MECKLENBURG COUNTY
Land Use & Environmental Services Agency
Code Enforcement
10/12/11 ELECTRICAL CONSISTENCY MEETING
Code Consistency Questions
1. On a sub panel installation in a residential garage of 4 two-wire branch circuits I say that
the minimum feeder ampacity should be 60-Amp, based on the fact that the disconnecting
means must be rated at 60-Amp by code. The inspector says that it is based on the
computed load, 45 amps, and could be 45 Amp or 50Amp. Who is correct?
The inspector if attached, 215.2, (A) (1), applies and feeder conductors shall have an
ampacity not less than required to supply the load as calculated per Article 220. Thus the
40/50 ampere feeder could be acceptable. NEC 215.5, allows the AHJ to ask for a feeder
diagram and details. Now let’s review the detached structure option which I believe the
question was designed for; 225.39 (D), indicates that the rating of the disconnect shall not be
less than 60 ampere since there are (4 two-wire branch circuits) mentioned. The 60 ampere
requirement is not correct. Article 225.5 states “The ampacity of outdoor branch-circuit and
feeder conductors shall be in accordance with 310.15 based on loads as determined under
220.10 and Part III of Article 220”, thus the conductor ampacity may be sized according to the
computed load and still have the disconnect rated at 60 Amp.
2. We installed a separately derived system (transformer) at the far end of a large warehouse.
We proposed to use a primary equipment ground on the circuit that would be sized based on
the required grounding electrode conductor size. This would have one conductor serve as
both the equipment grounding and grounding electrode conductor. The inspector said no,
they are separate conductors but cannot point to a code requirement. Is there a prohibition on
this type of installation?
Yes, The grounding electrode conductor is required to be routed from the grounding electrode
to the separately derived system. 250.30(A) (3).
250.30(A)(3) Grounding Electrode Conductor, Single Separately Derived System
A grounding electrode conductor for a single separately derived system shall be sized in
accordance with 250.66 for the derived phase conductors and shall be used to connect the
grounded conductor of the derived system to the grounding electrode as specified in
250.30(A)(7). This connection shall be made at the same point on the separately derived
system where the system bonding jumper is installed.
The question has it routed from the primary overcurrent enclosure and not the grounding
PEOPLE ● PRIDE ● PROGRESS ● PARTNERSHIPS
700 North Tryon Street • Charlotte, North Carolina 28202 • Phone (704) 336-3545• Fax (704) 336-3839
www.meckpermit.com
MECKLENBURG COUNTY
Land Use & Environmental Services Agency
Code Enforcement
Page 2 of 8
electrode. If the grounding electrode conductor was routed from the electrode and installed
with the primary conductors, there is nothing in the code that would prohibit the equipment
grounding conductor and the grounding electrode conductor to occupy the same raceway.
250.30(A) (5) requires the installation of the grounding electrode conductor to comply with
250.64(A) (B) (C) & (E). 250.64(C) requires the conductor to be one continuous length
without a splice. 250.64(E) has requirements for the conductor in enclosures and bonding
applies and each end of a ferrous metal raceways. Though PRESENTLY not prohibited by the
code the installation requirements really makes it unrealistic in most applications to utilized
one conductor for both the grounding electrode conductor and the equipment grounding
conductor.
3. An air-conditioner consisting of two separate units is installed in a residence. The self-
contained fan unit is inside the house and a hermetic refrigerant unit outside. Is it permitted to
use the supplied five-conductor (with ground) cable between the two units? The conditions
and materials are: a 15-amp, two-pole circuit feeds the unit outside and the cable between
the units is a CSA listed# 14 AWG rated 600 volts TC cable. The cable is sunlight resistant
and suitable for a wet location. The cable is tie wrapped to the insulated Freon lines between
the two units and runs through the wall of the house with them. Is this cable a proper one to
use, considering it is rated only as Type TC cable?
NO – code reference 336.12(2)
336.12 Uses Not Permitted
Type TC tray cable shall not be installed or used as follows:
(1) Installed where it will be exposed to physical damage
(2) Installed outside a raceway or cable tray system, except as permitted in 336.10(7)
(3) Used where exposed to direct rays of the sun, unless identified as sunlight resistant
(4) Direct buried, unless identified for such use
Product Standard used is UL 1277, Electrical Power and Control Tray Cables with Optional
Optical-Fiber Members under
Category QPOR on page 208 of the UL white book.
