV. Disconnecting Means
shall be bonded to the equipment
grounding conductor at the transformer
and also shall be permitted to be
grounded by the fittings used for the
suspension or attachment of the rail to
a building or structure.
IV. Disconnecting Means
610.31 Runway Conductor
Disconnecting Means.
610.31 Runway Conductor
Disconnecting Means.
Change Description and Impact to
Worker Safety
Added requirement on the type of
locking provision to be provided as part
of the installed equipment.
As Safe or Safer.
(2) Capable of being locked in the
open position
610.32 Disconnecting Means for
Cranes and Monorail Hoists. A motorcircuit switch, molded-case switch, or
circuit breaker shall be provided in the
leads from the runway contact
conductors or other power supply on
all cranes and monorail hoists. The
disconnecting means shall be capable
(2) Capable of being locked in the
open position. The provision for locking
or adding a lock to the disconnecting
means shall be installed on or at the
switch or circuit breaker used as the
disconnecting means and shall remain
in place with or without the lock
installed. Portable means for adding a
lock to the switch or circuit breaker
shall not be permitted as the means
required to be installed at and remain
with the equipment.
610.32 Disconnecting Means for
Cranes and Monorail Hoists. A motorcircuit switch, molded-case switch, or
circuit breaker shall be provided in the
leads from the runway contact
conductors or other power supply on
all cranes and monorail hoists. The
disconnecting means shall be capable
Page 286 of 361
Added requirement on the type of
locking provision to be provided as part
of the installed equipment.
As Safe or Safer.
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of being locked in the open position.
VII. Grounding
610.61 Grounding. All exposed non–
current-carrying metal parts of cranes,
monorail hoists, hoists, and
accessories, including pendant
controls, shall be metallically joined
together into a continuous electrical
conductor so that the entire crane or
hoist will be grounded in accordance
with Article 250.
620.2 Definitions.
2008 NEC
of being locked in the open position.
The provision for locking or adding a
lock to the disconnecting means shall
be installed on or at the switch or
circuit breaker used as the
disconnecting means and shall remain
in place with or without the lock
installed. Portable means for adding a
lock to the switch or circuit breaker
shall not be permitted.
VII. Grounding
610.61 Grounding. All exposed non–
current-carrying metal parts of cranes,
monorail hoists, hoists, and
accessories, including pendant
controls, shall be bonded either by
mechanical connections or bonding
jumpers, where applicable, so that the
entire crane or hoist is a ground-fault
current path as required or permitted
by Article 250, Parts V and VII.
Article 620
Elevators, Dumbwaiters, Escalators,
Moving Walks, Platform Lifts, and
Stairway Chairlifts
620.2 Definitions.
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Modified to provide specific grounding
and bonding requirements.
As Safe or Safer.
Replaced wheel chair lift with platform
lift throughout the article for correlation
with ASME A18.1, Safety Standard on
Platform Lifts and Wheelchair Lifts.
As Safe or Safer.
Added definitions for remote machine
room and control room and remote
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Remote Machine Room and Control
Room (for Elevator, Dumbwaiter). A
machine room or control room that is
not attached to the outside perimeter
or surface of the walls, ceiling, or floor
of the hoistway.
620.3 Voltage Limitations.
Remote Machinery Space and Control
Space (for Elevator, Dumbwaiter). A
machinery space or control space that
is not within the hoistway, machine
room, or control room and that is not
attached to the outside perimeter or
surface of the walls, ceiling, or floor of
the hoistway.
620.3 Voltage Limitations.
(A) Power Circuits. Branch circuits to
door operator controllers and door
motors and branch circuits and feeders
to motor controllers, driving machine
motors, machine brakes, and motorgenerator sets shall not have a circuit
voltage in excess of 600 volts. Internal
voltages of power conversion and
functionally associated equipment,
including the interconnecting wiring,
shall be permitted to have higher
voltages, provided that all such
equipment and wiring shall be listed for
the higher voltages. Where the voltage
(A) Power Circuits. Branch circuits to
door operator controllers and door
motors and branch circuits and feeders
to motor controllers, driving machine
motors, machine brakes, and motorgenerator sets shall not have a circuit
voltage in excess of 600 volts. Internal
voltages of power conversion
equipment and functionally associated
equipment, and the operating voltages
of wiring interconnecting the
equipment, shall be permitted to be
higher, provided that all such
equipment and wiring shall be listed for
Page 288 of 361
Change Description and Impact to
Worker Safety
machinery space and control space.
As Safe or Safer.
Clarified that both the internal voltages
of power conversion equipment and
the operating voltages of wiring
interconnecting the equipment are
permitted to exceed 600 volts.
As Safe or Safer.
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exceeds 600 volts, warning labels or
signs that read “DANGER — HIGH
VOLTAGE” shall be attached to the
equipment and shall be plainly visible.
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Change Description and Impact to
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III. Wiring
the higher voltages. Where the voltage
exceeds 600 volts, warning labels or
signs that read “DANGER — HIGH
VOLTAGE” shall be attached to the
equipment and shall be plainly visible.
III. Wiring
620.21 Wiring Methods.
620.21 Wiring Methods.
Added section to permit cordconnected sump and oil recovery
pumps in elevator pits.
(A) Elevators.
(A) Elevators.
As Safe or Safer.
(1) Hoistways.
(1) Hoistways.

(d) The following wiring methods shall
be permitted in the hoistway in lengths
not to exceed 1.8 m (6 ft):
(1) Flexible metal conduit
(2) Liquidtight flexible metal conduit
(3) Liquidtight flexible nonmetallic
conduit
(4) Flexible cords and cables, or
conductors grouped together and
taped or corded, shall be permitted to
be installed without a raceway. They
shall be located to be protected from
physical damage and shall be of a
flame-retardant type and shall be part
of the following:
a. Listed equipment
b. A driving machine, or
c. A driving machine brake
(d) Flexible metal conduit, liquidtight
flexible metal conduit, liquidtight
flexible nonmetallic conduit or flexible
cords and cables, or conductors
grouped together and taped or corded
that are part of listed equipment, a
driving machine, or a driving machine
brake shall be permitted in the
hoistway, in lengths not to exceed 1.8
m (6 ft), without being installed in a
raceway and where located to be
protected from physical damage and
are of a flame-retardant type.
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620.21 Wiring Methods.
(e) A sump pump or oil recovery pump
located in the pit shall be permitted to
be cord connected. The cord shall be a
hard usage oil-resistant type, of a
length not to exceed 1.8 m (6 ft), and
shall be located to be protected from
physical damage.
620.21 Wiring Methods.
(C) Platform Lifts and Stairway Chairlift
Raceways.
(C) Platform Lifts and Stairway Chairlift
Raceways.
620.23 Branch Circuits for Machine
Room or Control Room/Machinery
Space or Control Space Lighting and
Receptacle(s).
(3) Flexible Cords and Cables. Flexible
cords and cables that are components
of listed equipment and used in circuits
operating at 30 volts rms or less or 42
volts dc or less shall be permitted in
lengths not to exceed 1.8 m (6 ft),
provided the cords and cables are
supported and protected from physical
damage and are of a jacketed and
flame retardant type.
620.23 Branch Circuits for Machine
Room or Control Room/Machinery
Space or Control Space Lighting and
Receptacle(s).
(C) Duplex Receptacle. At least one
125-volt, single-phase, duplex
receptacle shall be provided in each
(C) Duplex Receptacle. At least one
125-volt, single-phase, 15- or 20ampere duplex receptacle shall be
Page 290 of 361
Change Description and Impact to
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Added section to permit the use of
limited lengths of flame-retardant
flexible cord and cable for limitedenergy circuits associated with
platform lifts and stairway chairlifts.
As Safe or Safer.
Specified that the required receptacle
must be rated 15 or 20 amperes.
As Safe or Safer.
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machine room or control room and
machinery space or control space.
620.24 Branch Circuit for Hoistway Pit
Lighting and Receptacle(s).
(C) Duplex Receptacle. At least one
125-volt, single-phase, duplex
receptacle shall be provided in the
hoistway pit.
620.44 Installation of Traveling Cables.
Traveling cable shall be permitted to
be run without the use of a raceway
for a distance not exceeding 1.8 m (6
ft) in length as measured from the first
point of support on the elevator car or
hoistway wall, or counterweight where
applicable, provided the conductors
are grouped together and taped or
corded, or in the original sheath.
Traveling cables shall be permitted to
be continued as fixed wiring to elevator
controller enclosures and to elevator
car and machine room, control room,
machinery space, and control space
connections, provided they are suitably
supported and protected from physical
damage.
2008 NEC
provided in each machine room or
control room and machinery space or
control space.
620.24 Branch Circuit for Hoistway Pit
Lighting and Receptacle(s).
(C) Duplex Receptacle. At least one
125-volt, single-phase, 15- or 20ampere duplex receptacle shall be
provided in the hoistway pit.
620.44 Installation of Traveling Cables.
Traveling cables that are suitably
supported and protected from physical
damage shall be permitted to be run
without the use of a raceway in either
or both of the following:
(a) When used inside the hoistway, on
the elevator car, hoistway wall,
counterweight, or controllers and
machinery that are located inside the
hoistway, provided the cables are in
the original sheath.
(b) From inside the hoistway, to
elevator controller enclosures and to
elevator car and machine room, control
room, machinery space, and control
space connections that are located
outside the hoistway for a distance not
exceeding 1.8 m (6 ft) in length as
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Change Description and Impact to
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Specified that the required receptacle
must be rated 15 or 20 amperes.
As Safe or Safer.
Revised to permit lengths of traveling
cable exceeding 6 ft inside the
hoistway without having to be installed
in a raceway.
As Safe or Safer.
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Change Description and Impact to
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measured from the first point of
support on the elevator car or hoistway
wall, or counterweight where
applicable, provided the conductors
are grouped together and taped or
corded, or in the original sheath. These
traveling cables shall be permitted to
be continued to this equipment.
VI. Disconnecting Means and Control
VI. Disconnecting Means and Control
• Article 620, Part VI Disconnecting
Means and Control: Revised several
620.51 Disconnecting Means.
620.51 Disconnecting Means.
requirements on the type of locking
provision to be provided as part of the
(A) Type. The disconnecting means
(A) Type. The disconnecting means
installed equipment.
shall be an enclosed externally
shall be an enclosed externally
operable fused motor circuit switch or
operable fused motor circuit switch or
(Sections 620.53, 620.54 and 620.55
circuit breaker capable of being locked circuit breaker capable of being locked have similar wording insertions.)
in the open position. The disconnecting in the open position. The provision for
means shall be a listed device.
locking or adding a lock to the
As Safe or Safer.
disconnecting means shall be installed
on or at the switch or circuit breaker
used as the disconnecting means and
shall remain in place with or without
the lock installed. Portable means for
adding a lock to the switch or circuit
breaker shall not be permitted as the
means required to be installed at and
remain with the equipment.
620.51 Disconnecting Means.
The disconnecting means shall be a
listed device.
620.51 Disconnecting Means.
Page 292 of 361
Revised to cover motor controllers
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installed in hoistways by requiring the
(C) Location. The disconnecting means (C) Location. The disconnecting means main power disconnecting means to be
shall be located where it is readily
shall be located where it is readily
located outside the hoistway (in a
accessible to qualified persons.
accessible to qualified persons.
machine room or space or control
room or space) and an additional non(1) On Elevators Without Generator
(1) On Elevators Without Generator
fused disconnecting means to be
Field Control. On elevators without
Field Control. On elevators without
installed within sight of the motor
generator field control, the
generator field control, the
controller in the elevator hoistway.
disconnecting means shall be located
disconnecting means shall be located
within sight of the motor controller.
within sight of the motor controller.
As Safe or Safer.
Driving machines or motion and
Where the motor controller is located in
operation controllers not within sight of the elevator hoistway, the
the disconnecting means shall be
disconnecting means required by
provided with a manually operated
620.51(A) shall be located in a
switch installed in the control circuit to
machinery space, machine room,
prevent starting. The manually
control space or control room outside
operated switch(es) shall be installed
the hoistway; and an additional, nonadjacent to this equipment.
fused enclosed externally operable
motor circuit switch capable of being
Where the driving machine of an
locked in the open position to
electric elevator or the hydraulic
disconnect all ungrounded main
machine of a hydraulic elevator is
power-supply conductors shall be
located in a remote machine room or
located within sight of the motor
remote machinery space, a single
controller. The additional switch shall
means for disconnecting all
be a listed device and shall comply
ungrounded main power supply
with 620.91(C).
conductors shall be provided and be
capable of being locked in the open
The provision for locking or adding a
position.
lock to the disconnecting means,
required by this section, shall be
installed on or at the switch or circuit
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IX. Grounding
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breaker used as the disconnecting
means and shall remain in place with
or without the lock installed. Portable
means for adding a lock to the switch
or circuit breaker shall not be
permitted.
IX. Grounding
620.81 Metal Raceways Attached to
Cars. Metal raceways, Type MC cable,
Type MI cable, or Type AC cable
attached to elevator cars shall be
bonded to grounded metal parts of the
car that they contact.
620.81 Metal Raceways Attached to
Cars. Metal raceways, Type MC cable,
Type MI cable, or Type AC cable
attached to elevator cars shall be
bonded to metal parts of the car that
are bonded to the equipment
grounding conductor.
620.82 Electric Elevators. For electric
elevators, the frames of all motors,
elevator machines, controllers, and the
metal enclosures for all electrical
equipment in or on the car or in the
hoistway shall be grounded in
accordance with Article 250.
620.82 Electric Elevators. For electric
elevators, the frames of all motors,
elevator machines, controllers, and the
metal enclosures for all electrical
equipment in or on the car or in the
hoistway shall be bonded in
accordance with Article 250, Parts V
and VII.
620.83 Nonelectric Elevators. For
elevators other than electric having any
electric conductors attached to the car,
the metal frame of the car, where
normally accessible to persons, shall
be grounded in accordance with Article
620.83 Nonelectric Elevators. For
elevators other than electric having any
electrical conductors attached to the
car, the metal frame of the car, where
normally accessible to persons, shall
be bonded in accordance with Article
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Change Description and Impact to
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Revised several sections to address
specific bonding requirements and the
connection to the equipment grounding
conductor.
May actually improve safety.
