Tips for How to Wire an Outlet and Three-Way Switch

How to Wire an Outlet

The standard best practice for connecting circuit wires to a switch or receptacle is to use the screw terminals, which are typically located on the sides of the device body.

Another way to wire an outlet is to use the stab-in connectors on the back of the outlet. While generally not recommended, stab-in connections are allowed by code and they speed up the process of wiring an outlet.

1. Strip the Wire

   Strip about 3/4-inch of insulation from each circuit wire using wire strippers. (The ground wire may not be insulated.)

2. Bend the Wire

   Bend the bare end of the wire into a hook, or "U" shape, using needle-nose pliers.
   

3. Attach the Wire to the Screw

   Fit the hook of each wire over the appropriate screw terminal. The wire insulation should be close to (but not under) the screw; only the bare metal of the wire should contact any part of the screw. The hooks should be attached to the screws clockwise so that when the screw is tightened, it will tighten the wire, not loosen it.

4. Stab-In Connection (Optional)

   Many switches and receptacles have holes in the back of the device's body for making stab-in connections. The stripped end of the wire is inserted into the hole, and a spring clip inside the hole holds the wire in place. The stripped copper end of the wire should be exactly the depth of the hole. If the copper end is too long, it may contact another wire and short out the outlet.

5. Close the Wire Loop

   Close the hook snugly around the shank of the screw, using needle-nose pliers.

6. Tighten the Screw

   Tighten the screw clockwise, using a Phillips screwdriver or a square recess screwdriver, whichever fits the screw best. Because the hook is wrapped clockwise around the screw, tightening the screw closes the hook even more. The screw should be very tight, holding the wire firmly below the screw head.

   Warning

   Outlets must be grounded. Connect the circuit's ground wire (bare copper or with green insulation) to the device's ground screw.

How to Wire a GFCI Receptacle

GFCI (ground-fault circuit-interrupter) receptacles are wired much like conventional, non-GFCI outlets with a variation: GFCIs have two sets of terminals, one marked LINE and one marked LOAD.

A GFCI outlet can provide GFCI protection for all downstream devices or just for itself.

• GFCI protection for other devices: If you want the receptacle to provide GFCI protection to the device(s) downstream of the receptacle, use the LINE and LOAD terminals, following the manufacturer's wiring diagram. For example, even regular non-GFCI outlets will be GFCI-protected if they are downstream from a GFCI outlet that is properly wired.
• No additional GFCI protection: If GFCI protection is only needed for the outlet itself and not for other devices, or if the receptacle is at the end of the circuit (end-of-run), use only the LINE terminals, following the manufacturer's wiring diagram. If this receptacle is a middle-of-run receptacle, use short pigtail wires to link the circuit wires to the LINE terminals on the receptacle.

How to Wire a Three-Way Switch

Three-way switches control a light fixture or outlet from two different locations. These switches have two traveler wires and a single common wire.

To wire a three-way switch:

1. Mark COM: Mark the common (or "COM") wire on the old switch before removing the wires. The traveler wires don't need to be labeled because either traveler wire can connect to either traveler screw terminal on the switch.
2. Connect the common wire: Connect the labeled common wire to the COM terminal (usually bronze or dark-colored) on the switch.
3. Connect the traveler wires: Connect the other two wires to one of the light-colored traveler terminals.
4. Connect the ground wire: Connect the bare or green ground wire to the green screw.