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conductor, is grounded. In an ordinary low-voltage circuit, the white or gray wire is
grounded at the generator or transformer and at the building s service entrance.‟
An equipment ground helps protect the equipment operator. It furnishes a
second path for the current to pass through from the tool or machine to the ground.

This additional ground safeguards the operator if a malfunction causes the tool s‟
metal frame to become energized. The resulting flow of current may activate the
circuit protection devices.

4) Circuit protection devices limit or stop the flow of current automatically in
the event of a ground fault, overload, or short circuit in the wiring system. Well-
known examples of these devices are fuses, circuit breakers, ground-fault circuit
interrupters, and arc-fault circuit interrupters (Figure 14.8).

Figure 14.8 – Circuit protection devices

Fuses and circuit breakers open or break the circuit automatically when too
much current flows through them. When that happens, fuses melt and circuit breakers
trip the circuit open. Fuses and circuit breakers are designed to protect conductors
and equipment. They prevent wires and other components from overheating and open
the circuit when there is a risk of a ground fault.
Ground-fault circuit interrupters, or GFCIs, are used in wet locations,
construction sites, and other high-risk areas. These devices interrupt the flow of
electricity within as little as 1/40 of a second to prevent electrocution. GFCIs
compare the amount of current going into electric equipment with the amount of
current returning from it along the circuit conductors. If the difference exceeds 5
milliamperes, the device automatically shuts off the electric power.
Arc-fault devices provide protection from the effects of arc-faults by
recognizing characteristics unique to arcing and by functioning to de-energize the
circuit when an arc-fault is detected.
5) Electrical accidents are largely preventable through safe work practices.
Examples of these practices include the following:
 de-energizing electric equipment before inspection or repair;

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