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During an effort to add an additional circuit my garage, I discovered that my house, which was built in 1999, has 14 AWG wire run off 20a breakers. My questions are simple:

Was this valid under code at the time of construction?

Do I have a problem that needs to be corrected?

I'm caught between trusting the circuits as they are, or biting the bullet and swapping all my breakers (about 20) for 15a. Not an insignificant cost or effort.

My background: I am a structures engineer. Basic electrical theory was covered as part of my education. I've been playing with electronics since I was a wee bairn. I recognized that this was insufficient to be play with electricity in the real world so I pulled up the 2016 NEC and drilled into relevant sections. After my fun quota was filled by that, I settled down with Wiring Simplified (44th ed.) to make it all make sense. With all that, I'm pretty confident that I understand residential wiring at a better-than-apprentice level.

  • Directly swapping 20 20-amp breakers for 15-amp breakers in place shouldn't take more than an hour or two. As far as cost, if you're just replacing breakers to meet code standards of the day, most non-AFCI/GFCI 15-amp breakers sit in the $5 range which makes it about $100. If you're upgrading to AFCI breakers to meet modern code, then I agree you are looking at more significant costs. – statueuphemism Sep 9 '16 at 19:06
  • Don't assume it's 14AWG on every circuit; look. Also don't assume white Romex means 14AWG, that was only recently adopted by a few manufacturers and is a manufacturer convention not a standard. – Harper Sep 10 '16 at 16:07
  • I want to thank you all for your responses. I believe I've got the matter sorted and unfortunately, the answer is not a good one. I open my breaker panel to inspect the wiring. In my house, I have non-color coded NM. I inspected all the wires leaving the breakers. At all the 20a breakers, I have 12 AWG wire originating and departing the panel to their end points in the house. What is bad is that I found that at least in my garage circuit, they mixed 12 & 14 AWG wire. I went ahead and derated that circuit to 15a. – Stevie T Sep 12 '16 at 13:20
  • As soon as the heat breaks, I'll get into my attic space and inspect the wiring and see if I have any addition buggered circuits. The exact count is 12 breakers affected so fixing the problem will be under $50 and an hour's time. I also see to the right that there is a question regarding 14 ga branch on a 12 ga circuit. I'm going to go spend time in that thread. Thank you all. – Stevie T Sep 12 '16 at 13:21
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The answer is no this was not code in 1999. 14 Awg has been limited to 15 Amp breakers at least since the 70's. If there is a fire some insurance companies will not pay if the service has been modified without permit. Since the wire size is wrong for the breakers this could be a way out for them if a problem did occur. Breakers can be found on line for a few dollars each make sure to match the type with the panel and the brand for the safest fix.

  • I think I was adding that when you were adding the comment, thanks. – Ed Beal Sep 9 '16 at 13:48
  • The whole "the insurance company will not pay..." mantra is for the most part not true in cases like this. – Speedy Petey Sep 9 '16 at 18:25

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