Electrical in General Industry
Safety & Health Consultation
ELECTRICAL [1910.301 – 399]
29CFR 1910 SUBPARTS
303(b)(2)
698
GROUNDING PERMANENT AND EFFECTIVE
305(b)(1)(ii)
496
FLEXIBLE CORD STRAIN RELIEF
305(g)(2)(iii)
SUBPART S
PROPER INSTALLATION & USE OF EQUIPMENT
487
FLEXIBLE CORDS USED AS FIXED WIRING
305(g)(1)(iv)(A)
423
PULL/JUNCTION BOX COVERS
305(b)(2)(i)
387
2
NUMBER OF SERIOUS VIOLATIONS – FY 2014
Electrical Terminology
•
•
•
•
Current – the movement of electrical charge
Resistance – opposition to current flow
Voltage – a measure of electrical force
Conductors – substances, such as metals, that have
little resistance to electricity
• Insulators – substances, such as wood, rubber,
glass, and bakelite, that have high resistance to
electricity
• Grounding – a conductive connection to the earth
which acts as a protective measure
Safety & Health Consultation
Electrical Utilization Systems
• Electrical installations and utilization equipment
installed or used within or on buildings, structures
and other premises:
–
–
–
–
–
–
–
–
Yards
Carnivals
Parking and other lots
Mobile homes
Recreational vehicles
Industrial substations
Conductors that connect the installations to a supply of electricity
Other outside conductors on the premises
Safety & Health Consultation
1910.302(a)
Electrical Hazards
What’s the first thing that comes to mind?
Direct: Electrocution
Shock
Burns
Fire
Explosions
Arc Blast / Arc Flash
Safety & Health Consultation
Reaction: Falls
Shock & Electrocution Levels
• 1/1000 ampere – Perception level
• 1/100 ampere – Muscular contraction
• 1/10 ampere – Electrocution
Overcurrent devices
Does NOT trip until at least
15 amperes
Safety & Health Consultation
Question???
Are over current devices used to protect people?
No, they protect equipment and property
Safety & Health Consultation
Electrical Protective Devices
• These devices shut off electricity flow in the event
of an overload or ground-fault in the circuit
• Include fuses, circuit breakers, and ground-fault
circuit-interrupters (GFCI’s)
• Fuses and circuit breakers are overcurrent devices
– When there is too much current:
• Fuses melt
• Circuit breakers trip open
Safety & Health Consultation
Electrical Shock
• Received when current passes
through the body
• Severity of the shock depends on:
– Path of current through the body
– Amount of current flowing through
the body
– Length of time the body is in the
circuit
• LOW VOLTAGE DOES NOT
MEAN LOW HAZARD
Safety & Health Consultation
Dangers of Electrical Shock
• Currents greater than 75 mA*
can cause ventricular fibrillation
(rapid, ineffective heartbeat)
• Will cause death in a few
minutes unless a defibrillator is
used
• 75 mA is not much current – a
small power drill uses 30 times
as much
Defibrillator in use
* mA = milliampere = 1/1,000 of an ampere
Safety & Health Consultation
How is an electrical shock received?
• When two wires have different potential
differences (voltages), current will flow if they are
connected together
– In most household wiring, the black wires are at
110 volts relative to ground
– The white wires are at zero volts because they are
connected to ground
• If you come into contact with an energized (live)
black wire, and you are also in contact with the
white grounded wire, current will pass through
your body and YOU WILL RECEIVE A SHOCK
Safety & Health Consultation
How is an electrical shock received?
• If you are in contact with an energized wire or any
energized electrical component, and also with any
grounded object, YOU WILL RECEIVE A
SHOCK
• You can even receive a shock when you are not in
contact with a ground
– If you contact both wires of a 240-volt cable, YOU
WILL RECEIVE A SHOCK and possibly be
electrocuted
Safety & Health Consultation
Electrical Hazards
Remember, if it’s an electrocution, it’s a
FATALITY!