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Change Description and Impact to
Worker Safety
250.
250, Parts V and VII.
NOTE: Articles 625, 626 and 630 did not have substantial revisions.
Article 640
Audio Signal Processing, Amplification, Audio Signal Processing, Amplification, Changed to specifically state that
and Reproduction Equipment
and Reproduction Equipment
Section 300.21 applies to Article 640 to
eliminate the confusion and
640.3 Locations and Other Articles.
640.3 Locations and Other Articles.
controversy surrounding applicability of
Circuits and equipment shall comply
Circuits and equipment shall comply
the wiring method section.
with 640.3(A) through 640.3(L), as
with 640.3(A) through (L), as
applicable.
applicable.
As Safe or Safer.
(A) Spread of Fire or Products of
Combustion. The accessible portion of
abandoned audio distribution cables
shall be removed. See 300.21.
640.6 Mechanical Execution of Work.
(A) Spread of Fire or Products of
Combustion. Section 300.21 shall
apply.
Equipment and cables shall be
installed in a neat workmanlike
manner. Cables installed exposed on
the surface of ceilings and sidewalls
shall be supported in such a manner
that the cables will not be damaged by
normal building use. Such cables shall
be supported by straps, staples,
hangers, or similar fittings designed
and installed so as not to damage the
cable. The installation shall conform to
300.4(D) and 300.11.
(A) Neat and Workmanlike Manner.
Audio signal processing, amplification,
and reproduction equipment, cables,
and circuits shall be installed in a neat
workmanlike manner.
640.6 Mechanical Execution of Work.
(B) Installation of Audio Distribution
Cables. Cables installed exposed on
the surface of ceilings and sidewalls
shall be supported in such a manner
that the audio distribution cables will
not be damaged by normal building
use. Such cables shall be secured by
straps, staples, cable ties, hangers, or
Page 295 of 361
Revised to require installations to
comply with all requirements in 300.4
and 300.11(A), to require securing of
audio cables, and to permit cable ties
as a securing means.
Relocated requirement on removing
accessible portions of abandoned
cables.
Added identification requirements for
cables installed for future use.
As Safe or Safer.
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Change Description and Impact to
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similar fittings designed and installed
so as not to damage the cable. The
installation shall conform to 300.4 and
300.11(A).

(C) Abandoned Audio Distribution
Cables. The accessible portion of
abandoned audio distribution cables
shall be removed.
(D) Installed Audio Distribution Cable
Identified for Future Use.
640.7 Grounding.
(A) General. Wireways and auxiliary
gutters shall be grounded and bonded
in accordance with the requirements of
(1) Cables identified for future use shall
be marked with a tag of sufficient
durability to withstand the environment
involved.
(2) Cable tags shall have the following
information:
(1) Date cable was identified for
future use
(2) Date of intended use
(3) Information related to the
intended future use of cable

640.7 Grounding.
Provides specific requirements for
grounding and bonding which
(A) General. Wireways and auxiliary
addresses connection to an equipment
gutters shall be connected to an
grounding conductor.
equipment grounding conductor(s), to
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Article 250. Where the wireway or
auxiliary gutter does not contain
power-supply wires, the equipment
grounding conductor shall not be
required to be larger than 14 AWG
copper or its equivalent. Where the
wireway or auxiliary gutter contains
power-supply wires, the equipment
grounding conductor shall not be
smaller than specified in 250.122.
Information Technology Equipment
2008 NEC
an equipment bonding jumper, or to
the grounded conductor where
permitted or required by 250.92(B)(1)
or 250.142. Where the wireway or
auxiliary gutter does not contain
power-supply wires, the equipment
grounding conductor shall not be
required to be larger than 14 AWG
copper or its equivalent. Where the
wireway or auxiliary gutter contains
power-supply wires, the equipment
grounding conductor shall not be
smaller than specified in 250.122.
Article 645
Information Technology Equipment
Change Description and Impact to
Worker Safety
May actually improve safety.
645.2 Definition.
Added definition of abandoned cables.
As Safe or Safer.
645.5 Supply Circuits and
Interconnecting Cables.
Abandoned Supply Circuits and
Interconnecting Cables. Installed
supply circuits and interconnecting
cables that are not terminated at
equipment and not identified for future
use with a tag.
645.5 Supply Circuits and
Interconnecting Cables.
(D) Under Raised Floors. Power
cables, communications cables,
connecting cables, interconnecting
cables, and receptacles associated
(D) Under Raised Floors. Power
cables, communications cables,
connecting cables, interconnecting
cables, cord-and-plug connections,
Page 297 of 361
Revised to specifically permit flexible
cords in the space below a raised floor
to make a cord-and-plug connection to
a supply receptacle.
As Safe or Safer.
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with the information technology
equipment shall be permitted under a
raised floor, provided the following
conditions are met:
645.5 Supply Circuits and
Interconnecting Cables.
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Change Description and Impact to
Worker Safety
and receptacles associated with the
information technology equipment shall
be permitted under a raised floor,
provided the following conditions are
met:
(3) Supply cords of listed information
technology equipment in accordance
with 645.5(B).
645.5 Supply Circuits and
Interconnecting Cables.
(D)(5) c. Cable type designations Type
TC (Article 336); Types CL2, CL3, and
PLTC (Article 725); Type ITC (Article
727); Types NPLF and FPL (Article
760); Types OFC and OFN (Article
770); Type CM (Article 800); and Type
CATV (Article 820). These
designations shall be permitted to have
an additional letter P or R or G. Green,
or green with one or more yellow
stripes, insulated single conductor
cables, 4 AWG and larger, marked “for
use in cable trays” or “for CT use” shall
be permitted for equipment grounding.
(D)(6) c. Cable type designations
shown in Table 645.5 shall be
permitted. Green, or green with one or
more yellow stripes, insulated singleconductor cables, 4 AWG and larger,
marked “for use in cable trays” or “for
CT use” shall be permitted for
equipment grounding.
(6) Abandoned cables shall be
removed unless contained in metal
raceways.
645.5 Supply Circuits and

645.5 Supply Circuits and
Page 298 of 361
Moved text to new Table 645.5 to
clarify cable types permitted beneath a
raised floor and relocated reference to
abandoned cables to new Section (F).
As Safe or Safer.
Relocated requirement for removal of
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Interconnecting Cables.
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Interconnecting Cables.
(F) Abandoned Supply Circuits and
Interconnecting Cables. The
accessible portion of abandoned
supply circuits and interconnecting
cables shall be removed unless
contained in a metal raceway.
645.5 Supply Circuits and
Interconnecting Cables.
645.5 Supply Circuits and
Interconnecting Cables.
(G) Installed Supply Circuits and
Interconnecting Cables Identified for
Future Use.
(1) Supply circuits and interconnecting
cables identified for future use shall be
marked with a tag of sufficient
durability to withstand the environment
involved.
(2) Supply circuit tags and
interconnecting cable tags shall have
the following information:
a. Date identified for future use
b. Date of intended use
c. Information relating to the
intended future use
645.10 Disconnecting Means. A means 645.10 Disconnecting Means. An
shall be provided to disconnect power
approved means shall be provided to
to all electronic equipment in the
disconnect power to all electronic
information technology equipment
equipment in the information
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Change Description and Impact to
Worker Safety
accessible portions of abandoned
cables.
As Safe or Safer.
Added identification requirements for
cables installed for future use.
As Safe or Safer.
Revised to require approval of the
disconnecting means and allow for
shutdown of designated zones within
IT rooms.
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room. There shall also be a similar
means to disconnect the power to all
dedicated HVAC systems serving the
room and cause all required fire/smoke
dampers to close. The control for these
disconnecting means shall be grouped
and identified and shall be readily
accessible at the principal exit doors. A
single means to control both the
electronic equipment and HVAC
systems shall be permitted. Where a
pushbutton is used as a means to
disconnect power, pushing the button
in shall disconnect the power.
technology equipment room or in
designated zones within the room.
There shall also be a similar approved
means to disconnect the power to all
dedicated HVAC systems serving the
room or designated zones and shall
cause all required fire/smoke dampers
to close. The control for these
disconnecting means shall be grouped
and identified and shall be readily
accessible at the principal exit doors. A
single means to control both the
electronic equipment and HVAC
systems in the room or in a zone shall
be permitted. Where a pushbutton is
used as a means to disconnect power,
pushing the button in shall disconnect
the power. Where multiple zones are
created, each zone shall have an
approved means to confine fire or
products of combustion to within the
zone.
Article 647
Sensitive Electronic Equipment
(C) Color Coding. All feeders and
branch-circuit conductors installed
under this section shall be identified as
to system at all splices and
terminations by color, marking,
tagging, or equally effective means.
(C) Conductor Identification. All
feeders and branch-circuit conductors
installed under this section shall be
identified as to system at all splices
and terminations by color, marking,
tagging, or equally effective means.
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Change Description and Impact to
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As Safe or Safer.
Revised title to correlate with text of
the section permitting other than color
coding as a means of conductor
identification.
As Safe or Safer.
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The means of identification shall be
posted at each branch-circuit
panelboard and at the disconnecting
means for the building.
647.8 Lighting Equipment.
The means of identification shall be
posted at each branch-circuit
panelboard and at the disconnecting
means for the building.
647.8 Lighting Equipment.
(A) Disconnecting Means. All
luminaires (lighting fixtures) connected
to separately derived systems
operating at 60 volts to ground, and
associated control equipment if
provided, shall have a disconnecting
means that simultaneously opens all
ungrounded conductors. The
disconnecting means shall be located
within sight of the luminaire (lighting
fixture) or be capable of being locked
in the open position.
(A) Disconnecting Means. All
luminaires connected to separately
derived systems operating at 60 volts
to ground, and associated control
equipment if provided, shall have a
disconnecting means that
simultaneously opens all ungrounded
conductors. The disconnecting means
shall be located within sight of the
luminaire or be capable of being locked
in the open position. The provision for
locking or adding a lock to the
disconnecting means shall be installed
on or at the switch or circuit breaker
used as the disconnecting means and
shall remain in place with or without
the lock installed. Portable means for
adding a lock to the switch or circuit
breaker shall not be permitted.
Article 665
Induction and Dielectric Heating
Equipment
The provision for locking or adding a
lock to the disconnecting means shall
be installed on or at the switch or
Page 301 of 361
Change Description and Impact to
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Added requirement on the type of
locking equipment to be provided as
part of the installed equipment.
As Safe or Safer.
665.12, 665.22: Added requirement on
the type of locking provision to be
provided as part of the installed
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Change Description and Impact to
Worker Safety
equipment.
circuit breaker used as the
disconnecting means and shall remain
in place with or without the lock
As Safe or Safer.
installed. Portable means for adding a
lock to the switch or circuit breaker
shall not be permitted.
665.26 Grounding and Bonding.
665.26 Grounding and Bonding.
Continuing the emphasis on
Grounding or inter-unit bonding, or
Bonding to the equipment grounding
connection to the equipment grounding
both, shall be used wherever required
conductor or inter-unit bonding, or
conductor versus grounding.
for circuit operation, for limiting to a
both, shall be used wherever required
safe value radio frequency voltages
for circuit operation, and for limiting to
As Safe or Safer.
between all exposed non–currenta safe value radio frequency voltages
carrying parts of the equipment and
between all exposed non–currentearth ground, between all equipment
carrying parts of the equipment
parts and surrounding objects, and
and earth ground, between all
between such objects and earth
equipment parts and surrounding
ground. Such grounding and bonding
objects, and between such objects and
shall be installed in accordance with
earth ground. Such connection to the
Article 250, Parts II and V.
equipment grounding conductor and
bonding shall be installed in
accordance with Article 250, Parts II
and V.
NOTE: Articles 667 through 692 are determined to have minimal applicability at the Idaho site and are not
included.
Article 695
Fire Pumps
695.4 Continuity of Power.
695.4 Continuity of Power.
Added requirement that conductors
supplied by an on-site standby
(A) Direct Connection. The supply
(A) Direct Connection. The supply
generator(s) connect to a separate
conductors shall directly connect the
conductors shall directly connect the
disconnecting means dedicated to the
power source to either a listed fire
power source to either a listed fire
fire pump.
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pump controller or listed combination
fire pump controller and power transfer
switch.
pump controller or listed combination
fire pump controller and power transfer
switch. Where the power source is
supplied by on-site generator(s), the
supply conductors shall connect to a
generator disconnecting means
dedicated for the purposes of serving
the fire pump. The disconnecting
means shall be located in a separate
enclosure from the other generator
disconnecting means.
(1) Overcurrent Device Selection. The
overcurrent protective device(s) shall
be selected or set to carry indefinitely
the sum of the locked-rotor current of
the fire pump motor(s) and the
pressure maintenance pump motor(s)
and the full-load current of the
associated fire pump accessory
equipment when connected to this
power supply. The next standard
overcurrent device shall be used in
accordance with 240.6. The
requirement to carry the locked-rotor
currents indefinitely shall not apply to
conductors or devices other than
overcurrent devices in the fire pump
motor circuit(s).
Article 700
Emergency Systems
Emergency Systems
Page 303 of 361
Change Description and Impact to
Worker Safety
As Safe or Safer.
Added provision to limit size of
overcurrent protective device to the
next standard size or rating specified in
240.6.
As Safe or Safer.
Revised to require that automatic
transfer switches rated 600 volts and
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700.6 Transfer Equipment.
700.6 Transfer Equipment.
(C) Automatic Transfer Switches.
Automatic transfer switches shall be
electrically operated and mechanically
held.
II. Circuit Wiring
(C) Automatic Transfer Switches.
Automatic transfer switches shall be
electrically operated and mechanically
held. Automatic transfer switches,
rated 600 VAC and below, shall be
listed for emergency system use.
II. Circuit Wiring
700.9 Wiring, Emergency System.
700.9 Wiring, Emergency System.
(B) Wiring.
(B) Wiring.
Change Description and Impact to
Worker Safety
below be listed for use with emergency
systems.
As Safe or Safer.
Added wiring separation provisions for
emergency sources supplying
combinations of emergency, legally
required, or optional loads.
As Safe or Safer.
