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12 outlet gauge wire in house of 14 gauge outlet wires

1875 Views 3 Replies 4 Participants Last post by  seharper
Our house's outlets and switches are all 12 gauge. However, while changing the color of our outlets, we saw that 4 of our outlets had black wires that were too big to backstab into the new outlet (I know now that we need to wind it around the screw, and not backstab), unlike all of the other outlets in the house. Does this mean these 4 black wires are 12 gauge? If so, is there a common reason for this? They're in the dining room. Can we still wind these wires around the gold screws on a 15amp outlet? Or do we need to put wind them on a 20 amp outlet?
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Newer receptacles and switches won't accept the back stab of a 12 gauge wire, whereas older ones would. You're right, use the screws, not the back stabs. You can use 12 gauge wire on a 15 amp receptacle with no problem.
The "15 amp" outlet is a little misunderstood.

If the circuit breaker is 20 amp, then the wiring must be 12 g. End of story on that one.

Where it gets confusing is that people think that they need 20 amp outlets on a 20 amp circuit. The 15 amp is not a rating for how much juice the outlet can handle, it's the plug type. 15 amps is the standard prongs, 20 amps is for heavy duty stuff with the extra "T" prong on the plug. A 20 amp plug will only fit in a 20 amp outlet. If some appliance or tool has a standard plug, then it isn't supposed to draw more than 15 amps, by code. But by code if a kitchen circuit is rated at 20 amps, it's because all the appliances added together can draw more than 15 amps, but no single one of them will.
Generally, outlet amps must match breaker amps. So 50A breaker -> 50A recep. 15A breaker -> 15A recep.

However, they make a special exception to allow the common-as-dirt dual 15A recep on 20A circuits.

That makes sense for two reasons:

- Many circuits (kitchen, bathroom, most commercial circuits) must be 20A.

- UL requires that common 15A receptacles have internal current pathways rated for 20A, i.e. they have 20A pass-through and can support two 10A appliances.
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