Although the general rule in 336.12(2) only permits type TC cable to be installed inside a
raceway or cable tray, other than as permitted in 336.10(7) in industrial establishments for
Type TC–ER shall be permitted between a cable tray and the utilization equipment or device,
or 336.12(4) for direct burial where identified for such use and 336.10 (4) In outdoor locations
supported by a messenger wire. Therefore the application as presented would not be code
compliant.
PEOPLE ● PRIDE ● PROGRESS ● PARTNERSHIPS
700 North Tryon Street • Charlotte, North Carolina 28202 • Phone (704) 336-3545• Fax (704) 336-3839
www.meckpermit.com
MECKLENBURG COUNTY
Land Use & Environmental Services Agency
Code Enforcement
Page 3 of 8
4. If there is electrical power in a detached residential garage, and an electric garage door
opener has a light with a wall-mounted control for the light in the unit, does this count as the
required lighting outlet in Section 210.70?
Maybe, depending on if the lighting source is on a separate circuit and will illuminate the area
without having to open and close the garage door opener mechanism that normally allows for
the light to be shut off after a timing sequence. Section 210.70 (A) (2) (a), pg 54, requires a
wall switch controlled lighting outlet. (b) Also requires detached garages to have one wall
switched lighting outlet on the exterior side of outdoor entrances and exits. Just to have a
light that cycles on by the function of the garage door opening and closing and then switching
off after a period of time does not meet need for lighting while one is in the area for
unspecified periods of time.
5. We installed two feeders in a raceway. Does each circuit need an equipment grounding
conductor?
Section 250.122 provides the requirements for sizing the equipment grounding conductor in a
raceway based on the branch circuit overcurrent device. Where multiple circuits are installed
in the same raceway 250.122(C) would apply.
250.122(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.
This section does not address multiple feeders in a raceway. It would be my interpretation
that this section would also apply to feeders even though it is not specifically addressed in this
code section.
6. The manufacturers of recessed light fixtures list the type of light bulbs that are approved
to be installed within their fixtures. The newer type of medium base fluorescent light bulb is
not listed for use in these recessed cans. Many people are buying them to conserve energy
and are installing them in the recessed cans. Is this permissible?
Yes, this is permissible providing you install the lamp in accordance with its markings and do
not exceed the wattage rating on the luminaire...
The question is dealing with the proliferation of what the industry calls compact fluorescent
lamps. UL Lists these as Self Ballasted Lamps and Lamp Adapters, (OOLR), located on page
269 in the 2011 White Book. The Guide Information states these products have been
investigated for use in the smaller of a 6- or 8-in. diameter recessed luminaire, if they will
PEOPLE ● PRIDE ● PROGRESS ● PARTNERSHIPS
700 North Tryon Street • Charlotte, North Carolina 28202 • Phone (704) 336-3545• Fax (704) 336-3839
www.meckpermit.com
MECKLENBURG COUNTY
Land Use & Environmental Services Agency
Code Enforcement
Page 4 of 8
physically fit, and are intended for use in totally enclosed, recessed luminaires unless marked
and stated not for such use.
7. Can a single-pole switch control the emergency lighting on the critical branch for a nurse’s
station?
Answer: Yes, if the switch is accessible only to authorized persons.
517.26 Application of Other Articles.
The essential electrical system shall meet the requirements of Article 700, except as amended
by Article 517.
V. Control — Emergency Lighting Circuits
700.20 Switch Requirements.
The switch or switches installed in emergency lighting circuits shall be arranged so that only
authorized persons have control of emergency lighting.
Exception No. 1: Where two or more single-throw switches are connected in parallel to control
a single circuit, at least one of these switches shall be accessible only to authorized persons.
Exception No. 2: Additional switches that act only to put emergency lights into operation but
not disconnect them shall be permissible. Switches connected in series or 3- and 4-way
switches shall not be used.
700.12 requires that the emergency power be on within 10 seconds, and the building codes
and building code officials generally require the emergency lights to be on within this time.
8. Who is qualified to perform a GFP test of a GFP main breaker service?
Requirements for testing these systems can be found in 230.95(C) but the NEC is silent on
any qualifications to perform such testing. The test is required to be performed in accordance
with manufacturer’s instructions and a written record of the test is required. Some AHJs may
have additional requirements such as witnessing the test.