(5) Wiring from an emergency source
to supply any combination of
emergency, legally required, or
optional loads in accordance with (a),
(b), and (c):
a. From separate vertical
switchboard sections, with or
without a common bus, or from
individual disconnects mounted in
separate enclosures.
b. The common bus or separate
sections of the switchboard or the
individual enclosures shall be
permitted to be supplied by single or
multiple feeders without overcurrent
Page 304 of 361
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Change Description and Impact to
Worker Safety
protection at the source.
Exception to (5)(b): Overcurrent
protection shall be permitted at the
source or for the equipment, provided
the overcurrent protection is selectively
coordinated with the downstream
overcurrent protection.
II. Circuit Wiring
c. Legally required and optional
standby circuits shall not originate
from the same vertical switchboard
section, panelboard enclosure, or
individual disconnect enclosure as
emergency circuits.
II. Circuit Wiring
700.9 Wiring, Emergency System.
700.9 Wiring, Emergency System.
(D) Fire Protection.
(1) Feeder-Circuit Wiring.
(4) Be protected by a fire-rated
assembly listed to achieve a
minimum fire rating of 1 hour
700.9 Wiring, Emergency System.
(D) Fire Protection.
(1) Feeder-Circuit Wiring.
(4) Be protected by a listed firerated assembly that has a minimum
fire rating of 1-hour and contains
only emergency wiring circuits.
700.9 Wiring, Emergency System.
(D) Fire Protection.
(D) Fire Protection.
(3) Generator Control Wiring. Control
conductors installed between the
Page 305 of 361
Revised to require that fire-rated
assemblies protecting emergency
circuits contain only emergency wiring.
As Safe or Safer.
Added requirement for the separation
and protection of generator control
wiring.
As Safe or Safer.
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Change Description and Impact to
Worker Safety
III. Sources of Power
transfer equipment and the emergency
generator shall be kept entirely
independent of all other wiring and
shall meet the conditions of
700.9(D)(1).
III. Sources of Power
700.12 General Requirements.
(B) Generator Set.
700.12 General Requirements.
(B) Generator Set.
As Safe or Safer.
(6) Outdoor Generator Sets. Where an
outdoor housed generator set is
equipped with a readily accessible
disconnecting means located within
sight of the building or structure
supplied, an additional disconnecting
means shall not be required where
ungrounded conductors serve or pass
through the building or structure.
(6) Outdoor Generator Sets. Where an
outdoor housed generator set is
equipped with a readily accessible
disconnecting means located within
sight of the building or structure
supplied, an additional disconnecting
means shall not be required where
ungrounded conductors serve or pass
through the building or structure. The
disconnecting means shall meet the
requirements of 225.36.
V. Control — Emergency Lighting
Circuits
Added requirements for dimmer
systems listed for emergency use.
V. Control — Emergency Lighting
Circuits
700.23 Dimmer Systems. A dimmer
system containing more than one
dimmer and listed for use in
emergency systems shall be permitted
to be used as a control device for
energizing emergency lighting circuits.
Upon failure of normal power, the
Page 306 of 361
Clarified that the disconnecting means
must comply with 225.36.
As Safe or Safer.
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700.27 Coordination. Emergency
system(s) overcurrent devices shall be
selectively coordinated with all supply
side overcurrent protective devices.
dimmer system shall be permitted to
selectively energize only those branch
circuits required to provide minimum
emergency illumination. All branch
circuits supplied by the dimmer system
cabinet shall comply with the wiring
methods of Article 700.
700.27 Coordination. Emergency
system(s) overcurrent devices shall be
selectively coordinated with all supply
side overcurrent protective devices.
Change Description and Impact to
Worker Safety
Added exception with two conditions
where selective coordination is not
required.
As Safe or Safer.
Exception: Selective coordination shall
not be required in (1) or (2):
(1) Between transformer primary and
secondary overcurrent protective
devices, where only one overcurrent
protective device or set of overcurrent
protective devices exists on the
transformer secondary,
(2) Between overcurrent protective
devices of the same size (ampere
rating) in series.
Article 701
Legally Required Standby Systems
701.7 Transfer Equipment.
(C) Automatic Transfer Switches.
Page 307 of 361
Revised to require that automatic
transfer switches rated 600 volts and
below be listed for use with legally
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III. Sources of Power
Automatic transfer switches shall be
electrically operated and mechanically
held. Automatic transfer switches,
rated 600 VAC and below, shall be
listed for legally required standby
system use.
III. Sources of Power
701.11 Legally Required Standby
Systems.
701.11 Legally Required Standby
Systems.
(B) Generator Set.
(B) Generator Set.
(5) Outdoor Generator Sets. Where an
outdoor housed generator set is
equipped with a readily accessible
disconnecting means located within
sight of the building or structure
supplied, an additional disconnecting
means shall not be required where
ungrounded conductors serve or pass
through the building or structure.
(5) Outdoor Generator Sets. Where an
outdoor housed generator set is
equipped with a readily accessible
disconnecting means located within
sight of the building or structure
supplied, an additional disconnecting
means shall not be required where
ungrounded conductors serve or pass
through the building or structure. The
disconnecting means shall meet the
requirements of 225.36.
701.18 Coordination. Legally required
standby system(s) overcurrent devices
shall be selectively coordinated with all
supply side overcurrent protective
devices.
701.18 Coordination. Legally required
standby system(s) overcurrent devices
shall be selectively coordinated with all
supply side overcurrent protective
devices.
Exception: Selective coordination shall
Page 308 of 361
Change Description and Impact to
Worker Safety
required standby systems.
As Safe or Safer.
Clarified that the disconnecting means
must comply with 225.36.
As Safe or Safer.
Added exception with two conditions
where selective coordination is not
required.
As Safe or Safer.
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Change Description and Impact to
Worker Safety
not be required in (1) or (2):
(1) Between transformer primary and
secondary overcurrent protective
devices, where only one overcurrent
protective device or set of overcurrent
protective devices exists on the
transformer secondary,
(2) Between overcurrent protective
devices of the same size (ampere
rating) in series.
Article 702
Optional Standby Systems
702.5 Capacity and Rating. An optional 702.5 Capacity and Rating.
standby system shall have adequate
capacity and rating for the supply of all (A) Available Short-Circuit Current.
equipment intended to be operated at
Optional standby system equipment
one time. Optional standby system
shall be suitable for the maximum
equipment shall be suitable for the
available short-circuit current at its
maximum available fault current at its
terminals.
terminals. The user of the optional
(B) System Capacity. The calculations
standby system shall be permitted to
of load on the standby source shall be
select the load connected to the
made in accordance with Article
system.
220 or by another approved method.
(1) Manual Transfer Equipment.
Where manual transfer equipment is
used, an optional standby system
shall have adequate capacity and
rating for the supply of all equipment
Page 309 of 361
Revised requirement on the standby
source capacity based on whether
manual or automatic transfer is
employed and on how standby loads
are to be calculated.
As Safe or Safer.
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Change Description and Impact to
Worker Safety
intended to be operated at one time.
The user of the optional standby
system shall be permitted to select
the load connected to the system.
(2) Automatic Transfer Equipment.
Where automatic transfer equipment
is used, an optional standby system
shall comply with (2)(a) or (2)(b).
(a) Full Load. The standby source
shall be capable of supplying the
full load that is transferred by the
automatic transfer equipment.
IV. Sources of Power
(b) Load Management. Where a
system is employed that will
automatically manage the
connected load, the standby
source shall have a capacity
sufficient to supply the maximum
load that will be connected by the
load management system.
IV. Sources of Power
702.11 Outdoor Generator Sets.
Where an outdoor housed generator
set is equipped with a readily
accessible disconnecting means
located within sight of the building or
structure supplied, an additional
702.11 Outdoor Generator Sets.
Where an outdoor housed generator
set is equipped with a readily
accessible disconnecting means
located within sight of the building or
structure supplied, an additional
Page 310 of 361
Clarified that the disconnecting means
must comply with 225.36, which
requires that the disconnecting means
be suitable for service equipment.
As Safe or Safer.
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disconnecting means shall not be
required where ungrounded
conductors serve or pass through the
building or structure.
2008 NEC
disconnecting means shall not be
required where ungrounded
conductors serve or pass through the
building or structure. The
disconnecting means shall meet the
requirements of 225.36.
Article 705 and 708
Article 705 Interconnected Electric
Power Production Sources
Article 708 Critical Operations Power
Systems (COPS)
Change Description and Impact to
Worker Safety
Extensively revised/rewritten and
added two new parts covering “UtilityInteractive Inverters” and “Generators.”
As Safe or Safer.
New article to provide requirements for
the installation, operation, control, and
maintenance of the portions of premise
wiring systems intended to supply,
distribute, and control electricity to
designated critical operations areas of
a building or facility that requires an
electrical supply and distribution
system with a high degree of reliability
and resiliency to natural disasters and
other threats.
As Safe or Safer.
Circuits and Equipment Operating at
Less Than 50 Volts
Article 720
Circuits and Equipment Operating at
Less Than 50 Volts
720.2 Other Articles. Installations
operating at less than 50 volts, direct
720.2 Other Articles. Direct current or
alternating-current installations
Page 311 of 361
Clarified by providing the specific parts
or sections of other articles that are not
subject to the requirements of Article
720.
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current or alternating current, as
covered in Articles 411, 517, 550, 551,
552, 650, 669, 690, 725, and 760 shall
not be required to comply with this
article.
operating at less than 50 volts, as
covered in 411.1 through 411.7; Part
VI of Article 517; Part II of Article 551;
Parts II and III and 552.60(B) of Article
552; 650.1 through 650.8; 669.1
through 669.9; Parts I and VIII of
Article 690; Parts I and III of Article
725; or Parts I and III of Article 760
shall not be required to comply with
this article.
720.3 Hazardous (Classified)
Locations. Installations within the
scope of this article and installed in
hazardous (classified) locations shall
also comply with the appropriate
provisions for hazardous (classified)
locations in other applicable articles of
this Code.
Article 725
Class 1, Class 2, and Class 3 RemoteControl, Signaling, and Power-Limited
Circuits
725.24 Mechanical Execution of Work.
Class 1, Class 2, and Class 3 circuits
shall be installed in a neat and
workmanlike manner. Cables and
conductors installed exposed on the
surface of ceilings and sidewalls shall
be supported by the building structure
in such a manner that the cable will not
be damaged by normal building use.
720.3 Hazardous (Classified)
Locations. Installations coming within
the scope of this article and installed in
hazardous (classified) locations shall
also comply with the appropriate
provisions of Articles 500 through 517.
725.8 Mechanical Execution of Work.
Class 1, Class 2, and Class 3 circuits
shall be installed in a neat and
workmanlike manner. Cables and
conductors installed exposed on the
surface of ceilings and sidewalls shall
be supported by the building structure
in such a manner that the cable will not
be damaged by normal building use.
Page 312 of 361
Change Description and Impact to
Worker Safety
As Safe or Safer.
Removed limitation referencing just
Articles 500 – 517 to include any
applicable articles.
As Safe or Safer.
Revised to add cable ties as a
supporting means.
As Safe or Safer.
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Such cables shall be supported by
straps, staples, hangers, or similar
fittings designed and installed so as
not to damage the cable. The
installation shall also conform with
300.4(D).
725.3 Other Articles.
(B) Spread of Fire or Products of
Combustion. Section 300.21. The
accessible portion of abandoned Class
2, Class 3, and PLTC cables shall be
removed.
2008 NEC
Such cables shall be supported by
straps, staples, hangers, cable ties, or
similar fittings designed and installed
so as not to damage the cable. The
installation shall also comply with
300.4(D).
725.25 Abandoned Cables. The
accessible portion of abandoned Class
2, Class 3, and PLTC cables shall be
removed. Where cables are identified
for future use with a tag, the tag shall
be of sufficient durability to withstand
the environment involved.
725.26 Conductors of Different Circuits
in the Same Cable, Cable Tray,
Enclosure, or Raceway.
725.48 Conductors of Different Circuits
in the Same Cable, Cable Tray,
Enclosure, or Raceway.
(B) Class 1 Circuits with Power Supply
Circuits.
(B) Class 1 Circuits with Power-Supply
Circuits.
(4) In Cable Trays. In cable trays,
where the Class 1 circuit conductors
and power-supply conductors not
functionally associated with them are
separated by a solid fixed barrier of a
material compatible with the cable tray,
or where the power-supply or Class 1
circuit conductors are in a metalenclosed cable.
(4) In Cable Trays. Installations in
cable trays shall comply with
725.48(B)(4)(1) or (B)(4)(2).
Change Description and Impact to
Worker Safety
Relocated requirement on removing
accessible portions of abandoned
cables from 725.3, and added
requirement on the durability of tags
used to identify cable(s) intended for
future use.
As Safe or Safer.
Added new provision permitting
separation of Class 1 circuit
conductors from power supply
conductors in cable trays using Types
AC, MC, MI, or TC cables.
As Safe or Safer.
(1) Class 1 circuit conductors and
power-supply conductors not
functionally associated with the
Class 1 circuit conductors shall be
separated by a solid fixed barrier of
a material compatible with the cable
Page 313 of 361
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Change Description and Impact to
Worker Safety
tray.
725.52 Wiring Methods and Materials
on Load Side of the Class 2 or Class 3
Power Source.
(2) Class 1 circuit conductors and
power-supply conductors not
functionally associated with the
Class 1 circuit conductors shall be
permitted to be installed in a cable
tray without barriers where all of the
conductors are installed with
separate multiconductor Type AC,
Type MC, Type MI, or Type TC
cables and all the conductors in the
cables are insulated at 600 volts.
725.130 Wiring Methods and Materials
on Load Side of the Class 2 or Class 3
Power Source.
(B) Class 2 and Class 3 Wiring
Methods.
(B) Class 2 and Class 3 Wiring
Methods.
725.56 Installation of Conductors of
Different Circuits in the Same Cable,
Enclosure, or Raceway.
Exception No. 3: Bare Class 2
conductors shall be permitted as part
of a listed intrusion protection system
where installed in accordance with the
listing instructions for the system.
725.139 Installation of Conductors of
Different Circuits in the Same Cable,
Enclosure, or Raceway.
(E) Class 2 or Class 3 Cables with
Other Circuit Cables. Jacketed cables
(E) Class 2 or Class 3 Cables with
Other Circuit Cables. Jacketed cables
Page 314 of 361
Added exception to permit bare Class
2 conductors as part of a listed
intrusion protection system. The Code
Panel 3 had much discussion around
this issue since it involved energized
bare conductors most prevalent on
window intrusion detection systems. It
was determined to be a safe
installation technique.
