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What electrical hazards does a Ground Fault Circuit Interrupter (GFCI) NOT protect against?
Monday, July 9, 2018
The Ground Fault Circuit Interrupter (GFCI) is an important safety device required for electrical circuits in wet areas of a home. GFCI's protect against an electrical shock by tripping within a fraction of a second whenever 6 milliamps or more of the current leaving on the hot wire of a circuit is not returning on the neutral wire. The current that has gone astray is called a “ground fault,” which could cause a shock or even electrocution of a person if the current is flowing through their body, so the GFCI “interrupts” the circuit when this occurs.
A GFCI can be in a receptacle, like in the photo above, integral with a circuit breaker in an electric panel, or installed as a “dead front” GFCI in electrical box by itself.
But here are five unsafe situations that GFCIs do not protect you from:
1) A GFCI does not trip when a person contacts both the hot and neutral wires of a circuit and all the current flows through their body. It does not recognize the problem because no current is leaking from the circuit. While this sounds like a farfetched scenario, we have on numerous occasions come across bare “live” wires at the end of an electrical cable laying half-buried in the insulation in an attic. Inadvertently putting a hand down of the wires while crawling in the attic would be an example of how this situation could happen.
2) Although a GFCI is required to trip within 25 milliseconds, it does not reduce the magnitude of the current. You will still receive a shock for the brief time that it takes for it to shut off the circuit.
3) A GFCI receptacle does not provide protection against too much current flowing through the wires. This is called over-current protection and is provided by a circuit breaker in the electric panel. But GFCI circuit breakers in the electric panel provide both ground fault and over-current protection for the circuits they serve.
4) It does not protect against what is called a “solid short,” where all the current is diverted from its intended route. This could occur between a hot and neutral wire or between two hot wires in a 240-volt circuit. Protection for this problem is provided by circuit breakers.
5) A GFCI does not recognize arc faults, that are typically caused by frayed appliance and extension cords. The hot sparks created by an arc fault have caused numerous house fires. Arc Fault Circuit Interrupters (AFCIs) have been required as part of circuit breakers serving bedrooms for many years, and the requirement has been expanded to most household circuits recently.
None of this is intended to take away from the value of GFCIs for home electrical safety. It’s just that there’s some things they do, and some things they don’t.
Also see our blog post Are Ground Fault Circuit Interrupters (GFCIs) really necessary and worth the trouble?
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Here’s links to a collection of our other blog posts about AFCI and GFCI RECEPTACLES AND CIRCUIT BREAKERS:
• Does a septic pump or sump pump require a GFCI-receptacle?
• What is the difference between what trips a GFCI (ground fault) receptacle and a circuit breaker?
• What is the code requirement for GFCI protection for receptacles near a wet bar sink?
• When was GFCI-protection for kitchen dishwasher receptacle outlet first required?
• When did arc fault circuit interrupter (AFCI) breakers first become required?
• Does a washing machine receptacle outlet require GFCI protection?
• My spa tub stopped working. What's wrong?
• How do I identify a combination AFCI (CAFCI) circuit breaker?
• What does "listed and labeled" mean for an electrical component?
• What is the difference between GFCI and AFCI circuit breakers?
• Where are GFCI receptacle outlets required?
• When were GFCI receptacle outlets first required?
• What happens when you press the "TEST" button on a circuit breaker in an electric panel?
• What is the difference between the electric service to a mobile home and a site built home?
• Why is there a wall switch next to the furnace or indoor unit of the air conditioner in the garage?
• What is a Dual Function Circuit Interrupter (DFCI)?
• How I can tell if a receptacle outlet is tamper resistant?
• What is the difference between a Combination Arc Fault Circuit Interrupter (CAFCI) and an Arc Fault Circuit Interrupter (AFCI) circuit breaker?
• What is the difference between "grounded" and "grounding" electrical conductors?
• What does it mean when a wire is "overstripped" at a circuit breaker?
• Why is there a GFCI breaker in the electric panel for the bathroom shower light and exhaust fan?
• What is the switch on the wall with two pushbuttons?
• How far apart should kitchen counter receptacles be spaced?
• How far above a kitchen countertop do electrical outlets have to be?
• How is it possible to provide both GFCI (Ground Fault Circuit Interrupter) and CAFCI (Combination Arc Fault Circuit Interrupter) protection for kitchen and laundry circuits?
• My bathroom electric receptacle/outlet is dead and there are no tripped breakers in the electric panel. What's wrong?
• My GFCI reset button is hard to push and won't reset. What's wrong?
• Why do some breakers in my electric panel have a "TEST" button on them?
Visit our AFCI AND GFCI page for other related blog posts on this subject, or go to the INDEX for a complete listing of all our articles.
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