Safety & Health Consultation
Falls
• Electric shock can also
cause indirect or
secondary injuries
• Workers in elevated
locations who experience
a shock can fall, resulting
in serious injury or death
Safety & Health Consultation
Electrical Burns
• Most common shock-related,
nonfatal injury
• Occurs when you touch
electrical wiring or equipment
that is improperly used or
maintained
• Typically occurs on the hands
• Very serious injury that needs
immediate attention
Safety & Health Consultation
Fires
Safety & Health Consultation
Inadequate Wiring Hazards
• A hazard exists when a conductor is too small to
safely carry the current
• Example: using a portable tool with an extension cord
that has a wire too small for the tool
– The tool will draw more current than the cord can handle,
causing overheating and a possible fire without tripping
the circuit breaker
– The circuit breaker could be the right size for the circuit
but not for the smaller-wire extension cord
Safety & Health Consultation
Inadequate Wiring Hazards
Note: The larger the gauge number, the smaller the wire.
Safety & Health Consultation
Overload Hazards
• If too many devices are
plugged into a circuit, the
current will heat the wires to
a very high temperature,
which may cause a fire
• If the wire insulation melts,
arcing may occur and cause a
fire in the area where the
overload exists, even inside a
wall
Safety & Health Consultation
Explosions
Arc Blast/Arc Flash
Safety & Health Consultation
“I can work it live because
I’m Qualified!”
Safety & Health Consultation
“The standards require
that all work shall be done
de-energized!”
1910.331-335
NFPA 70E
Safety & Health Consultation
Explosions
80% of electrically related
accidents, incidents, and fatalities
among Qualified Workers
Caused by
Arc Blast/Arc Flash
Safety & Health Consultation
Ground-Fault Circuit Interrupter
• This device protects you from dangerous
shock
• The GFCI detects a difference in current
between the black and white circuit wires
(This could happen when electrical
equipment is not working correctly,
causing current “leakage” – known as a
ground fault.)
• If a ground fault is detected, the GFCI can
shut off electricity flow in as little as 1/40
of a second, protecting you from a
dangerous shock
Safety & Health Consultation
Grounding Hazards
• Some of the most frequently violated OSHA standards
• Metal parts of an electrical wiring system that we touch
(switch plates, ceiling light fixtures, conduit, etc.) should
be at zero volts relative to ground
• Housings of motors, appliances or tools that are plugged
into improperly grounded circuits may become energized
• If you come into contact with an improperly grounded
electrical device, YOU WILL BE SHOCKED
Safety & Health Consultation
Overhead Powerline Hazards
• Most people don’t realize that
overhead powerlines are usually not
insulated
• Powerline workers need special
training and personal protective
equipment (PPE) to work safely
• Do not use metal ladders – instead,
use fiberglass ladders
• Beware of powerlines when you work
with ladders and scaffolding
Safety & Health Consultation
Some Examples of OSHA
Electrical Requirements . . . .
Safety & Health Consultation
Approval
• Approval. The conductors and equipment
required or permitted by this subpart shall
be acceptable only if approved
Safety & Health Consultation
1910.303(a)
Examination, Installation, and Use
• Employer Obligation
– Electrical equipment must
be free from recognized
hazards that are likely to
cause death or serious
physical harm to
employees:
• Cables exposed to sharp
edges
• Splices
• Bare conductors
Safety & Health Consultation
1910.303(b)(1)
Examination, Installation, and Use
• Examination. Safety of equipment shall
determined using the following considerations:
– Suitability of equipment for an identified purpose may be
evidenced by listing or labeling for that identified purpose
Safety & Health Consultation
1910.303(b)(2)
Mechanical Execution of Work
• Equipment shall be installed in a neat
workmanlike manner
Safety & Health Consultation
1910.303(b)(7)
Mechanical Execution of Work
• Unused openings shall be effectively closed to
afford protection substantially equivalent to the
wall of the equipment.