As Safe or Safer.
Revised to include cable trays.
As Safe or Safer.
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of Class 2 or Class 3 circuits shall be
permitted in the same enclosure or
raceway with jacketed cables of any of
the following:
725.61 Applications of Listed Class 2,
Class 3, and PLTC Cables.
of Class 2 or Class 3 circuits shall be
permitted in the same enclosure, cable
tray, or raceway with jacketed cables
of any of the following:
725.154 Applications of Listed Class 2,
Class 3, and PLTC Cables.
(B) Riser. Cables installed in risers
shall be as described in any of (B)(1),
(B)(2), or (B)(3):
(B) Riser. Cables installed in risers
shall be as described in any of (B)(1),
(B)(2), or (B)(3):
(1) Cables installed in vertical runs and
penetrating more than one floor, or
cables installed in vertical runs in a
shaft, shall be Type CL2R or CL3R.
Floor penetrations requiring Type
CL2R or CL3R shall contain only
cables suitable for riser or plenum use.
Listed riser signaling raceways shall be
permitted to be installed in vertical riser
runs in a shaft from floor to floor. Only
Type CL2R, CL3R, CL2P, or CL3P
cables shall be permitted to be
installed in these raceways.
725.61 Applications of Listed Class 2,
Class 3, and PLTC Cables.
(1) Cables installed in vertical runs and
penetrating more than one floor, or
cables installed in vertical runs in a
shaft, shall be Type CL2R or CL3R.
Floor penetrations requiring Type
CL2R or CL3R shall contain only
cables suitable for riser or plenum use.
Listed riser signaling raceways and
listed plenum signaling raceways shall
be permitted to be installed in vertical
riser runs in a shaft from floor to floor.
Only Type CL2R, CL3R, CL2P, or
CL3P cables shall be permitted to be
installed in these raceways.
725.154 Applications of Listed Class 2,
Class 3, and PLTC Cables.
(C) Cable Trays. Cables installed in
cable trays outdoors shall be Type
PLTC. Cables installed in cable trays
(C) Cable Trays. Cables installed in
cable trays outdoors shall be Type
PLTC. Cables installed in cable trays
Page 315 of 361
Change Description and Impact to
Worker Safety
Revised to include listed plenum
signaling raceways.
As Safe or Safer.
Revised to specify that listed generalpurpose, listed riser, and listed plenum
signaling raceways are permitted to be
installed in cable trays.
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indoors shall be Types PLTC, CL3P,
CL3R, CL3, CL2P, CL2R, and CL2.
Listed signaling raceways shall be
permitted for use with cable trays.
2008 NEC
725.61 Applications of Listed Class 2,
Class 3, and PLTC Cables.
indoors shall be Types PLTC, CL3P,
CL3R, CL3, CL2P, CL2R, and CL2.
Listed general-purpose signaling
raceways, listed riser signaling
raceways, and listed plenum signaling
raceways shall be permitted for use
with cable trays.
725.154 Applications of Listed Class 2,
Class 3, and PLTC Cables.
(D) Hazardous (Classified) Locations.
Cables installed in hazardous locations
shall be as described in 725.61(D)(1)
through (D)(4).
(D) Hazardous (Classified) Locations.
Cables installed in hazardous locations
shall be as described in 725.154(D)(1)
through (D)(4).
(4) In Industrial Establishments. In
industrial establishments where the
conditions of maintenance and
supervision ensure that only qualified
persons service the installation, and
where the cable is not subject to
physical damage, Type PLTC cable
that complies with the crush and
impact requirements of Type MC cable
and is identified for such use shall be
permitted to be exposed between the
cable tray and utilization equipment or
device. The cable shall be continuously
supported and protected against
physical damage using mechanical
protection such as dedicated struts,
(4) In Industrial Establishments. In
industrial establishments where the
conditions of maintenance and
supervision ensure that only qualified
persons service the installation,
Type PLTC cable shall be permitted in
accordance with either (1) or (2):
(1) Type PLTC cable, with a metallic
sheath or armor in accordance with
725.179(E), shall be permitted to be
installed exposed. The cable shall be
continuously supported and protected
against physical damage using
mechanical protection such as
dedicated struts, angles, or channels.
Page 316 of 361
Change Description and Impact to
Worker Safety
• 725.154(D)(4): Added provisions for
PLTC-ER cable to be installed
exposed in industrial occupancies.
As Safe or Safer.
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angles, or channels. The cable shall be The cable shall be secured at intervals
secured at intervals not exceeding 1.8 not exceeding 1.8 m (6 ft).
m (6 ft).
(2) Type PLTC cable, without a
metallic sheath or armor, that complies
with the crush and impact
requirements of Type MC cable and
identified for such use with the marking
PLTC-ER, shall be permitted to be
installed exposed. The cable shall be
continuously supported and protected
against physical damage using
mechanical protection such as
dedicated struts, angles, or channels.
The cable shall be secured at intervals
not exceeding 1.8 m (6 ft).
IV. Listing Requirements
IV. Listing Requirements
725.82 Listing and Marking of Class 2,
Class 3, and Type PLTC Cables.
725.179 Listing and Marking of Class
2, Class 3, and Type PLTC Cables.
727.4 Uses Permitted.
(E)…………….Type PLTC cable used
in a wet location shall be listed for use
in wet locations or have a moisture
impervious metal sheath.
Article 727
Instrumentation Tray Cable: Type ITC
727.4 Uses Permitted.
(5) Without a metallic sheath or armor
between cable tray and equipment in
(5) Cable, without a metallic sheath or
armor, that complies with the crush
Page 317 of 361
Change Description and Impact to
Worker Safety
• 725.179(E): Revised to require that
Type PLTC cables used in wet
locations be listed for use in wet
locations or have a moistureimpervious metal sheath.
As Safe or Safer.
Revised to permit exposed,
continuously supported installations of
Type ITC-ER without length limitation.
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lengths not to exceed 15 m (50 ft),
where the cable is supported and
protected against physical damage
using mechanical protection, such as
struts, angles, or channels. The cable
shall be supported and secured at
intervals not exceeding 1.8 m (6 ft).
2008 NEC
and impact requirements of Type MC
cable and is identified for such use with
the marking ITC-ER shall be permitted
to be installed exposed. The cable
shall be continuously supported and
protected against physical damage
using mechanical protection such as
dedicated struts, angles, or channels.
The cable shall be secured at intervals
not exceeding 1.8 m (6 ft).
(6) Between cable tray and equipment
in lengths not to exceed 15 m (50 ft),

where the cable complies with the
crush and impact requirements of Type
MC cable and is identified for such
use. The cable shall be supported and
secured at intervals not exceeding
1.8 m (6 ft).
727.5 Uses Not Permitted.
727.5 Uses Not Permitted.
Type ITC cable shall not be installed
with power, lighting, Class 1, or non–
power-limited circuits.
760.3 Other Articles.
…………………Type ITC cable shall
not be installed with power, lighting,
Class 1 circuits that are not power
limited, or non–power-limited circuits.
Article 760
Fire Alarm Systems
760.3 Other Articles.
(G) Installation of Conductors with
Other Systems. Installations shall
comply with 300.8.
Page 318 of 361
Change Description and Impact to
Worker Safety
As Safe or Safer.
Revised to clarify that Type ITC can be
installed with Class 1 power-limited
circuits.
As Safe or Safer.
Added requirement for fire alarm
system conductors to comply with
300.8.
As Safe or Safer.
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760.8 Mechanical Execution of Work.
Fire alarm circuits shall be installed in
a neat workmanlike manner. Cables
and conductors installed exposed on
the surface of ceilings and sidewalls
shall be supported by the building
structure in such a manner that the
cable will not be damaged by normal
building use. Such cables shall be
supported by straps, staples, hangers,
or similar fittings designed and
installed so as not to damage the
cable. The installation shall also
conform with 300.4(D).
760.24 Mechanical Execution of Work.
Fire alarm circuits shall be installed in
a neat workmanlike manner. Cables
and conductors installed exposed on
the surface of ceilings and sidewalls
shall be supported by the building
structure in such a manner that the
cable will not be damaged by normal
building use. Such cables shall be
supported by straps, staples, cable
ties, hangers, or similar fittings
designed and installed so as not to
damage the cable. The installation
shall also comply with 300.4(D).
760.25 Abandoned Cables. The
accessible portion of abandoned fire
alarm cables shall be removed. Where
cables are identified for future use with
a tag, the tag shall be of sufficient
durability to withstand the environment
involved.
760.30 Fire Alarm Circuit Identification.
Fire alarm circuits shall be identified at
terminal and junction locations in a
manner that helps to prevent
unintentional signals on fire alarm
system circuit(s) during testing and
servicing of other systems.
760.41 NPLFA Circuit Power Source
Requirements.
760.10 Fire Alarm Circuit Identification.
Fire alarm circuits shall be identified at
terminal and junction locations in a
manner that will prevent unintentional
interference with the signaling circuit
during testing and servicing.
760.21 NPLFA Circuit Power Source
Requirements.
Page 319 of 361
Change Description and Impact to
Worker Safety
Added cable ties as a supporting
means.
As Safe or Safer.
Relocated requirement on removing
accessible portions of abandoned
cables, and added requirement on the
durability of tags used to identify
cable(s) intended for future use.
As Safe or Safer.
Revised to specify the intended
objective of identifying fire alarm
circuits at terminal and junction
locations.
As Safe or Safer.
Added requirement for NPLFA power
sources to be supplied by an individual
branch circuit.
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The power source of non–powerlimited fire alarm circuits shall comply
with Chapters 1 through 4, and the
output voltage shall not be more than
600 volts, nominal. These circuits shall
not be supplied through ground-fault
circuit interrupters or arc-fault circuit
interrupters.
(A) Power Source. The power source
of non–power-limited fire alarm circuits
shall comply with Chapters 1 through
4, and the output voltage shall be not
more than 600 volts, nominal.
760.41 Power Sources for PLFA
Circuits. The power source for a
power-limited fire alarm circuit shall be
as specified in 760.41(A), (B), or (C).
These circuits shall not be supplied
through ground-fault circuit interrupters
or arc-fault circuit interrupters.
(B) Branch Circuit. An individual
branch circuit shall be required for the
supply of the power source. This
branch circuit shall not be supplied
through ground-fault circuit interrupters
or arc-fault circuit interrupters.
760.121 Power Sources for PLFA
Circuits.
(A) Power Source. The power source
for a power-limited fire alarm circuit
shall be as specified in 760.121(A)(1),
(A)(2), or (A)(3).
(1) A listed PLFA or Class 3
transformer.
(2) A listed PLFA or Class 3 power
supply.
(3) Listed equipment marked to
identify the PLFA power source.
(B) Branch Circuit. An individual
branch circuit shall be required for the
supply of the power source. This
branch circuit shall not be supplied
through ground-fault circuit interrupters
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Change Description and Impact to
Worker Safety
As Safe or Safer.
Added requirement for PLFA power
sources to be supplied by an individual
branch circuit.
As Safe or Safer.
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760.52 Wiring Methods and Materials
on Load Side of the PLFA Power
Source.
(B) PLFA Wiring Methods and
Materials. Power-limited fire alarm
conductors and cables described in
760.82 shall be installed as detailed in
760.52(B)(1), (B)(2), or (B)(3) of this
section. Devices shall be installed in
accordance with 110.3(B), 300.11(A),
and 300.15.
760.56 Installation of Conductors of
Different PLFA Circuits, Class 2, Class
3, and Communications Circuits in the
Same Cable, Enclosure, or Raceway.
IV. Listing Requirements
760.81 Listing and Marking of NPLFA
Cables. Non–power-limited fire alarm
cables installed as wiring within
buildings shall be listed in accordance
with 760.81(A) and 760.81(B) and as
being resistant to the spread of fire in
accordance with 760.81(C) through
760.81(F), and shall be marked in
accordance with 760.81(G).
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or arc-fault circuit interrupters.
760.130 Wiring Methods and Materials
on Load Side of the PLFA Power
Source.
(B) PLFA Wiring Methods and
Materials. Power-limited fire alarm
conductors and cables described in
760.179 shall be installed as detailed
in 760.130(B)(1), (B)(2), or (B)(3) of
this section and 300.7. Devices shall
be installed in accordance with
110.3(B), 300.11(A), and 300.15.
760.139 Installation of Conductors of
Different PLFA Circuits, Class 2, Class
3, and Communications Circuits in the
Same Cable, Enclosure, Cable Tray, or
Raceway.
IV. Listing Requirements
Change Description and Impact to
Worker Safety
Added 300.7 to compliance
requirements for installation of PLFA
cables and conductors.
As Safe or Safer.
Revised to include cable trays in (A),
(B), (C) and (D).
As Safe or Safer.
Added requirement that NPLFA cables
used in wet locations be listed for use
in wet locations or have a moistureimpervious metal sheath.
760.176 Listing and Marking of NPLFA
Cables. Non–power-limited fire alarm
cables installed as wiring within
buildings shall be listed in accordance
As Safe or Safer.
with 760.176(A) and (B) and as being
resistant to the spread of fire in
accordance with 760.176(C) through
(F), and shall be marked in accordance
with 760.176(G). Cable used in a wet
location shall be listed for use in wet
locations or have a moisture-
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760.82 Listing and Marking of PLFA
Cables and Insulated Continuous LineType Fire Detectors. Type FPL cables
installed as wiring within buildings shall
be listed as being resistant to the
spread of fire and other criteria in
accordance with 760.82(A) through
760.82(H) and shall be marked in
accordance with 760.82(I). Insulated
continuous line-type fire detectors shall
be listed in accordance with 760.82(J).
770.2 Definitions.
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impervious metal sheath.
760.179 Listing and Marking of PLFA
Cables and Insulated Continuous LineType Fire Detectors. Type FPL cables
installed as wiring within buildings shall
be listed as being resistant to the
spread of fire and other criteria in
accordance with 760.179(A) through
(H) and shall be marked in accordance
with 760.179(I). Insulated continuous
line-type fire detectors shall be listed in
accordance with 760.179(J). Cable
used in a wet location shall be listed for
use in wet locations or have a
moisture-impervious metal sheath.
