DIY Wiring Diagrams for Electrical Receptacles
Also see:This page contains wiring diagrams for most household receptacles including grounded and ungrounded duplex receptacles, ground fault circuit interrupters (GFCI) as well as 20 and 30 amp 240 volt receptacles.
Grounded Duplex Receptacle
The standard duplex wall receptacle wiring diagram. This is a polarized outlet. The long slot on the left is the neutral contact and the short slot is the hot contact. A grounded contact at the bottom center is crescent shaped. Always connect the hot and neutral wires properly and don't use this receptacle when no ground wire is available.
Ungrounded, Polarized Duplex Receptacle
This is an older version of the above receptacle. It lacks a grounding contact, the receptacle slots are different sizes. This receptacle does not make use of a ground wire. There is no protection against electrocution as provide by the grounded receptacle. When replacing a ungrounded, polarized receptacle use this type and not the grounded receptacle above unless it is grounded to a metal outlet box that is tied to the house ground.
Ungrounded Duplex Receptacle
This is the oldest version of the above receptacles. It lacks a grounding contact and the receptacle slots are the same size. These receptacles did not make use of a ground wire and both hot and neutral wires were treated the same. With this configuration any wire may be hot at all times. There is no protection against electrocution as provide by the grounded receptacle. When replacing a ungrounded receptacle in an older circuit use the polarized one above and not the grounded receptacle at the top unless it is grounded to a metal outlet box.
Wiring GFCI Receptacles
There are two sets of terminals on a ground fault circuit interrupter receptacle: the line terminals and the load terminals. The source from the circuit should be connected to the line terminals. Any standard duplex receptacles connected to the load terminals will be protected by this GFCI receptacle.
To wire more than one GFCI receptacle in the same circuit, connect the source to the line terminals on each fixture using a pigtail splice. The load terminals are not used for this circuit.
20-Amp 120-Volt Duplex Receptacle
A 20 amp, 120v duplex receptacle should only be install in a circuit using 12 awg or larger cable and a 20 amp circuit breaker. Use this receptacle for heavy appliances like refrigerators, washing machines and microwaves.
20-Amp 240-Volt Appliance Receptacle
This outlet is commonly used for a heavy load device such as an air conditioner. The outlet should be wired to a dedicated 20-amp breaker in the service panel using 12|2 awg cable for a 240 volt receptacle. With this wiring both the black and white wires are used to carry 120 volts each. Wrap black electrical tape to the ends of the white wire to label it hot. This circuit doesn't make use of a neutral wire. The plug slots are configured to accept only plugs from compatable appliances.
30-Amp 240-Volt Receptacle
This type of receptacle is used for electric ranges and dryers requiring 240 volts. The smallest cable for a 30-amp circuit is 10 awg. A 3-conductor cable is needed to carry 240 volts.