Safety & Health Consultation
1910.303(b)(7)(i)
Equipment Marking
• Electrical equipment may not be used unless the
manufacturer's name, trademark, or other
descriptive marking by which the organization
responsible for the product may be identified is
placed on the equipment
1910.303(e)(1)
1910.302(e)(1)(i)
Safety & Health Consultation
Equipment Marking
• Other markings shall be provided giving
voltage, current, wattage, or other ratings
as necessary. The marking shall be of
sufficient durability to withstand the
environment involved
Safety & Health Consultation
480 V
1910.303(e)(1)(ii)
Identification of Disconnecting
Means and Circuits
• Each disconnecting means (dm) legibly
marked to indicate its purpose
– (Unless so arranged so the purpose is evident)
• A dm is a switch used to disconnect the
conductors of a circuit from the source of
current
Disconnect switch for
motor number 3
Safety & Health Consultation
1910.303(f)(1)
Identification of Disconnecting
Means and Circuits
• Each service, feeder, and branch circuit, at its
dm or overcurrent device, legibly and durably
marked to indicate its purpose
• Switches and circuit breakers must be clearly
labeled to indicate its circuit’s function
Circuit breaker for motors
1,2,3, and 4
1910.303(f)(2)
Example of properly labeled
electric service: motors,
disconnects and breakers
Safety & Health Consultation
Identification of Disconnecting
Means and Circuits
• Disconnecting means shall be capable of
being locked in the open position.
Safety & Health Consultation
1910.303(f)(4)
Working Space about Electric
Equipment
• Sufficient access and
working space around all
electrical equipment,
provided & maintained to
provide ready and safe
operation and maintenance
• Not used for storage
• If located in aisle or general
open area, working space
shall be suitably guarded
Safety & Health Consultation
1910.303(g)
TABLE S-1 - WORKING CLEARANCES
____________________________________________
Nominal voltage
Minimum clear distance
to ground
for condition (2)(ft.)
__________________________________________
(a)
(b)
(c)
________________________________________
0-150 .........…
(1)3
(1)3
3
151-600 .......…
(1)3
3 1/2
4
________________________________________
Footnote(1) Minimum clear distances may be 2 feet 6
inches for installations built prior to April 16, 1981.
Safety & Health Consultation
Working Space about Electric
Equipment
If the nominal voltage to ground is from 151 - 600 V:
Safety & Health Consultation
1910.303(g)(1)(i)
Equipment Illumination
• Illumination provided for
all working spaces about
service equipment,
switchboards, panelboards, and motor control
centers installed indoors.
Safety & Health Consultation
1910.303(g)(1)(v)
Headroom
6'3"
Safety & Health Consultation
• The minimum headroom
of working spaces about
service equipment,
switchboards, panelboards, or motor control
centers shall be 6 feet 3
inches
1910.303(g)(1)(vi)
Guarding of Live Parts
• Live parts of electric equipment operating at
50 volts or more must be guarded.
Safety & Health Consultation
1910.303(g)(2)(i)
Identification of Conductors
• A conductor used as a grounded
conductor shall be identifiable and
distinguishable from all other
conductors.
• A conductor used as an equipment
grounding conductor shall be
identifiable and distinguishable
from all other conductors
Safety & Health Consultation
1910.304(a)(1)
Identification of Conductors
• Grounded conductor and equipment grounding
conductors marked or color coated so that
employees can i.d. and tell apart
• Grounded conductor is an energized circuit
(conductor that is connected to earth through the
system ground) Commonly referred to as the neutral
Safety & Health Consultation
Grounding Conductors
• Equipment grounding conductor acts as a
safeguard against insulation failure or faults in the
other circuit conductors
• Not an energized conductor under normal
conditions.
• Energized if a leak or fault in the normal current path
• Directs current back to the source
• Enabling fuses or circuit breakers to operate
Safety & Health Consultation
Identification of Conductors
• Grounded conductor i.d. and distinguished from other
conductors w/ white or gray
• Equipment grounding conductor i.d. and distinguished
w/green, green w/ yellow stripes, or bare
Safety & Health Consultation
Use and Identification of Grounded and
Grounding Conductors
• No grounded conductor may be attached to any
terminal or lead so as to reverse polarity
Correct polarity between the
ungrounded (hot) conductor, the
grounded (neutral) conductor,
and the grounding conductor
must be maintained
1910.304(a)(2)
Safety & Health Consultation
Safety & Health Consultation
Branch Circuits
• Safety factor of 20%
TABLE S–4. — Maximum Cord- and Plug- Connected Load to Receptacle
Circuit rating
(amperes)
15 or 20
20
30
Safety & Health Consultation
Receptacle
rating
(amperes)
15
20
30
Maximum
load
(amperes)
12
16
24
1910.304(b)(4)(ii)(B)
Disconnecting Means
• General. Means provided to disconnect all conductors in
a building from the service-entrance conductors.
