Ground Fault Circuit Interrupter

Last updated: November 10, 2020

What Does Ground Fault Circuit Interrupter Mean?

A ground fault circuit interrupter (GFCI) is a type of circuit breaker that is designed to quickly shut-off electric power in the event of a ground-fault.

A “ground fault” describes a situation in which there is a break (fault) in the grounding path used to control the flow of electricity to an electrical system or tool. When such a fault occurs, the electrical current may take an alternative path to the ground, which can be potentially fatal if that path causes current to flow through the user. A GFCI’s quick circuit-breaking functions are thus an important way to minimize the risk of harm in the event that a ground-fault occurs.

Safeopedia Explains Ground Fault Circuit Interrupter

Ground-fault circuit interrupters (GFCIs) are a common form of electrical shock protection. Ground-faults are the most common form of electrical shock hazard and can impact any electrical device that has a low-resistance grounding path—occupational and residential alike—which translates to all devices that rely on being plugged into a standard electrical outlet to function.

A GFCI works by comparing the amount of current flowing into a piece of equipment against the amount of current returning from that same piece of equipment. When the amount differs outside of a set range—typically around 5 milliamperes—the GFCI will be tripped, breaking the current. GFCIs are generally incorporated into electrical outlets, or they can be plugged into outlets themselves, as is the case for GFCIs that are built-in to some extension cords.

As ground-faults are the most common source of electrical faults, protection against ground-faults is something that all major OHS authorities and agencies address in their respective electrical protection standards. For example, OSHA standard 1926.404 requires most electrical outlets used on construction sites to be protected by the use of a GFCI. In addition to protecting against shocks, GFCIs can also prevent some electrical fires.

A GFCI does not necessarily provide all of the electrical protection that is required within a given setting. It is meant to protect people, and will not necessarily prevent damage to electrical equipment (e.g. computers), and does not protect against arc faults. Although GFCIs activate quickly in the event of a fault, they are not consistently able to prevent shocks to humans; however, in the event that a human is shocked, they should trip quickly enough to prevent significant harm from occurring.

Since their introduction to the National Electrical Code in 1971, the number of annual electrocutions in the United States has dropped by 83%.


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