PEOPLE ● PRIDE ● PROGRESS ● PARTNERSHIPS
700 North Tryon Street • Charlotte, North Carolina 28202 • Phone (704) 336-3545• Fax (704) 336-3839
www.meckpermit.com
MECKLENBURG COUNTY
Land Use & Environmental Services Agency
Code Enforcement
Page 5 of 8
9. Where are disconnects required on PV systems?
Locations for disconnects is found in Part III of article 690.
III. Disconnecting Means
690.13 All Conductors.
Means shall be provided to disconnect all current-carrying conductors of a photovoltaic power
source from all other conductors in a building or other structure. A switch, circuit breaker, or
other device, either ac or dc, shall not be installed in a grounded conductor if operation of that
switch, circuit breaker, or other device leaves the marked, grounded conductor in an
ungrounded and energized state.
Exception: A switch or circuit breaker that is part of a ground-fault detection system required
by 690.5 shall be permitted to open the grounded conductor when that switch or circuit
breaker is automatically opened as a normal function of the device in responding to ground
faults. The switch or circuit breaker shall indicate the presence of a ground fault.
FPN: The grounded conductor may have a bolted or terminal disconnecting means to allow
maintenance or troubleshooting by qualified personnel.
690.14 Additional Provisions.
Photovoltaic disconnecting means shall comply with 690.14(A) through (D).
(A) Disconnecting Means. The disconnecting means shall not be required to be suitable as
service equipment and shall comply with 690.17.
(B) Equipment. Equipment such as photovoltaic source circuit isolating switches, overcurrent
devices, and blocking diodes shall be permitted on the photovoltaic side of the photovoltaic
disconnecting means.
(C) Requirements for Disconnecting Means. Means shall be provided to disconnect all
conductors in a building or other structure from the photovoltaic system conductors.
(1) Location. The photovoltaic disconnecting means shall be installed at a readily accessible
location either on the outside of a building or structure or inside nearest the point of entrance
of the system conductors.
Exception: Installations that comply with 690.31(E) shall be permitted to have the
PEOPLE ● PRIDE ● PROGRESS ● PARTNERSHIPS
700 North Tryon Street • Charlotte, North Carolina 28202 • Phone (704) 336-3545• Fax (704) 336-3839
www.meckpermit.com
MECKLENBURG COUNTY
Land Use & Environmental Services Agency
Code Enforcement
Page 6 of 8
disconnecting means located remote from the point of entry of the system conductors. The
photovoltaic system disconnecting means shall not be installed in bathrooms.
(2) Marking. Each photovoltaic system disconnecting means shall be permanently marked to
identify it as a photovoltaic system disconnect.
(3) Suitable for Use. Each photovoltaic system disconnecting means shall be suitable for the
prevailing conditions. Equipment installed in hazardous (classified) locations shall comply with
the requirements of Articles 500 through 517.
(4) Maximum Number of Disconnects. The photovoltaic system disconnecting means shall
consist of not more than six switches or six circuit breakers mounted in a single enclosure, in a
group of separate enclosures, or in or on a switchboard.
(5) Grouping. The photovoltaic system disconnecting means shall be grouped with other
disconnecting means for the system to comply with 690.14(C) (4). A photovoltaic
disconnecting means shall not be required at the photovoltaic module or array location.
(D) Utility-Interactive Inverters Mounted in Not-Readily-Accessible Locations. Utility-interactive
inverters shall be permitted to be mounted on roofs or other exterior areas that are not readily
accessible. These installations shall comply with (1) through (4):
(1)
A direct-current photovoltaic disconnecting means shall be mounted within sight of or
in the inverter.
(2)
An alternating-current disconnecting means shall be mounted within sight of or in the
inverter.
(3)
The alternating-current output conductors from the inverter and an additional
alternating-current disconnecting means for the inverter shall comply with 690.14(C) (1).
(4)
A plaque shall be installed in accordance with 705.10.
690.15 Disconnection of Photovoltaic Equipment.
Means shall be provided to disconnect equipment, such as inverters, batteries, charge
controllers, and the like, from all ungrounded conductors of all sources. If the equipment is
energized from more than one source, the disconnecting means shall be grouped and
identified.