• The disconnecting means shall plainly indicate whether
it is in the open or closed position
• Installed at a readily accessible location
1000kV
Safety & Health Consultation
1910.304(e)(1)
Services over 600 volts, nominal
• Guarded to make them accessible only to qualified
persons
• Signs warning of high voltage shall be posted where
other than qualified employees might come in
contact with live parts
1000kV
1910.304(e)(2)
Safety
& Health Consultation
Danger
Overcurrent Protection
• 600 volts or less:
– Overcurrent devices readily accessible to each employee
– May not be located where they will be exposed to physical
damage nor in the vicinity of easily ignitable material
– Fuses and circuit breakers located or shielded that
employees will not be burned or otherwise injured by their
operation
1000kV
Safety
& Health Consultation
Danger
1910.304(f)
Circuit Breakers
• Circuit breakers shall clearly indicate whether
they are in the open (off) or closed (on)
position
1000kV
Safety
& Health Consultation
Danger
1910.304(f)(1)(vi)
Grounding
• The path to ground from
circuits, equipment, and
enclosures must be
permanent and continuous
• Violation shown here is an
extension cord with a
missing grounding prong
Safety & Health Consultation
1910.304(g)(5)
Grounding
• Required to protect employees against:
– Shock
– Safeguard against fire
– Protect equipment from damage
Safety & Health Consultation
Grounding
• There are two kinds of grounding:
– Electrical circuit or system grounding
– Electrical equipment grounding
Safety & Health Consultation
Electrical System Grounding
• One conductor of the circuit is
intentionally grounded to earth
• Protects circuit from lightning, or other high
voltage contact
• Stabilizes the voltage in the system so “expected
voltage levels” are not exceeded under normal
conditions
Safety & Health Consultation
Equipment Grounding
• All metal frames & enclosures of equipment are
grounded by a permanent connection or bond
• The equipment grounding conductor provides a path
for dangerous fault current to return to the system
ground at the supply source should a fault occur
Safety & Health Consultation
Hand-Held Electric Tools
• Hand-held electric tools pose a
potential danger because they make
continuous good contact with the
hand
• To protect you from shock, burns,
and electrocution, tools must:
– Have a three-wire cord with ground
and be plugged into a grounded
receptacle, or
– Be double insulated, or
– Be powered by a low-voltage isolation
transformer
Safety & Health Consultation
1910.304(g)(6)(vi)(C)(3)
Safety & Health Consultation
Note: Properly bonded conduit and associated metal enclosures can
also serve as a grounding conductor.
Safety & Health Consultation
Guarding of Live Parts
• Must guard live parts of electric
equipment operating at 50 volts or
more against accidental contact by:
– Approved cabinets/enclosures, or
– Location or permanent partitions
making them accessible only to
qualified persons, or
– Elevation of 8 ft. or more above the
floor or working surface
• Mark entrances to guarded locations
with conspicuous warning signs
Safety & Health Consultation
1910.303(g)(2)(i)
Guarding of Live Parts
• Other forms of approved enclosures, or by any of the
following means by:
– Location in a room, vault, accessible only to qualified persons
– Permanent, substantial partitions or screens
– By location on a suitable balcony or platform as to exclude unqualified
persons
– Elevation of 8 feet or more above the floor or other
working surface
1910.303(g)(2)
Safety & Health Consultation
Guarding of Live Parts
• Must enclose or guard
electric equipment in
locations where it would
be exposed to physical
damage
Violation shown here
is physical damage to
conduit
Safety & Health Consultation
1910.303(g)(2)(ii)
Wiring in Ducts
• No wiring systems of any type installed in ducts
used to transport dust, loose stock or flammable
vapors
Safety & Health Consultation
1910.305(a)(1)(ii)
Temporary Wiring
• All lamps for general illumination shall be protected
from accidental contact or breakage by a suitable
fixture or lampholder with a guard. Brass shell,
paper-lined sockets, or other metal-cased sockets
may not be used unless the shell is grounded.
