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Wiring Diagrams for Receptacles and Switches


wiring diagram for a duplex receptacle

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.


wiring diagram for a non-grounded duplex receptacle

Ungrounded Duplex Receptacle

This is the old version of the above receptacle. It lacks a grounding contact and the receptacle slots are the same size. Older 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 this type and not the grounded receptacle above unless it is grounded to a metal outlet box.


wiring diagram for a GFCI, ground fault circuit interrupter

GFCI Receptacle

The electric code requires that a ground fault circuit interrupter (GFCI) receptacle be installed within 6 feet of a water fixture. This outlet has a built-in circuit breaker. When a short is detected the electrical flow is stopped instantaneously to protect against deadly electrocution. It is recommended that a gfci be tested monthly to ensure it is working.


wiring diagram for a 20 amp 120 volt receptacle

20-Amp Single 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 120 volt and 12|3 for 240 volt receptacle.

wiring diagram for a 20 amp 240 volt receptacle

wiring diagram for a 30 amp receptacle

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.

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