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615 Electrical Safety - Hazards and Controls
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Ground Fault Circuit Interrupters (GFCI)

A ground fault circuit interrupter, or GFCI, is an inexpensive life-saver.

Ground Fault Circuit Interrupters (GFCI)
GFIC ground fault circuit interrupter mounted to wall

GFCIs detect any difference in current between the two circuit wires (the black wires and white wires). This difference in current could happen when electrical equipment is not working correctly, causing leakage current. If leakage current (a ground fault) is detected in a GFCI-protected circuit, the GFCI switches off the current in the circuit, protecting you from a dangerous shock.

More important points to remember:

  • GFCIs are set at about 5 mA and are designed to protect workers from electrocution.
  • GFCIs detect the loss of current resulting from leakage through a person who is beginning to be shocked. If this situation occurs, the GFCI switches off the current in the circuit.
  • GFCIs are different from circuit breakers because they detect leakage currents rather than overloads.

Circuits with missing, damaged, or improperly wired GFCIs may allow you to be shocked.

You need to recognize that a circuit improperly protected by a GFCI is a hazard.

Knowledge Check Choose the best answer for the question.

2-7. Ground Fault Circuit Interrupters (GFCIs) detect the loss of current resulting from _____.