WHAT IS A GFCI?
A ground fault circuit interrupter (GFCI) is an electrical device which is designed to protect people from electrical shock in a damp or wet environment. A GFCI can be a receptacle (wall plug outlet) or a circuit breaker (in the main electrical panel). Even though GFCI's have been around since the early "70's", many older homes, even after remodeling, and some newer homes, are constructed without the installation of these important safety devices.
WHAT IS A GROUND FAULT AND WHY IS IT DANGEROUS?
A ground fault in an electrical circuit, extension cord, tool or appliance which permits electrical current to flow from the live wire to ground. Faults usually occur as a result of worn insulation, moisture, tools that have deteriorated from age or abuse and, in some cases, from the three-wire plugs that have been replaced and subsequently wired incorrectly.
Ground faults are very dangerous when a person becomes part of the electrical path or circuit to ground. When electrical current escapes through a faulty connection, it seeks a path to ground. The person touching that connection while standing in a wet or damp environment, or touching a sink or tap, becomes a good path to ground. The electrical current flowing through a person's body to ground can result in serious injury or death. Remember, as little as 25 milliamps can stop a person's heart.
HOW DOES THE GFCI WORK?
When an appliance is plugged into a GFCI-protection circuit, the electrical current passing through the circuit is carefully monitored by the device. The GFCI almost instantly senses an electrical ground fault. if the current varies by so much as 5 milliamps, the GFCI interrupts the current, stopping the flow of electrical energy before someone can be harmed. It is commonly recommended that GFCI protection be provided at exterior outlets, bathrooms, garages, pools, spas and other areas where wet conditions may create a hazardous situation.
DOESN'T A CIRCUIT BREAKER PROVIDE THAT PROTECION?
No. Fuses or circuit breakers are primarily designed to protect the electrical system wiring and equipment. They will not protect anyone from serious electrical injury during a ground fault. Be cautioned also that GFCI protection is not over-current protection. GFCI's only protect against ground faults - not electrical overloads.
As with any other safety device, the GFCI should be tested periodically. Some manufacturers even include a check sheet for you to keep track of the date when you last tested your GFCI. A test is simple. Just plug in an appliance such as a light or radio into the GFCI-protected circuit. Next, push the "test" button on the receptacle or circuit breaker. If the button pops out and the appliance stops working (there is no electrical power to the receptacle) the GFCI is working properly. If the button does not pop out, or if it does but the appliance keeps functioning, then you should call a licensed electrician to check your GFCI.
The Canadian Building Consulting Group INC. strongly advises against touching or testing any electrical device before careful visual inspection to make sure there are no exposed wires or broken components. Also, you should ensure that you are standing on a safe, dry location. NEVER TOUCH THE WIRES THAT LEAD FROM THE HOUSE WIRING TO THE RECEPTACLE. If you are in any doubt about the serviceability of any electrical system, on your house, you should call a qualified, licensed electrician.