Electrical Basics ~ Residential Wiring Diagrams

Wiring Diagrams ~ The GFCI : Ground Fault Circuit Interrupter...

The GFCI outlet is designed, to be wired in a "Line/Load" configuration. Where the "Line" is the source, feeding the GFCI. This is called the line side of the outlet.

The "Load" or "load side" of the GFCI, will feed any outlets to be protected. This allows for multiple, downstream, outlets to be fed by 1 GFCI.

The Line and Load sides of the GFCI will be clearly marked. Wire accordingly. Wire the downstream receptacles as normal.

See: How Does A GFCI Work? >

In the diagram below, you have a GFCI that feeds 3 outlets. However, only 2 of them are fed from the "load" side of the GFCI. They are protected. The other outlet, is pigtailed from the line side of the GFCI. This leaves the outlet unprotected.

Note: To wire a single GFCI, simply connect the source conductors to the "Line Side" of the receptacle.

Wiring Diagrams ~ The 3-Wire Home Run

When a cable leaves your electrical panel, it's called a "home run". Meaning that it is the source, for a branch circuit. It would be ran to a "home run" box...the starting point of the circuit. From here, it branches out to feed other devices on the circuit.

Most homes, will have both 2-wire and 3-wire home runs feeding the branch circuits.

The 2-wire "HR" is simple enough, one circuit...power in and power out. The 3-wire "HR" is just as simple. The difference is that it carries two circuits from the panel, in one cable. These two circuits will share a common neutral/grounded conductor. This is cost effective, as it saves both time and material.

In this example, the 3-wire HR is feeding circuits A and B. From the home run box, circuit A feeds a light switch and an outlet. And circuit B, heads off to feed another area of the home.

!! CAUTION: If you find yourself troubleshooting a 3-wire HR...Do not disconnect the neutrals in a "hot/live" home run box. The resulting lost neutral could cause severe property damage. Be safe and turn the circuit off !!

Note: Newer homes may feature a 4-wire HR, particularly in the case of AFCI protected circuits. This system provides each of the two circuits, their own neutrals, rather than the shared neutral used in a 3-wire system.