Article 770
Optical Fiber Cables and Raceways
770.2 Definitions. See Article 100. For
purposes of this article, the following
additional definitions apply.
Change Description and Impact to
Worker Safety
Added requirement for PLFA cables
used in wet locations be listed for use
in wet locations or have a moistureimpervious metal sheath.
As Safe or Safer.
Added a reference to Article 100.
As Safe or Safer.
770.2 Definitions.
770.2 Definitions.
770.2 Definitions.
Exposed (to Accidental Contact). A
conductive optical fiber cable in such a As Safe or Safer.
position that, in case of failure of
supports or insulation, contact between
the cable’s non–current-carrying
conductive members and an electrical
circuit may result.
770.2 Definitions.
Added to define a term used
Page 322 of 361
Clarified the meaning of the term as
applied in Article 770.
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770.3 Other Articles. Circuits and
equipment shall comply with 770.3(A)
and 770.3(B). Only those sections of
Article 300 referenced in this article
shall apply to optical fiber cables and
raceways.
(A) Spread of Fire or Products of
Combustion. The requirements of
300.21 for electrical installations shall
also apply to installations of optical
fiber cables and raceways. The
accessible portion of abandoned
optical fiber cables shall be removed.
770.24 Mechanical Execution of Work.
Optical fiber cables shall be installed in
a neat and workmanlike manner.
Cables installed exposed on the
surface of ceilings and sidewalls shall
be supported by the building structure
in such a manner that the cable will not
be damaged by normal building use.
Such cables shall be secured by
straps, staples, hangers, or similar
fittings designed and installed so as
not to damage the cable. The
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Optical Fiber Cable. A factory
assembly of one or more optical fibers
having an overall covering.
770.3 Other Articles. Circuits and
equipment shall comply with 770.3(A)
and (B). Only those sections of
Chapter 2 and Article 300 referenced
in this article shall apply to optical fiber
cables and raceways.
(A) Composite Cables. Composite
optical fiber cables shall be classified
as electrical cables in accordance with
the type of electrical conductors. They
shall be constructed, listed, and
marked in accordance with the
appropriate article for each type of
electrical cable.
770.24 Mechanical Execution of Work.
Optical fiber cables shall be installed in
a neat and workmanlike manner.
Cables installed exposed on the
surface of ceilings and sidewalls shall
be supported by the building structure
in such a manner that the cable will not
be damaged by normal building use.
Such cables shall be secured by
hardware including straps, staples,
cable ties, hangers, or similar fittings
designed and installed so as not to
Page 323 of 361
Change Description and Impact to
Worker Safety
throughout Article 770.
As Safe or Safer.
Specified that Chapter 2 requirements
apply only if referenced. Added new
(A) after relocating abandoned cable
text to 770.25.
As Safe or Safer.
Added cable ties as a securing means.
As Safe or Safer.
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installation shall also conform with
300.4(D) and 300.11.
770.3 Other Articles.
(A) Spread of Fire or Products of
Combustion. The requirements of
300.21 for electrical installations shall
also apply to installations of optical
fiber cables and raceways. The
accessible portion of abandoned
optical fiber cables shall be removed.
770.3 Other Articles.
(A) Spread of Fire or Products of
Combustion. The requirements of
300.21 for electrical installations shall
also apply to installations of optical
fiber cables and raceways. The
accessible portion of abandoned
optical fiber cables shall be removed.
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damage the cable. The installation
shall also conform with 300.4(D) and
300.11.
770.25 Abandoned Cables. The
accessible portion of abandoned
optical fiber cables shall be removed.
Where cables are identified for future
use with a tag, the tag shall be of
sufficient durability to withstand the
environment involved.
770.26 Spread of Fire or Products of
Combustion. Installations of optical
fiber cables and raceways in hollow
spaces, vertical shafts, and ventilation
or air-handling ducts shall be made so
that the possible spread of fire or
products of combustion will not be
substantially increased. Openings
around penetrations of optical fiber
cables and raceways through fireresistant–rated walls, partitions, floors,
or ceilings shall be fire-stopped using
approved methods to maintain the fire
resistance rating.
II. Cables Outside and Entering
Buildings.
770.48 Unlisted Cables and Raceways
Entering Buildings.
Page 324 of 361
Change Description and Impact to
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Relocated requirement on removing
accessible portions of abandoned
cables, and added requirement on the
durability of tags used to identify
cable(s) intended for future use.
As Safe or Safer.
Relocated requirement on the spread
of fire or products of combustion with
new text that is parallel with the
provisions of 300.21.
As Safe or Safer.
Added section to provide specific
installation requirements for unlisted
conductive and nonconductive optical
fiber cable.
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(A) Conductive and Nonconductive
Cables. Unlisted conductive and
nonconductive outside plant optical
fiber cables shall be permitted to be
installed in locations as described in
770.154(C), where the length of the
cable within the building, measured
from its point of entrance, does not
exceed 15 m (50 ft) and the cable
enters the building from the outside
and is terminated in an enclosure.
770.48 Unlisted Cables and Raceways
Entering Buildings.
II. Protection
(B) Nonconductive Cables. Unlisted
nonconductive optical fiber outside
plant optical fiber cables shall be
permitted to enter the building from the
outside and run in raceway systems
installed in compliance with any of the
following articles in Chapter 3: Article
342, Intermediate Metal Conduit: Type
IMC; Article 344, Rigid Metal Conduit:
Type RMC; Article 352, Rigid Polyvinyl
Chloride Conduit: Type PVC; and
Article 358, Electrical Metallic Tubing:
Type EMT.
III. Protection
770.93 Grounding of Entrance Cables.
770.93 Grounding or Interruption of
Page 325 of 361
Change Description and Impact to
Worker Safety
As Safe or Safer.
Added section to provide specific
installation requirements for unlisted
conductive and nonconductive optical
fiber cable.
As Safe or Safer.
Relocated and expanded the detailed
requirements for fiber optic cables
entering buildings.
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Where exposed to contact with electric
light or power conductors, the non–
current-carrying metallic members of
optical fiber cables entering buildings
shall be grounded as close to the point
of entrance as practicable or shall be
interrupted as close to the point of
entrance as practicable by an
insulating joint or equivalent device.
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Non–Current-Carrying Metallic
Members of Optical Fiber Cables.
Optical fiber cables entering the
building or terminating on the outside
of the building shall comply with
770.93(A) or (B).
(A) Entering Buildings. In installations
where an optical fiber cable is exposed
to contact with electric light or power
conductors and the cable enters the
building, the non-current-carrying
metallic members shall be either
grounded as specified in 770.100, or
interrupted by an insulating joint or
equivalent device. The grounding or
interruption shall be as close as
practicable to the point of entrance.
(B) Terminating On the Outside of
Buildings. In installations where an
optical fiber cable is exposed to
contact with electric light or power
conductors and the cable is terminated
on the outside of the building, the non–
current-carrying metallic members
shall be either grounded as specified in
770.100, or interrupted by an insulating
joint or equivalent device. The
grounding or interruption shall be as
close as practicable to the point of
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Change Description and Impact to
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As Safe or Safer.
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termination of the cable.
IV. Grounding Methods
770.100 Entrance Cable Grounding.
Where grounded, the non–currentcarrying metallic members of optical
fiber cables entering buildings shall be
grounded as specified in 770.100(A)
through (D).
(A) Grounding Conductor.
(1) Insulation. The grounding
conductor shall be insulated and shall
be listed.
(2) Material. The grounding conductor
shall be copper or other corrosionresistant conductive material, stranded
or solid.
(3) Size. The grounding conductor
shall not be smaller than 14 AWG. It
shall have a current-carrying capacity
approximately equal to or greater than
that of the metallic member(s). The
grounding conductor shall not be
required to exceed 6 AWG.
(4) Run in Straight Line. The grounding
conductor shall be run to the grounding
electrode in as straight a line as
practicable.
(5) Physical Damage. Where
necessary, the grounding conductor
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Change Description and Impact to
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Inserted specific Part for grounding
and consolidated the requirements
from other sections.
As Safe or Safer.
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shall be guarded from physical
damage. Where the grounding
conductor is run in a metal raceway,
both ends of the raceway shall be
bonded to the grounding conductor or
the same terminal or electrode to
which the grounding conductor is
connected.
(B) Electrode. The grounding
conductor shall be connected in
accordance with 770.100(B)(1), (B)(2),
or (B)(3).
(1) In Buildings or Structures with an
Intersystem Bonding Termination. If
the building or structure served has an
intersystem bonding termination, the
grounding conductor shall be
connected to the intersystem bonding
termination.
(2) In Buildings or Structures with
Grounding Means. If the building or
structure served has no intersystem
bonding termination, the grounding
conductor shall be connected to the
nearest accessible location on the
following:
(1) The building or structure
grounding electrode system as
covered in 250.50
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(2) The grounded interior metal
water piping system, within 1.5 m (5
ft) from its point of entrance to the
building, as covered in 250.52
(3) The power service accessible
means external to enclosures as
covered in 250.94
(4) The metallic power service
raceway
(5) The service equipment
enclosure
(6) The grounding electrode
conductor or the grounding
electrode conductor metal enclosure
(7) The grounding conductor or the
grounding electrode of a building or
structure disconnecting means that
is grounded to an electrode as
covered in 250.32
(3) In Buildings or Structures Without
Intersystem Bonding Termination or
Grounding Means. If the building or
structure served has no intersystem
bonding termination or grounding
means, as described in 770.100(B)(2),
the grounding conductor shall be
connected to either of the following:
(1) To any one of the individual
electrodes described in
250.52(A)(1), (A)(2), (A)(3), or
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Change Description and Impact to
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(A)(4).
(2) If the building or structure served
has no grounding means, as
described in 770.100(B)(2) or
(B)(3)(1), to an effectively grounded
metal structure or to a ground rod or
pipe not less than 1.5 m (5 ft) in
length and 12.7 mm ( in.) in
diameter, driven, where practicable,
into permanently damp earth and
separated from lightning conductors
as covered in 800.53 and at least
1.8 m (6 ft) from electrodes of other
systems. Steam or hot water pipes
or air terminal conductors (lightningrod conductors) shall not be
employed as electrodes for
protectors.
(C) Electrode Connection.
Connections to grounding electrodes
shall comply with 250.70.
(D) Bonding of Electrodes. A bonding
jumper not smaller than 6 AWG copper
or equivalent shall be connected
between the grounding electrode and
power grounding electrode system at
the building or structure served where
separate electrodes are used.
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Change Description and Impact to
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Exception: At mobile homes as
covered in 770.106.
V. Installation Methods Within
Buildings
770.113 Installation and Marking of
Listed Optical Fiber Cables. Listed
optical fiber cables shall be installed as
wiring within buildings. Optical fiber
770.110 Raceways for Optical Fiber
Cables. Where optical fiber cables are
installed in a raceway, the raceway
shall be either of a type permitted in
Chapter 3 and installed in accordance
with Chapter 3 or listed plenum optical
fiber raceway, listed riser optical fiber
raceway, or listed general-purpose
optical fiber raceway selected in
accordance with the provisions of
770.154, and installed in accordance
with 362.24 through 362.56, where the
requirements applicable to electrical
nonmetallic tubing apply. Where optical
fiber cables are installed in raceway
without current-carrying conductors,
the raceway fill tables of Chapter 3 and
Chapter 9 shall not apply. Where
nonconductive optical fiber cables are
installed with electric conductors in a
raceway, the raceway fill tables of
Chapter 3 and Chapter 9 shall apply.
770.113 Installation of Optical Fiber
Cables. Optical fiber cables installed in
buildings shall be listed.
Page 331 of 361
Change Description and Impact to
Worker Safety
Clarified that raceway fill provisions
apply to Chapter 3 raceways and to
listed plenum, riser, and generalpurpose optical fiber raceways.
As Safe or Safer.
Relocated information and revised
entire part to consolidate and clarify
requirements.
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cables shall be marked in accordance
with Table 770.113.
2008 NEC
770.133 Installation of Optical Fibers
and Electrical Conductors.
Exception: Optical fiber cables that
comply with 770.48 shall not be
required to be listed.

770.133 Installation of Optical Fibers
and Electrical Conductors.
(A) With Conductors for Electric Light,
Power, Class 1, Non–Power-Limited
Fire Alarm, or Medium Power NetworkPowered Broadband Communications
Circuits.
(A) With Conductors for Electric Light,
Power, Class 1, Non–Power-Limited
Fire Alarm, or Medium Power NetworkPowered Broadband Communications
Circuits.
770.133 Installation of Optical Fibers
and Electrical Conductors.
(C) Grounding. Non–current-carrying
conductive members of optical fiber
cables shall be grounded in
accordance with Article 250.
Change Description and Impact to
Worker Safety
As Safe or Safer.
Added exception to permit optical fiber
cables in the same raceway, outlet
box, or other enclosure where
separated by a permanent barrier or a
listed divider.
As Safe or Safer.
Exception No. 5: Where all of the
conductors of electric light, power,
Class 1, non-power-limited fire alarm,
and medium-power network-powered
broadband communications circuits are
separated from all of the optical fiber
cables by a permanent barrier or listed
divider.
770.133 Installation of Optical Fibers
Added requirement prohibiting optical
and Electrical Conductors.
fiber cables from being supported by
attachment to the exterior of raceways
(C) Support of Cables. Raceways shall other than raceway-type masts.
be used for their intended purpose.
Optical fiber cables shall not be
As Safe or Safer.
strapped, taped, or attached by any
means to the exterior of any conduit or
raceway as a means of support.
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Exception: Overhead (aerial) spans of
optical fiber cables shall be permitted
to be attached to the exterior of a
raceway-type mast intended for the
attachment and support of such
cables.
770.154 Applications of Listed Optical
Fiber Cables and Raceways.
(B) Riser. Cables installed in risers
shall be as described in any of (B)(1),
(B)(2), or (B)(3).
(1) Cables in Vertical Runs. Cables
installed in vertical runs and
penetrating more than one floor, or
cables installed in vertical runs in a
shaft, shall be Type OFNR or OFCR.
Floor penetrations requiring Type
OFNR or OFCR shall contain only
cables suitable for riser or plenum use.