A single disconnecting means in accordance with 690.17 shall be permitted for the combined
ac output of one or more inverters or ac modules in an interactive system.
PEOPLE ● PRIDE ● PROGRESS ● PARTNERSHIPS
700 North Tryon Street • Charlotte, North Carolina 28202 • Phone (704) 336-3545• Fax (704) 336-3839
www.meckpermit.com
MECKLENBURG COUNTY
Land Use & Environmental Services Agency
Code Enforcement
Page 7 of 8
690.16 Fuses.
Disconnecting means shall be provided to disconnect a fuse from all sources of supply if the
fuse is energized from both directions and is accessible to other than qualified persons. Such a
fuse in a photovoltaic source circuit shall be capable of being disconnected independently of
fuses in other photovoltaic source circuits.
690.17 Switch or Circuit Breaker.
The disconnecting means for ungrounded conductors shall consist of a manually operable
switch (es) or circuit breaker(s) complying with all of the following requirements:
(1)
(2)
(3)
(4)
that is
Located where readily accessible
Externally operable without exposing the operator to contact with live parts
Plainly indicating whether in the open or closed position
Having an interrupting rating sufficient for the nominal circuit voltage and the current
available at the line terminals of the equipment
Where all terminals of the disconnecting means may be energized in the open position, a
warning sign shall be mounted on or adjacent to the disconnecting means. The sign shall be
clearly legible and have the following words or equivalent:
WARNING
ELECTRIC SHOCK HAZARD.
DO NOT TOUCH TERMINALS. TERMINALS
ON BOTH THE LINE AND
LOAD SIDES MAY BE ENERGIZED
IN THE OPEN POSITION.
Exception: A connector shall be permitted to be used as an ac or a dc disconnecting means,
provided that it complies with the requirements of 690.33 and is listed and identified for the
use.
690.18 Installation and Service of an Array.
Open circuiting, short circuiting, or opaque covering shall be used to disable an array or
portions of an array for installation and service.
FPN: Photovoltaic modules are energized while exposed to light. Installation, replacement, or
servicing of array components while a module(s) is irradiated may expose persons to electric
shock.
PEOPLE ● PRIDE ● PROGRESS ● PARTNERSHIPS
700 North Tryon Street • Charlotte, North Carolina 28202 • Phone (704) 336-3545• Fax (704) 336-3839
www.meckpermit.com
MECKLENBURG COUNTY
Land Use & Environmental Services Agency
Code Enforcement
Page 8 of 8
705.10 Directory.
A permanent plaque or directory, denoting all electric power sources on or in the premises,
shall be installed at each service equipment location and at locations of all electric power
production sources capable of being interconnected.
Exception: Installations with large numbers of power production sources shall be permitted to
be designated by groups.
10. Can a load center be mounted in a horizontal position?
The term “horizontal” can be interpreted two ways:
1) Rotated on the wall 90 degrees
2) Mounted on the ceiling or on or under the floor
Code Reference: 240.33 and 240.81
The issue over horizontal mounting goes back to the 1925 NEC. The specific issue was to
prohibit fused switches from being mounted on the ceiling (under a floor) where the constant
vibration from the floor traffic could cause the fuse to dislodge from a fuse clip and drop
against the enclosure creating a ground fault.
The language in 240.33 was changed in the 2002 NEC with a substantiation that revolved
around rotating the enclosure 90 degrees not from wall to ceiling or floor.
240.33 Vertical Position.
Enclosures for over current devices shall be mounted in a vertical position unless that is shown
to be impracticable. Circuit breaker enclosures shall be permitted to be installed horizontally
where the circuit breaker is installed in accordance with 240.81. Listed busway plug-in units
shall be permitted to be mounted in orientations corresponding to the busway mounting
position.
240.81 Indicating.
Circuit breakers shall clearly indicate whether they are in the open “off” or closed “on”
position. Where circuit breaker handles are operated vertically rather than rotationally or
horizontally, the “up” position of the handle shall be the “on” position.
Typically, mounting a panel board horizontally will cause a number of the circuit
breakers (1/2) to have their handles in the up position when they are off, which is
not allowed.
PEOPLE ● PRIDE ● PROGRESS ● PARTNERSHIPS
700 North Tryon Street • Charlotte, North Carolina 28202 • Phone (704) 336-3545• Fax (704) 336-3839
www.meckpermit.com