Okay, so here is what I got. I have done a fair amount of replacing switches and outlets but this is my first time adding outlets.

I have a 15 amp breaker in the box running a couple of lights and outlets in my basement. I want to move one outlet and add 3 more to the series. The outlet at the end of the stream is a 20 amp outlet, and it looks like it has 12/2 wire attached to it.

I want to know if I can add 14/2 wire to finish adding the outlets, or if I need to continue the 12/2.

  • Can you trace that wire to the previous box? – ThreePhaseEel Feb 18 '19 at 17:18
  • I can't it is all boxed in. It powers 6 overhead lights in addition to the outlet so I am rethinking the whole thing now any way. My box is full so I can't even add a run. – Kevin Weaver Feb 19 '19 at 18:12
  • FYI, it's common (and acceptable) to use 15A outlets and switches on a #12/20A circuit in a residential situation. – isherwood Feb 20 '19 at 21:59

You can extend the circuit but it is bad practice to put #14 awg wire on a circuit that originates with #12 awg wire. For example; the reason is because someone tosses a mini fridge on the circuit and now the breaker trips, going back to the panel you many years later or the next owner sees #12 wire and installs a 20 amp breaker not knowing or remembering there was 14 in the run. This can result in a fire especially with back stabs in use and the smaller wire size. I have actually found this exact change of events on several occasions over the years. 12 awg is not that much more than 14 awg so it is best to continue with 12 awg , if you go cheap make sure to label the wiring in the service panel as connected to #14 , but even that is a bad practice compared to running #12.

  • Thank you. I had purchased the 14/2 knowing it was a 15 amp breaker, I was surprised to find the 12/2 in the wall. Thanks for the info. – Kevin Weaver Feb 19 '19 at 18:13

I am not an electrician, but I think this is the "book answer": A quick googling tells me that 14-gauge wire is rated for 15amps. So since you have a 15-amp breaker controlling this circuit, you should be safe to use 14-gauge wire.

However, if this were my own project, I would not be happy with the book anwswer, I would want even more safety-factor. I would continue the 20-amp rated line and outlets, and keep the 15-amp breaker controlling it all. This has the effect that the outlets and the lines in your walls will stay nice and cool; the 'bottleneck' of the circuit is the 15-amp breaker itself which is exactly what you want.


I would investigate further. Map the whole circuit. If it's all #12 wire, then I would stay with #12 wire, and then you would be able to upgrade the breaker to 20A. If there is any #14 wire, it must be 15A.

It's entirely possible the guy wired the circuit (or the whole house) with #12 - that's what I would do - and then some home inspector told him he needed 15A circuits in bedrooms or similar nonsense. That's not true, you can wire all #12/20A if you really want to.

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