Listed riser optical fiber raceways and
listed plenum optical fiber raceways
shall also be permitted to be installed
in vertical riser runs in a shaft from
floor to floor. Only Type OFNP, OFCP,
OFNR, and OFCR cables shall be
permitted to be installed in these
raceways.
Article 800
Communications Circuits
Page 333 of 361
Change Description and Impact to
Worker Safety
Added listed plenum optical fiber
raceways as acceptable for use in a
riser.
As Safe or Safer.
Revised to ensure applicability to
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Change Description and Impact to
Worker Safety
modern telecommunications systems
used in new and existing buildings and
structures.
As Safe or Safer.
Added definition to describe the type of
circuit covered by the requirements of
Article 800.
800.2 Definitions.
800.2 Definitions.
Communications Equipment. The
electronic equipment that performs the
telecommunications operations for the
transmission of audio, video, and data,
and including power equipment (e.g.,
dc converters, inverters and batteries)
and technical support equipment (e.g.,
computers).
Communications Circuit. The circuit
that extends voice, audio, video, data,
interactive services, telegraph (except
As Safe or Safer.
radio), outside wiring for fire alarm and
burglar alarm from the communications
utility to the customer’s
communications equipment up to and
including terminal equipment such as a
telephone, fax machine, or answering
machine.
800.2 Definitions.
Clarified meaning of the term as used
in Article 800 requirements.
Exposed (to Accidental Contact). A
circuit that is in such a position that, in As Safe or Safer.
case of failure of supports or insulation,
contact with another circuit may result.
800.3 Other Articles.
Added requirement for networkpowered broadband communications
(C) Network-Powered Broadband
systems to comply with Article 830.
Communications Systems. Article 830
shall apply to network-powered
As Safe or Safer.
broadband communications systems.
800.2 Definitions.
Exposed. A circuit that is in such a
position that, in case of failure of
supports and insulation, contact with
another circuit may result.
800.3 Other Articles.
(C) Spread of Fire or Products of
Combustion. Section 300.21 shall
apply. The accessible portion of
abandoned communications cables
shall not be permitted to remain.
800.24 Mechanical Execution of Work.
800.24 Mechanical Execution of Work.
Page 334 of 361
Added cable ties as a securing means.
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Communications circuits and
equipment shall be installed in a neat
and workmanlike manner. Cables
installed exposed on the surface of
ceilings and sidewalls shall be
supported by the building structure in
such a manner that the cable will not
be damaged by normal building use.
Such cables shall be secured by
straps, staples, hangers, or similar
fittings designed and installed so as
not to damage the cable. The
installation shall also conform with
300.4(D) and 300.11.
800.3 Other Articles.
(C) Spread of Fire or Products of
Combustion. Section 300.21 shall
apply. The accessible portion of
abandoned communications cables
shall not be permitted to remain.
800.3 Other Articles.
(C) Spread of Fire or Products of
Combustion. Section 300.21 shall
apply. The accessible portion of
abandoned communications cables
shall not be permitted to remain.
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Communications circuits and
equipment shall be installed in a neat
and workmanlike manner. Cables
installed exposed on the surface of
ceilings and sidewalls shall be
supported by the building structure in
such a manner that the cable will not
be damaged by normal building use.
Such cables shall be secured by
hardware, including straps, staples,
cable ties, hangers, or similar fittings
designed and installed so as not to
damage the cable. The installation
shall also conform to 300.4(D) and
300.11.
800.25 Abandoned Cables. The
accessible portion of abandoned
communications cables shall be
removed. Where cables are identified
for future use with a tag, the tag shall
be of sufficient durability to withstand
the environment involved.
800.26 Spread of Fire or Products of
Combustion. Installations of
communications cables and
communications raceways in hollow
spaces, vertical shafts, and ventilation
or air-handling ducts shall be made so
that the possible spread of fire or
products of combustion will not be
substantially increased. Openings
Page 335 of 361
Change Description and Impact to
Worker Safety
As Safe or Safer.
Relocated requirement on removing
accessible portions of abandoned
cables, and added requirement on the
durability of tags used to identify
cable(s) intended for future use.
As Safe or Safer.
Relocated requirement on the spread
of fire or products of combustion with
new text that is parallel with the
provisions of 300.21.
As Safe or Safer.
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Change Description and Impact to
Worker Safety
III. Protection
around penetrations of
communications cables and
communications raceways through fireresistant-rated walls, partitions, floors,
or ceilings shall be fire-stopped using
approved methods to maintain the fire
resistance rating.
800.48 Unlisted Cables Entering
Buildings. Unlisted outside plant
communications cables shall be
permitted to be installed in locations as
described in 800.154(C) where the
length of the cable within the building,
measured from its point of entrance,
does not exceed 15 m (50 ft) and the
cable enters the building from the
outside and is terminated in an
enclosure or on a listed primary
protector.
III. Protection
800.90 Protective Devices.
800.90 Protective Devices.
(A) Application.
(A) Application.
Clarified that for the purposes of this
section, exposure is subject to
accidental contact with electric light or
power conductors operating at over
300 volts to ground.
(1) Fuseless Primary Protectors.
(1) Fuseless Primary Protectors.
As Safe or Safer.
(b) Where insulated conductors in
accordance with 800.50(A) are used to
extend circuits to a building from a
cable with an effectively grounded
(b) Where insulated conductors in
accordance with 800.50(A) are used to
extend circuits to a building from a
cable with an effectively grounded
Page 336 of 361
Provided requirements for unlisted
outside plant communications cables
entering buildings.
As Safe or Safer.
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metallic sheath member(s) and where
the conductors in the cable or cable
stub, or the connections between the
insulated conductors and the exposed
plant, safely fuse on all currents
greater than the current-carrying
capacity of the primary protector, or
the associated insulated conductors
and of the primary protector grounding
conductor
metallic sheath member(s) and where
the conductors in the cable or cable
stub, or the connections between the
insulated conductors and the plant
exposed to accidental contact with
electric light or power conductors
operating at greater than 300 volts to
ground, safely fuse on all currents
greater than the current-carrying
capacity of the primary protector, or the
associated insulated conductors and of
the primary protector grounding
conductor
(c) Where insulated conductors in
accordance with 800.50(A) or
800.50(B) are used to extend circuits
to a building from other than a cable
with metallic sheath member(s), where
(1) the primary protector is listed as
being suitable for this purpose for
application with circuits extending from
other than a cable with metallic sheath
members, and (2) the connections of
the insulated conductors to the
exposed plant or the conductors of the
exposed plant safely fuse on all
currents greater than the currentcarrying capacity of the primary
protector, or associated insulated
conductors and of the primary
(c) Where insulated conductors in
accordance with 800.50(A) or (B) are
used to extend circuits to a building
from other than a cable with metallic
sheath member(s), where (1) the
primary protector is listed as being
suitable for this purpose for application
with circuits extending from other than
a cable with metallic sheath members,
and (2) the connections of the
insulated conductors to the plant
exposed to accidental contact with
electric light or power conductors
operating at greater than 300 volts to
ground or the conductors of the plant
exposed to accidental contact with
electric light or power conductors
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protector grounding conductor.
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Change Description and Impact to
Worker Safety
operating at greater than 300 volts to
ground safely fuse on all currents
greater than the current-carrying
capacity of the primary protector,
or associated insulated conductors and
of the primary protector grounding
conductor
(d) Where insulated conductors in
accordance with 800.50(A) are used to
extend circuits aerially to a building
from an unexposed buried or
underground circuit
(d) Where insulated conductors in
accordance with 800.50(A) are used to
extend circuits aerially to a building
from a buried or underground circuit
that is unexposed to accidental contact
with electric light or power conductors
operating at greater than 300 volts to
ground
800.93 Cable Grounding. The metallic 800.93 Grounding or Interruption of
sheath of communications cables
Metallic Sheath Members of
entering buildings shall be grounded as Communications Cables.
close as practicable to the point of
Communications cables entering the
entrance or shall be interrupted as
building or terminating on the outside
close to the point of entrance as
of the building shall comply with
practicable by an insulating joint or
800.93(A) or (B).
equivalent device.
(A) Entering Buildings. In installations
where the communications cable
enters a building, the metallic sheath
members of the cable shall be either
grounded as specified in 800.100 or
interrupted by an insulating joint or
equivalent device. The grounding or
Page 338 of 361
Clarified location of cable grounding
connections for cable terminations
inside and outside of buildings.
As Safe or Safer.
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interruption shall be as close as
practicable to the point of entrance.
IV. Grounding Methods
(B) Terminating on the Outside of
Buildings. In installations where the
communications cable is terminated on
the outside of the building, the metallic
sheath members of the cable shall be
either grounded as specified in
800.100 or interrupted by an insulating
joint or equivalent device. The
grounding or interruption shall be as
close as practicable to the point of
termination of the cable.
IV. Grounding Methods
800.100 Cable and Primary Protector
Grounding.
800.100 Cable and Primary Protector
Grounding.
(B) Electrode. The grounding
conductor shall be connected in
accordance with 800.100(B)(1) and
(B)(2).
(B) Electrode. The grounding
conductor shall be connected in
accordance with 800.100(B)(1), (B)(2),
or (B)(3).
(1) In Buildings or Structures with
Grounding Means. To the nearest
accessible location on the following:
(1) The building or structure grounding
electrode system as covered in 250.50
(2) The grounded interior metal water
piping system, within 1.5 m (5 ft) from
(1) In Buildings or Structures with an
Intersystem Bonding Termination. If
the building or structure served has an
intersystem bonding termination, the
grounding conductor shall be
connected to the intersystem bonding
termination.
Page 339 of 361
Provided requirements for connecting
the grounding conductor at buildings
with an intersystem bonding
termination, at buildings with only a
grounding means, and at buildings
without either item.
As Safe or Safer.
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its point of entrance to the building, as
covered in 250.52
(3) The power service accessible
means external to enclosures as
covered in 250.94
(4) The metallic power service raceway
(5) The service equipment enclosure
(6) The grounding electrode conductor
or the grounding electrode conductor
metal enclosure
(7) The grounding conductor or the
grounding electrode of a building or
structure disconnecting means that is
grounded to an electrode as covered in
250.32
For purposes of this section, the
mobile home service equipment or the
mobile home disconnecting means, as
described in 800.90(B), shall be
considered accessible.
(2) In Buildings or Structures Without
Grounding Means. If the building or
structure served has no grounding
means, as described in 800.100(B)(1),
the grounding conductor shall be
connected to either of the following:
(1) To any one of the individual
electrodes described in
250.52(A)(1), (A)(2), (A)(3), or
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(2) In Buildings or Structures with
Grounding Means. If the building or
structure served has no intersystem
bonding termination, the grounding
conductor shall be connected to the
nearest accessible location on the
following:
(1) The building or structure
grounding electrode system as
covered in 250.50
(2) The grounded interior metal
water piping system, within 1.5 m (5
ft) from its point of entrance to the
building, as covered in 250.52
(3) The power service accessible
means external to enclosures as
covered in 250.94
(4) The metallic power service
raceway
(5) The service equipment
enclosure
(6) The grounding electrode
conductor or the grounding
electrode conductor metal enclosure
(7) The grounding conductor or the
grounding electrode of a building or
structure disconnecting means that
is grounded to an electrode as
covered in 250.32
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(A)(4)
(2) If the building or structure
served has no grounding means, as
described in 800.100(B)(1) or
(B)(2)(1), to an effectively grounded
metal structure or to a ground rod
or pipe not less than 1.5 m (5 ft) in
length and 12.7 mm (1⁄2 in.) in
diameter, driven, where practicable,
into permanently damp earth and
separated from lightning conductors
as covered in 800.53 and at least
1.8 m (6 ft) from electrodes of other
systems. Steam or hot water pipes
or air terminal conductors
(lightning-rod conductors) shall not
be employed as electrodes for
protectors.
800.133 Installation of
Communications Wires, Cables, and
Equipment.
A bonding device intended to provide a
termination point for the grounding
conductor (intersystem bonding) shall
not interfere with the opening of an
equipment enclosure. A bonding
device shall be mounted on nonremovable parts. A bonding device
shall not be mounted on a door or
cover even if the door or cover is nonremovable.
For purposes of this section, the
mobile home service equipment or the
mobile home disconnecting means, as
described in 800.90(B), shall be
considered accessible.
800.133 Installation of
Communications Wires, Cables, and
Equipment.
Revised to include installations in
cable trays.
As Safe or Safer.
(A) Separation from Other Conductors.
(1) In Raceways, Boxes, and Cables.
(a) Other Power-Limited Circuits.
Communications cables shall be
permitted in the same raceway or
enclosure with cables of any of the
following:
(A) Separation from Other Conductors.
(1) In Raceways, Cable Trays, Boxes,
and Cables.
(a) Other Power-Limited Circuits.
Communications cables shall be
permitted in the same raceway, cable
tray, or enclosure with cables of any of
the following:
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800.154 Applications of Listed
Communications Wires and Cables
and Communications Raceways.
800.154 Applications of Listed
Communications Wires and Cables
and Communications Raceways.
(B) Riser. Cables installed in risers
shall comply with 800.154(B)(1), (B)(2),
or (B)(3).
(1) Cables in Vertical Runs. Cables
installed in vertical runs and
penetrating more than one floor, or
cables installed in vertical runs in a
shaft, shall be Type CMR. Floor
penetrations requiring Type CMR shall
contain only cables suitable for riser or
plenum use. Abandoned cables shall
not be permitted to remain. Listed riser
communications raceways shall be
permitted to be installed in vertical riser
runs in a shaft from floor to floor. Only
Type CMR and CMP cables shall be
permitted to be installed in these
raceways.
800.154 Applications of Listed
Communications Wires and Cables
and Communications Raceways.
(B) Riser. Cables installed in risers
shall comply with 800.154(B)(1), (B)(2),
or (B)(3).
(1) Cables in Vertical Runs. Cables
installed in vertical runs and
penetrating more than one floor, or
cables installed in vertical runs in a
shaft, shall be Type CMR. Floor
penetrations requiring Type CMR shall
contain only cables suitable for riser or
plenum use. Listed riser
communications raceways and listed
plenum communications raceways
shall be permitted to be installed in
vertical riser runs in a shaft from floor
to floor. Only Type CMR and CMP
cables shall be permitted to be
installed in these raceways.