1910.305(a)(2)(ix)
Safety & Health Consultation
Temporary Wiring
• Flexible cords and cables shall be protected from
accidental damage
• Sharp corners and projections shall be avoided.
• Where passing through doorways or other pinch
points, flexible cords and cables shall be provided
with protection to avoid damage
1910.305(a)(2)(x)
Safety & Health Consultation
Conductors Entering Boxes,
Cabinets or Fittings
• Conductors can be damaged if they
rub against the sharp edges of
cabinets, boxes, or fittings
• Where they enter they must be
protected by some type of clamp or
rubber grommet
• The device used must close the hole
through which the conductor passes
as well as provide protection from
abrasion
Safety & Health Consultation
1910.305(b)(1)
Conductors Entering Boxes,
Cabinets or Fittings
• All pull boxes, junction boxes and fittings must be
provided with covers identified for the purpose
• If covers are metal they must be grounded.
• Each outlet box must have a cover, faceplate or fixture
canopy
1910.305(b)(2)(i)
Safety & Health Consultation
Use of Flexible Cords
• Where passing through doorways or other
pinch points, flexible cords and cables shall
be provided with protection to avoid
damage
1910.305(a)(2)(x)
Safety & Health Consultation
Use of Flexible Cords
• More vulnerable than fixed wiring
• Do not use if one of the recognized
wiring methods can be used instead
• Flexible cords can be damaged by:
–
–
–
–
–
Aging
Door or window edges
Staples or fastenings
Abrasion from adjacent materials
Activities in the area
• Improper use of flexible cords can
cause shocks, burns or fire
Safety & Health Consultation
1910.305(g)
Permissible Uses of Flexible Cords
Examples
Pendant, or
Fixture Wiring
Portable lamps,
tools or appliances
Safety & Health Consultation
Stationary equipmentto facilitate interchange
1910.305(g)(1)(ii)
Prohibited Uses of Flexible Cords
Examples
Substitute for
fixed wiring
Run through walls,
ceilings, floors,
doors, or windows
Safety & Health Consultation
Concealed behind
or attached to
building surfaces
1910.305(g)(1)
Flexible Cords
• Flexible cords must be connected to devices and
fittings.
– Strain relief must be provided to prevent pull from
being directly transmitted to joints or terminal
screws.
Safety & Health Consultation
1910.305(g)(2)(iii)
Electrical Safety
Related Work Practices
1910.331 - 335
Safety & Health Consultation
80% of electrically related
accidents, incidents, and fatalities
among Qualified Workers
Caused by
Arc Blast /Arc Flash
Safety & Health Consultation
What electrical hazard is responsible for
nearly 80% of the accidents, incidents, and
fatalities among Unqualified Workers?
Electrocution
Usually associated with a lack of
Equipment Grounding!
Safety & Health Consultation
Electrical Safety
Related Work Practices
• 1910.331(a)(1) Premise Wiring. Installations of electric
conductors and equipment within or on buildings or other
structures, and on other premises such as yards, carnival
parking, and other lots, and industrial substations;
• 1910.399 Equipment. A general term including material,
fittings, devices, appliances, fixtures, apparatus, and the
like, used as part of, or in connection with an electrical
installation.
Safety & Health Consultation
Does this standard apply to a technician
working at a repair center, diagnosing /
troubleshooting and repairing:
Microwave ovens? Yes
TV’s and VCR’s? Yes
Computers? Yes
Lamps? Yes
Anything electrical? Yes
Safety & Health Consultation
Protection by Electrical
Installation Standards
1 – Avoid contact
a – Guard
b – Insulate
c – Elevate
2 – Grounding
(Equipment Ground)
3 - GFCI
Safety & Health Consultation
Safety Related Work Practices
• Covers:
• Qualified persons (those who have training in avoiding
the electrical hazards)
• Unqualified persons (those with little or no such
training)
1910.331 - 335
Safety & Health Consultation
Safety Related Work Practices
•
Qualified persons: (i.e. those permitted to work on or near
exposed energized parts) shall, at a minimum, be trained in
and familiar with the following:
– The skills and techniques necessary to distinguish exposed live
parts from other parts of electric equipment
– The skills and techniques necessary to determine the nominal
voltage of exposed live parts
1910.331 - 335
Safety & Health Consultation
Unqualified Persons
• .332(a) Training requirements apply to employees who
face the risk of shock not reduced to a safe level by
installation requirements of .301 - .308 Subpart S
• (b)(2) also trained in electrical safe work practices not
addressed here but which is necessary for their safety
• .334 Use of portable equipment
Safety & Health Consultation
Unqualified Persons
• Another way to say this is, unqualified workers:
• Are normally protected by the installation requirements by
Subpart S
However
• If their work exposes them to electrical hazards which would
otherwise be protected according to Subpart S, they must be
trained.
