How to wire a GFCI circuit.

A GFCI circuit can be wired in three basic configurations.  The first is the using a GFCI circuit breaker.  This breaker will protect all of the receptacles downstream of it.  If installation of a circuit breaker is desired, use this article .  The second type of circuit is using a GFCI receptacles connected to only protect themselves.  The third type of circuit is using the GFCI receptacles wired to protect themselves and all receptacles located downstream of the GFCI.

The GFCI receptacle has a line side and a load side.  Each side has a dark (hot) and light (neutral) terminal.  No matter what configuration is used, incoming power needs to always be connected to the line side of the receptacle.  If the GFCI is being used to protect receptacles downstream, then the outgoing power wires will be connected to load side of the GFCI.  If the GFCI is only used to protect that particular receptacle, the outgoing power would be connected to the line side of the GFCI also.

A GFCI receptacles will trip if they, or any of the wires or devices connected to the load terminals, are shorted.  When a GFCI receptacle is tripped it will disconnect power to the GFCI receptacle and the load terminals.  Power will not be restored until the reset button on the GFCI is pressed.

When updating existing wiring circuits, it may be easier to replace the first receptacle with a GFCI and connect everything else up to the load side.  However, in a kitchen for example, having the refrigerator on the load side of a GFCI, could lead to all of your food spoiling if the GFCI ciruit trips.  In cases like this it might be best just to install GFCIs in the needed locations, and have all wires connected to the Line side of the circuit. 

After the installation is complete always test the circuit with a GFCI circuit tester.  Test both the GFCI receptacle and any downstream or load side receptacles.    

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