800.154 Applications of Listed
Communications Wires and Cables
and Communications Raceways.
(E) Other Wiring Within Buildings.
Cables installed in building locations
other than the locations covered in
800.154(A) through 800.154(D) shall
be in accordance with 800.154(E)(1)
(C) Other Wiring Within Buildings.
Cables installed in building locations
other than the locations covered in
800.154(A), (B), (D), and (G) shall be
in accordance with 800.154(C)(1)
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Change Description and Impact to
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Added listed plenum communication
raceways as acceptable for use in a
riser.
As Safe or Safer.
Added listed riser communications
raceways and listed plenum
communications raceways as being
acceptable for use in other areas
within buildings in addition to plenums
and risers.
As Safe or Safer.
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through (E)(6).
through (C)(6).
(1) General. Cables shall be Type
CMG or Type CM. Listed
communications general-purpose
raceways shall be permitted. Only
Types CMG, CM, CMR, or CMP cables
shall be permitted to be installed in
general-purpose communications
raceways.
(1) General. Cables shall be Type
CMG or Type CM. Listed
communications general-purpose
raceways, listed riser communications
raceways, and listed plenum
communications raceways shall be
permitted. Only Types CMG, CM,
CMR, or CMP cables shall be
permitted to be installed in these
communications raceways.
800.154 Applications of Listed
Communications Wires and Cables
and Communications Raceways.
800.154 Applications of Listed
Communications Wires and Cables
and Communications Raceways.
Change Description and Impact to
Worker Safety
Revised to permit communications
raceways in cable trays.
As Safe or Safer.
(D) Cable Trays. Types CMP, CMR,
CMG, and CM communications cables
shall be permitted to be installed in
cable trays.
(D) Cable Trays. Types CMP, CMR,
CMG, and CM communications cables
shall be permitted to be installed in
cable trays. Communications
raceways, as described in 800.182,
shall be permitted to be installed in
cable trays.
800.179 Communications Wires and
800.179 Communications Wires and
Cables. Communications wires and
Cables. Communications wires and
cables shall have a voltage rating of
cables shall be listed in accordance
not less than 300 volts and shall be
with 800.179(A) through (I) and
listed in accordance with 800.179(A)
marked in accordance with Table
through 800.179(J). Conductors in
800.179. Conductors in
communications cables, other than in a communications cables, other than in a
coaxial cable, shall be copper.
coaxial cable, shall be copper.
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Revised to include relocated
communications cable marking
requirements and to specify insulation
rating of not less than 300 volts for
individual conductors.
As Safe or Safer.
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Table 800.113 Cable Markings
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Change Description and Impact to
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Communications wires and cables
shall have a voltage rating of not less
than 300 volts. The insulation for the
individual conductors, other than the
outer conductor of a coaxial cable,
shall be rated for 300 volts minimum.
The cable voltage rating shall not be
marked on the cable or on the
undercarpet communications wire.
Communications wires and cables
shall have a temperature rating of not
less than 60°C.
Exception: Voltage markings shall be
permitted where the cable has multiple
listings and voltage marking is required
for one or more of the listings.
Table 800.179 Cable Markings
Article 810
Radio and Television Equipment
810.21 Grounding Conductors —
810.21 Grounding Conductors —
Receiving Stations. Grounding
Receiving Stations. Grounding
conductors shall comply with 810.21(A) conductors shall comply with 810.21(A)
through 810.21(K).
through (K).
(F) Electrode. The grounding
conductor shall be connected as
follows:
(F) Electrode. The grounding
conductor shall be connected as
required in (F)(1) through (F)(3).
Page 344 of 361
Provided requirements for connecting
the grounding conductor at buildings
with an intersystem bonding
termination, at buildings with only a
grounding means, and at buildings
without either item.
As Safe or Safer.
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(1) To the nearest accessible location
on the following:
a. The building or structure
grounding electrode system as
covered in 250.50
b. The grounded interior metal
water piping systems, within 1.52 m
(5 ft) from its point of entrance to
the building, as covered in 250.52
c. The power service accessible
means external to the building, as
covered in 250.94
d. The metallic power service
raceway
e. The service equipment
enclosure, or
f. The grounding electrode
conductor or the grounding
electrode conductor metal
enclosures; or
(2) If the building or structure served
has no grounding means, as described
in 810.21(F)(1), to any one of the
individual electrodes described in
250.52; or
(3) If the building or structure served
has no grounding means, as described
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(1) In Buildings or Structures with an
Intersystem Bonding Termination. If
the building or structure served has an
intersystem bonding termination, the
grounding conductor shall be
connected to the intersystem bonding
termination.
(2) In Buildings or Structures with
Grounding Means. If the building or
structure served has no intersystem
bonding termination, the grounding
conductor shall be connected to the
nearest accessible location on the
following:
(1) The building or structure
grounding electrode system
as covered in 250.50
(2) The grounded interior metal
water piping systems,
within 1.52 m (5 ft) from its point of
entrance to the
building, as covered in 250.52
(3) The power service accessible
means external to the
building, as covered in 250.94
(4) The metallic power service
raceway
(5) The service equipment
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in 810.21(F)(1) or (F)(2), to an
effectively grounded metal structure or
to any of the individual electrodes
described in 250.52
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enclosure, or
(6) The grounding electrode
conductor or the grounding
electrode conductor metal
enclosures
A bonding device intended to provide a
termination point for the grounding
conductor (intersystem bonding) shall
not interfere with the opening of an
equipment enclosure. A bonding
device shall be mounted on nonremovable parts. A bonding device
shall not be mounted on a door or
cover even if the door or cover is nonremovable.
(3) In Buildings or Structures Without
Intersystem Bonding Termination or
Grounding Means. If the building or
structure served has no intersystem
bonding termination or grounding
means, as described in 810.21(F)(1).
(1) To any one of the individual
electrodes described in 250.52; or
(2) If the building or structure served
has no grounding means, as
described in 810.21(F)(1) or (F)(2),
to an effectively grounded metal
structure.
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810.71 General. Transmitters shall
comply with 810.71(A) through (C).
810.71 General. Transmitters shall
comply with 810.71(A) through (C).
(B) Grounding of Controls. All external
metal handles and controls accessible
to the operating personnel shall be
effectively grounded.
(B) Grounding of Controls. All external
metal handles and controls accessible
to the operating personnel shall be
effectively connected to an equipment
grounding conductor if the transmitter
is powered by the premises wiring
system or grounded with a conductor
in accordance with 810.21.
Article 820
Community Antenna Television and
Radio Distribution Systems
Exposed (to Accidental Contact). A
circuit in such a position that, in case of
failure of supports and or insulation,
contact with another circuit may result.
Exposed. An exposed cable is one that
is in such a position that, in case of
failure of supports and insulation,
contact with another circuit could
result.
820.15 Energy Limitations. Coaxial
cable shall be permitted to deliver lowenergy power to equipment that is
directly associated with the radio
frequency distribution system if the
voltage is not over 60 volts and if the
current supply is from a transformer or
other device that has energy-limiting
characteristics.
820.15 Power Limitations. Coaxial
cable shall be permitted to deliver
power to equipment that is directly
associated with the radio frequency
distribution system if the voltage is not
over 60 volts and if the current is
supplied by a transformer or other
device that has power-limiting
characteristics.
Power shall be blocked from premises
devices on the network that are not
intended to be powered via the coaxial
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Change Description and Impact to
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Provided specific means for grounding
external metal handles and controls of
transmitters.
As Safe or Safer.
Clarified meaning of the term as used
in Article 820 requirements.
As Safe or Safer.
Added requirement for blocking power
delivered through coaxial cable to
premises devices not intended for
network supply.
As Safe or Safer.
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820.24 Mechanical Execution of Work.
Community antenna television and
radio distribution systems shall be
installed in a neat and workmanlike
manner. Cables installed exposed on
the surface of ceiling and sidewalls
shall be supported by the building
structure in such a manner that the
cable will not be damaged by normal
building use. Such cables shall be
secured by straps, staples, hangers, or
similar fittings designed and installed
so as not to damage the cable. The
installation shall also conform with
300.4(D) and 300.11.
820.3 Other Articles. Circuits and
equipment shall comply with 820.3(A)
through 820.3(G).
(A) Spread of Fire or Products of
Combustion. Section 300.21 shall
apply. The accessible portion of
abandoned coaxial cables shall be
removed.
820.3 Other Articles. Circuits and
equipment shall comply with 820.3(A)
through 820.3(G).
(A) Spread of Fire or Products of
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cable.
820.24 Mechanical Execution of Work.
Community television and radio
distribution systems shall be installed
in a neat and workmanlike manner.
Coaxial cables installed exposed on
the surface of ceiling and sidewalls
shall be supported by the building
structure in such a manner that the
cables will not be damaged by normal
building use. Such cables shall be
secured by hardware including straps,
staples, cable ties, hangers, or similar
fittings designed and installed so as
not to damage the cable. The
installation shall also conform to
300.4(D) and 300.11.
820.25 Abandoned Cables. The
accessible portion of abandoned
coaxial cables shall be removed.
Where cables are identified for future
use with a tag, the tag shall be of
sufficient durability to withstand the
environment involved.
820.26 Spread of Fire or Products of
Combustion. Installations of coaxial
cables and CATV raceways in hollow
spaces, vertical shafts, and ventilation
or air-handling ducts shall be made so
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Change Description and Impact to
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Added cable ties as a securing means.
As Safe or Safer.
Relocated requirements on removing
accessible portions of abandoned
cables, and added requirement on the
durability of tags used to identify
cable(s) intended for future use.
As Safe or Safer.
Relocated requirement on the spread
of fire or products of combustion with
new text that is parallel with the
provisions of 300.21.
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Combustion. Section 300.21 shall
apply. The accessible portion of
abandoned coaxial cables shall be
removed.
III. Protection
820.93 Grounding of Outer Conductive
Shield of a Coaxial Cable. The outer
conductive shield of the coaxial cable
shall be grounded at the building
premises as close to the point of cable
entrance or attachment as practicable.
For purposes of this section, grounding
located at mobile home service
equipment located in sight from, and
not more than 9.0 m (30 ft) from, the
exterior wall of the mobile home it
2008 NEC
that the possible spread of fire or
products of combustion will not be
substantially increased. Openings
around penetrations of coaxial cables
and CATV raceways through fireresistant-rated walls, partitions, floors,
or ceilings shall be firestopped using
approved methods to maintain the fire
resistance rating.
820.48 Unlisted Cables Entering
Buildings. Unlisted outside plant
coaxial cables shall be permitted to be
installed in locations as described in
820.154(D), where the length of the
cable within the building, measured
from its point of entrance, does not
exceed 15 m (50 ft) and the cable
enters the building from the outside
and is terminated at a grounding block.
III. Protection
820.93 Grounding of the Outer
Conductive Shield of Coaxial Cables.
Coaxial cables entering buildings or
attached to buildings shall comply with
820.93(A) or (B). Where the outer
conductive shield of a coaxial cable is
grounded, no other protective devices
shall be required. For purposes of this
section, grounding located at mobile
home service equipment located within
9.0 m (30 ft) of the exterior wall of the
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Change Description and Impact to
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As Safe or Safer.
Provided requirements for unlisted
outside plant coaxial cables entering
buildings.
As Safe or Safer.
Clarified location of cable shield
grounding for cable terminations inside
and outside of buildings and to specify
the location of primary protectors.
As Safe or Safer.
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serves, or at a mobile home
disconnecting means grounded in
accordance with 250.32 and located in
sight from and not more than 9.0 m (30
ft) from the exterior wall of the mobile
home it serves, shall be considered to
meet the requirements of this section.
mobile home it serves, or at a mobile
home disconnecting means grounded
in accordance with 250.32 and located
within 9.0 m (30 ft) of the exterior wall
of the mobile home it serves, shall be
considered to meet the requirements of
this section.
(A) Shield Grounding. Where the outer
conductive shield of a coaxial cable is
grounded, no other protective devices
shall be required.
(A) Entering Buildings. In installations
where the coaxial cable enters the
building, the outer conductive shield
shall be grounded in accordance with
820.100. The grounding shall be as
close as practicable to the point of
entrance.
(B) Shield Protection Devices.
Grounding of a coaxial drop cable
shield by means of a protective device
that does not interrupt the grounding
system within the premises shall be
permitted.
(B) Terminating Outside of the
Building. In installations where the
coaxial cable is terminated outside of
the building, the outer conductive
shield shall be grounded in accordance
with 820.100. The grounding shall be
as close as practicable to the point of
attachment or termination.
(C) Location. Where installed, a listed
primary protector shall be applied on
each community antenna and radio
distribution (CATV) cable external to
the premises. The listed primary
protector shall be located as close as
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Change Description and Impact to
Worker Safety
practicable to the entrance point of the
cable on either side or integral to the
ground block.
(D) Hazardous (Classified) Locations.
Where a primary protector or
equipment providing the primary
protection function is used, it shall not
be located in any hazardous
(classified) location as defined in 500.5
or in the vicinity of easily ignitible
material.
IV. Grounding Methods
820.100 Cable Grounding.
Exception: As permitted in 501.150,
502.150, and 503.150.
IV. Grounding Methods
820.100 Cable Grounding.
(B) Electrode. The grounding
conductor shall be connected in
accordance with 820.100(B)(1) and
(B)(2).
(B) Electrode. The grounding
conductor shall be connected in
accordance with 820.100(B)(1), (B)(2),
or (B)(3).
Provided requirements for connecting
the grounding conductor at buildings
with an intersystem bonding
termination, at buildings with only a
grounding means, and at buildings
without either item.
As Safe or Safer.
(1) In Buildings or Structures with
Grounding Means. To the nearest
accessible location on the following:
(1) The building or structure
grounding electrode system as
covered in 250.50
(2) The grounded interior metal
(1) In Buildings or Structures with an
Intersystem Bonding Termination. If
the building or structure served has an
intersystem bonding termination, the
grounding conductor shall be
connected to the intersystem bonding
termination.