• Trained to recognize and avoid hazards encountered or likely to
encounter while working.
Safety & Health Consultation
Safety Related Work Practices
• Unqualified person working near overhead lines, the
person and the longest conductive object they may
contact cannot come closer to any energized
overhead line than the following distances:
– For voltages to ground 50kV or below - 10 feet
– For voltages to ground over 50kV - 10 feet plus 4 inches
for every 10kV over 50kV
1910.331 - 335
Safety & Health Consultation
Safety Related Work Practices
• While any employee is exposed to contact with
parts of fixed electric equipment or circuits
which have been deenergized, the circuits
energizing the parts shall be locked out or
tagged or both*
1910.331 - 335
Safety & Health Consultation
Use of Portable Equipment
• 1910.334(a) covers:
– Cordsets (extension cords)
– Cord and plug connected equipment
– For unqualified as well as qualified workers
Safety & Health Consultation
Use of Portable Equipment
• 1910.334(a)
– Don’t abuse, damage, or use for a rope (a)(1)
In other words don’t use the cord to
raise or lower equipment
Safety & Health Consultation
This standard addresses the root cause
factors of these recurring hazards….
As a result, we will have a positive and
lasting effect on safety and ultimately
eradicate recurring hazards.
Safety & Health Consultation
Use of Portable Equipment
• 1910.334
– (a)(1) Don’t abuse damage, or use as a rope.
– (a)(2) Visually inspect before use.
– (a)(2) Loose parts, deformed/bent pins or
blades, missing pins or blades, (GROUND
PIN).
Safety & Health Consultation
Use of Portable Equipment
• 1910.334
– (a)(2) Damage to outer jacket, evidence of
damage, pinched /crushed.
– (a)(2)(ii) Shall be removed from service and not
used until repaired
Safety & Health Consultation
Use of Portable Equipment
The purpose of the equipment
grounding conductor is to …
Prevent Electrocution
In the event of a fault or short circuit in
the tool or equipment
Safety & Health Consultation
Safety Related Work Practices
• Portable electric equipment and
flexible cords used in highly
conductive work locations, or in job
locations where employees are likely
to contact water or conductive liquids,
shall be approved for those locations
1910.331 - 335
Safety & Health Consultation
Safety Related Work Practices
• Conductive articles of jewelry and clothing (such a
watch bands, bracelets, rings, key chains,
necklaces, etc...) may not be worn if they might
contact exposed energized parts
1910.331 - 335
Safety & Health Consultation
Clues that Electrical Hazards Exist
• Tripped circuit breakers or blown fuses
• Warm tools, wires, cords, connections, or
junction boxes
• GFCI that shuts off a circuit
• Worn or frayed insulation around wire or
connection
Safety & Health Consultation
Training
Train employees working with electric
equipment in safe work practices, including:
• Deenergizing electric equipment before inspecting
or making repairs
• Using electric tools that are in good repair
• Using good judgment when working near
energized lines
• Using appropriate protective equipment
Safety & Health Consultation
Summary
Hazards
•
•
•
•
•
•
•
•
•
Inadequate wiring
Exposed electrical parts
Wires with bad insulation
Ungrounded electrical
systems and tools
Overloaded circuits
Damaged power tools and
equipment
Using the wrong PPE and
tools
Overhead powerlines
All hazards are made worse
in wet conditions
Safety & Health Consultation
Protective Measures
• Proper grounding
• Using GFCI’s
• Using fuses and circuit
breakers
• Guarding live parts
• Proper use of flexible
cords
• Training
Your Questions?
Safety & Health Consultation