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Grounding is the
intentional connection of
a current-carrying
conductor to the earth.
Reasons For Grounding
• Limit voltage surges.
• Provide a ground reference point.
• Facilitate the operation of overcurrent devices.
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Bonding is the joining
together of metal parts
that are not intended to
carry current during
normal operation.
Reasons For Bonding
• To establish an effective path for fault current.
• Bonding limits the touch voltage when noncurrent-carrying metal parts are inadvertently
energized by a ground fault.
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Ground-fault
current path is
required to
ensure that
overcurrent
devices operate
to open the
circuit.
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A ground-fault is an unintentional connection
between an ungrounded conductor and metallic
enclosures, raceways, equipment, or earth.
Ungrounded
conductor
Ground
fault
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The ground-fault
circuit interrupter
(GFCI) senses small
ground-fault currents.
GFCIs compare the amount of current
in the ungrounded (hot) conductor and
the grounded (neutral) conductor.
Whenever the ground-fault current difference
exceeds approximately 5 mA, the device
automatically opens the circuit to the receptacle.
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An arc-fault is an
unintentional arcing
condition in a circuit.
The arc-fault circuit
interrupter (AFCI)
protects against fires
caused by arcing faults.
1-7
A series arc fault
occurs when the
conductor in series
with the load breaks.
Parallel arcing faults
can occur as a result of a
short across two
conductors or a ground
fault.
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AFCIs are designed to recognize when arc
faults occur and automatically shut the circuit
down before it becomes a fire hazard.
1-9
Electrical lockout involves
removing the source of electric
power and installing a lock, which
prevents the power from being
turned ON.
Electrical tagout involves of
placing a danger tag on the
source of electric power, which
indicates that the equipment may
not be operated until the danger
tag is removed.
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Verification Of Voltage Isolation
Ensure that your
voltmeter is working
properly by performing
the live-dead-live
check.
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Occupational Safety and Health
Administration: OSHA’s goal is to
ensure that employers provide employees
a workplace that is free of hazards.
The National Electrical Code (NEC)
comprises a set of rules intended to
provide a safe installation of
electrical wiring and equipment.
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The National Fire Protection
Association (NFPA) develops codes
governing construction practices in the
building and electrical trades.
In accordance with OSHA safety
standards, a nationally recognized
testing laboratory (such as
Underwriters Laboratories) must test
electrical products for conformity to
national codes and standards.
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The National Electrical
Manufacturers Association
(NEMA) is a group that defines and
recommends safety standards for
electrical equipment.
NEMA type 1 enclosure
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