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water piping system, within 1.52 m
(5 ft) from its point of entrance to
the building, as covered in 250.52
(3) The power service accessible
means external to enclosures as
covered in 250.94
(4) The metallic power service
raceway
(5) The service equipment
enclosure
(6) The grounding electrode
conductor or the grounding
electrode conductor metal
enclosure, or
(7) The grounding conductor or the
grounding electrode of a building or
structure disconnecting means that
is grounded to an electrode as
covered in 250.32
(2) In Buildings or Structures Without
Grounding Means. If the building or
structure served has no grounding
means, as described in 820.100(B)(1):
(1) To any one of the individual
electrodes described in
250.52(A)(1), (A)(2), (A)(3), (A)(4);
or,
(2) If the building or structure
served has no grounding means, as
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(2) In Buildings or Structures with
Grounding Means. If the building or
structure served has no intersystem
bonding termination, the grounding
conductor shall be connected to the
nearest accessible location on the
following:
(1) The building or structure
grounding electrode system as
covered in 250.50
(2) The grounded interior metal
water piping system, within 1.52 m
(5 ft) from its point of entrance to the
building, as covered in 250.52
(3) The power service accessible
means external to enclosures as
covered in 250.94
(4) The metallic power service
raceway
(5) The service equipment
enclosure
(6) The grounding electrode
conductor or the grounding
electrode conductor metal
enclosure, or
(7) The grounding conductor or the
grounding electrode of a building or
structure disconnecting means that
is connected to an electrode as
covered in 250.32
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described in 820.100(B)(1) or
(B)(2)(1), to an effectively grounded
metal structure or to any one of the
individual electrodes described in
250.52(A)(5), (A)(6), and (A)(7).
2008 NEC
A bonding device intended to provide a
termination point for the grounding
conductor (intersystem bonding) shall
not interfere with the opening of an
equipment enclosure. A bonding
device shall be mounted on nonremovable parts. A bonding device
shall not be mounted on a door or
cover even if the door or cover is nonremovable.
For purposes of this section, the
mobile home service equipment or the
mobile home disconnecting means, as
described in 820.93, shall be
considered accessible.
(3) In Buildings or Structures Without
Intersystem Bonding Termination or
Grounding Means. If the building or
structure served has no intersystem
bonding termination or grounding
means, as described in 820.100(B)(2),
the grounding conductor shall be
connected to either of the following:
(1) To any one of the individual
electrodes described in
250.52(A)(1), (A)(2), (A)(3), (A)(4);
or,
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820.100 Cable Grounding.
820.133 Installation of Cables and
Equipment. Beyond the point of
grounding, as defined in 820.93, the
cable installation shall comply with
820.133(A) through 820.133(C).
(A) Separation from Other Conductors.
(1) In Raceways and Boxes.
(1) Other Circuits. Coaxial cables
shall be permitted in the same
raceway or enclosure with jacketed
cables of any of the following:
820.154 Applications of Listed CATV
Cables and CATV Raceways.
2008 NEC
(2) If the building or structure served
has no intersystem bonding
termination or grounding means, as
described in 820.100(B)(2) or
(B)(3)(1), to any one of the
individual electrodes described in
250.52(A)(5), (A)(7), and (A)(8).
820.100 Cable Grounding.
(E) Shield Protection Devices.
Grounding of a coaxial drop cable
shield by means of a protective device
that does not interrupt the grounding
system within the premises shall be
permitted.
820.133 Installation of Coaxial Cables
and Equipment. Beyond the point of
grounding, as defined in 820.93, the
coaxial cable installation shall comply
with 820.133(A) and (B).
(A) Separation from Other Conductors.
(1) In Raceways, Cable Trays, and
Boxes.
(a) Other Circuits. Coaxial cables
shall be permitted in the same
raceway, cable tray, or enclosure
with jacketed cables of any of the
following:
820.154 Applications of Listed CATV
Cables and CATV Raceways.
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Added provision to permit use of a
shield protection device for grounding
shield of a coaxial cable.
As Safe or Safer.
Revised to include installations in
cable trays.
As Safe or Safer.
Added listed riser CATV raceways and
listed plenum CATV raceways as
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(D) Other Wiring Within Buildings.
Cables installed in building locations
other than the locations covered in
820.154(A) and 820.154(B) shall be
with any of the requirements in
820.154(D)(1) through (D)(5).
Abandoned cables in hollow spaces
shall not be permitted to remain.
(1) General. Type CATV shall be
permitted. Listed CATV generalpurpose raceways shall be permitted.
Only Types CATV, CATVX, CATVR, or
CATVP cables shall be permitted to be
installed in general-purpose
communications raceways.
VI. Listing Requirements
820.179 Coaxial Cables. Cables shall
be listed in accordance with
820.179(A) through 820.179(D).
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(C) Other Wiring Within Buildings.
Cables installed in building locations
other than the locations covered in
820.154(A) and (B) shall be in
accordance with any of the
requirements in 820.154(C)(1) through
(C)(5).
(1) General. Type CATV shall be
permitted. Listed CATV generalpurpose raceways, listed riser CATV
raceways, and listed plenum CATV
raceways shall be permitted. Only
Types CATV, CATVX, CATVR, or
CATVP cables shall be permitted to be
installed in these CATV raceways.
VI. Listing Requirements
820.179 Coaxial Cables. Cables shall
be listed in accordance with
820.179(A) through (D) and marked in
accordance with Table 820.179. The
cable voltage rating shall not be
marked on the cable.
Exception: Voltage markings shall be
permitted where the cable has multiple
listings and voltage marking is required
for one or more of the listings.
Article 830
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acceptable for use in other areas
within buildings in addition to plenums
and risers.
As Safe or Safer.
Revised to include relocated marking
requirement for coaxial cables.
As Safe or Safer.
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830.15 Power Limitations. Networkpowered broadband communications
systems shall be classified as having
low or medium power sources as
defined in Table 830.15.
830.24 Mechanical Execution of Work.
Network-powered broadband
communications circuits and
equipment shall be installed in a neat
and workmanlike manner. Cables
installed exposed on the surface of
ceilings and sidewalls shall be
supported by the building structure in
such a manner that the cable will not
be damaged by normal building use.
Such cables shall be secured by
straps, staples, hangers, or similar
fittings designed and installed so as
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Network-Powered Broadband
Communications Systems
830.15 Power Limitations. Networkpowered broadband communications
systems shall be classified as having
low or medium-power sources as
specified in 830.15(1) or (2).
(1) Sources shall be classified as
defined in Table 830.15.
(2) Direct-current power sources
exceeding 150 volts to ground, but
no more than 200 volts to ground,
with the current to ground limited to
10 mA dc, that meet the current and
power limitation for medium-power
sources in Table 830.15 shall be
classified as medium-power
sources.
830.24 Mechanical Execution of Work.
Network-powered broadband
communications circuits and
equipment shall be installed in a neat
and workmanlike manner. Cables
installed exposed on the surface of
ceilings and sidewalls shall be
supported by the building structure in
such a manner that the cable will not
be damaged by normal building use.
Such cables shall be secured by
hardware including straps, staples,
cable ties, hangers, or similar fittings
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Change Description and Impact to
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Provided alternative for equipment that
meets the requirements of the table
but are DC voltages.
As Safe or Safer.
Added cable ties as a securing means.
As Safe or Safer.
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not to damage the cable. The
installation shall also conform with
300.4(D) and 300.11.
830.3 Other Articles. Circuits and
equipment shall comply with 830.3(A)
through 830.3(E).
(A) Spread of Fire or Products of
Combustion. Section 300.21 shall
apply. The accessible portion of
abandoned network-powered
broadband communications cables
shall be removed.
830.3 Other Articles. Circuits and
equipment shall comply with 830.3(A)
through 830.3(E).
(A) Spread of Fire or Products of
Combustion. Section 300.21 shall
apply. The accessible portion of
abandoned network-powered
broadband communications cables
shall be removed.
830.93 Grounding or Interruption of
Metallic Members of Network-Powered
Broadband Communications Cables.
2008 NEC
designed and installed so as not to
damage the cable. The installation
shall also conform to 300.4(D) and
300.11.
830.25 Abandoned Cables. The
accessible portion of abandoned
network-powered broadband cables
shall be removed. Where cables are
identified for future use with a tag, the
tag shall be of sufficient durability to
withstand the environment involved.
830.26 Spread of Fire or Products of
Combustion. Installations of networkpowered broadband cables in hollow
spaces, vertical shafts, and ventilation
or air-handling ducts shall be made so
that the possible spread of fire or
products of combustion will not be
substantially increased. Openings
around penetrations of networkpowered broadband cables through
fire-resistant-rated walls, partitions,
floors, or ceilings shall be firestopped
using approved methods to maintain
the fire resistance rating.
830.93 Grounding or Interruption of
Metallic Members of Network-Powered
Broadband Communications Cables.
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Change Description and Impact to
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Relocated requirement on removing
accessible portions of abandoned
cables, and added requirement on the
durability of tags used to identify
cable(s) intended for future use.
As Safe or Safer.
Relocated requirement on the spread
of fire or products of combustion with
new text that is parallel with the
provisions of 300.21.
As Safe or Safer.
Clarified location of cable shield
grounding for cable terminations inside
and outside of buildings.
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The shields of network-powered
broadband communications cables
used for communications or powering
shall be grounded at the building as
close as practicable to the point of
entrance or attachment of the NIU.
Metallic cable members not used for
communications or powering shall be
grounded or interrupted by an
insulating joint or equivalent device as
close as practicable to the point of
entrance or attachment of the NIU.
For purposes of this section, grounding
or interruption of network-powered
broadband communications cable
metallic members installed at mobile
home service equipment located in
sight from and no more than 9.0 m (30
ft) from the exterior wall of the mobile
home it serves, or at a mobile home
disconnecting means grounded in
accordance with 250.32 and located in
sight from and not more than 9.0 m (30
ft) from the exterior wall of the mobile
home it serves, shall be considered to
meet the requirements of this section.
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Change Description and Impact to
Worker Safety
Network-powered communications
cables entering buildings or attaching
As Safe or Safer.
to buildings shall comply with
830.93(A) or (B). For purposes of this
section, grounding located at mobile
home service equipment located within
9.0 m (30 ft) of the exterior wall of the
mobile home it serves, or at a mobile
home disconnecting means grounded
in accordance with 250.32 and located
within 9.0 m (30 ft) of the exterior wall
of the mobile home it serves, shall be
considered to meet the requirements of
this section.
(A) Entering Buildings. In installations
where the network-powered
communications cable enters the
building, the shield shall be grounded
in accordance with 830.100 and
metallic members of the cable not used
for communications or powering shall
be grounded in accordance with
830.100, or interrupted by an insulating
joint or equivalent device. The
grounding or interruption shall be as
close as practicable to the point of
entrance.
(B) Terminating Outside of the
Building. In installations where the
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IV. Grounding Methods
830.100 Cable, Network Interface Unit,
and Primary Protector Grounding.
(B) Electrode. The grounding
conductor shall be connected as
follows.
(1) In Buildings or Structures with
Grounding Means. To the nearest
accessible location on the following:
(2) In Buildings or Structures Without
Grounding Means. If the building or
structure served has no grounding
means, as described in (B)(1), the
grounding conductor shall be
connected to either of the following:
2008 NEC
Change Description and Impact to
Worker Safety
network-powered communications
cable is terminated outside of the
building, the shield shall be grounded
in accordance with 830.100, and
metallic members of the cable not used
for communications or powering shall
be grounded in accordance with
830.100 or interrupted by an insulating
joint or equivalent device. The
grounding or interruption shall be as
close as practicable to the point of
attachment of the NIU.
IV. Grounding Methods
Provided requirements for connecting
the grounding conductor at buildings
830.100 Cable, Network Interface Unit, with an intersystem bonding
and Primary Protector Grounding.
termination, at buildings with only a
grounding means, and at buildings
(B) Electrode. The grounding
without either item.
conductor shall be connected in
accordance with 830.100(B)(1), (B)(2), As Safe or Safer.
or (B)(3).
(1) In Buildings or Structures with an
Intersystem Bonding Termination. If
the building or structure served has an
intersystem bonding termination, the
grounding conductor shall be
connected to the intersystem bonding
termination.
(2) In Buildings or Structures with
Grounding Means. If the building or
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Change Description and Impact to
Worker Safety
structure served has no intersystem
bonding termination, the grounding
conductor shall be connected to the
nearest accessible location on the
following:
V. Wiring Methods Within Buildings
830.133 Installation of Network-
(3) In Buildings or Structures Without
Intersystem Bonding Termination or
Grounding Means. If the building
or structure served has no intersystem
bonding termination or grounding
means, as described in 830.100(B)(2),
the grounding conductor shall be
connected to either of the following:
V. Installation Methods Within
Buildings
830.110 Raceways for Low- and
Medium-Power Network-Powered
Broadband Communications Cables.
Where low- and medium-power
network-powered broadband
communications cables are installed in
a raceway, the raceway shall be of a
type permitted in Chapter 3 and
installed in accordance with Chapter 3.
Exception: Conduit fill restrictions shall
not apply to low-power networkpowered broadband communications
cables.
830.133 Installation of Network-
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Added to provide reference to Chapter
3 requirements for raceway
installations with exception on conduit
fill for low-power broadband systems.
As Safe or Safer.
Revised to include installations in
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Powered Broadband Communications
Cables and Equipment. Cable and
equipment installations within buildings
shall comply with 830.133(A) through
830.133(D), as applicable.
Powered Broadband Communications
Cables and Equipment. Cable and
equipment installations within buildings
shall comply with 830.133(A) through
(C), as applicable.
(A) Separation of Conductors.
(1) In Raceways and Enclosures.
830.133 Installation of NetworkPowered Broadband Communications
Cables and Equipment.
(A) Separation of Conductors.
(1) In Raceways, Cable Trays, and
Enclosures.
830.154 Applications of Low-Power
Network-Powered Broadband
Communications System Cables.
(C) Cable Substitutions. The
substitutions for network-powered
broadband cables listed in Table
830.133 shall be permitted. All cables
in Table 830.133, other than networkpowered broadband cables, shall be
coaxial cables.
(D) Cable Substitutions. The
substitutions for network-powered
broadband cables listed in Table
830.154 shall be permitted. All cables
in Table 830.154, other than networkpowered broadband cables, shall be
coaxial cables.
Change Description and Impact to
Worker Safety
cable trays.
As Safe or Safer.
Relocated provisions for cable
substitutions.
As Safe or Safer.
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