Wiring needed for 20A residential receptacles.

Old 02-23-15, 02:45 PM
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Post Wiring needed for 20A residential receptacles.

I was planning to use 12-AWG gauge non-metallic indoor wire with 3 conductors to rewire some of the 15 amp plugs in my house.

A friend told me this would be best wire to use. But when should a 14-AWG gauge wire be used instead and when should wire with only 2 conductors be used?
Old 02-23-15, 02:56 PM
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Well actually you would use 2-conductor (+ gnd) not 3- conductor. Why are you using a 20 amp breaker? Is it a kitchen or bath or... Oh, and you are not installing plugs. You are installing receptacles. Plugs are male connectors that go into the female receptacle.
Old 02-23-15, 03:24 PM
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If any portion of the circuit has (or still has) 14 gauge wire then the maximum breaker rating is 15 amps. Many homes nowadays have 12 gauge 20 amp circuits even for a string (daisy chain) of ordinary receptacles and also switch controlled light fixtures in a living room or a bedroom.

Some locations such as the laundry area need a 12 gauge 20 amp circuit for that area exclusively to meet the most up to date code.

There are some uses for 3 conductor cable as a combination 120/240 volt circuit, also called a multiwire branch circuit. The beginning home handyman may want to avoid this kind of circuit until he gains more wiring experience.

Last edited by AllanJ; 02-23-15 at 03:39 PM.
Old 02-24-15, 07:44 AM
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You can have 15 amp receptacles on a 20 amp circuit as long as there are at least two of them. You cannot have a 20 amp circuit with any 14 ga wire or cable anywhere in it.

12-2 and 14-2 (two wire) are standard cables, 12-3 and 14-3 (three wire) are less commonly used with things like three-way switches and ceiling fan/light combination fixtures and switches.

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