A Ground Fault Circuit Interrupter, commonly called a GFI or GFCI, is most commonly installed on exterior outlets, or in areas where there is a water source (bathroom or kitchen sink) near the outlet. They are easily identified by two buttons in the middle of the receptacle, sometimes the buttons are colored.
GFCI units are designed to protect the users of electrical appliances from electrocution because of hazardous ground faults or short circuits, by automatically turning off electricity when a fault is detected.
GFCI wiring regulations only apply to newer wiring installations and new construction.
Older homes are not obliged to install GFI’s unless they are been rewired or a new outlet is being added in a location that would require a GFCI in a new house.
GFCI’s interrupt the electrical supply faster than a breaker or fuse can, responding in milliseconds. There are two types of GFCI available. One replaces a standard circuit breaker with a special GFCI circuit breaker, identified by a test button on the face of the breaker. The other is a GFI protected outlet that takes the place of a regular outlet and is easily identified by its test and reset buttons.
When installed correctly, a “GFCI outlet” will protect all the outlets “down line”on the same wiring circuit.
NOTE: Grounded type (three prong) outlets may not be substituted for ungrounded (two prong) outlets unless a ground wire is connected. An exception to this rule is allowed (National electric code for older wiring applications) when the outlet is protected by a ground fault interrupter (GFI).