Adding 14awg wire to 20A circuit

Mar 26, 2007 15 Replies

I added a light fixture to an existing 20A 12awg circuit, and didn't realize I used 14awg romex until I was done. The new fixture wouldn't overload even a 15A circuit, so a) are you gonna tell me I have to fix my error and put in the larger cable, and b) why is that? Thanks


"Em" was just pondering this little gem:

YES!

So you can sleep at night?

Your welcome. ;-)

It may be a lot easier to put a 15 a breaker on that circuit. If 15 will carry the other things on that circuit, then you are done.

So, when one of the wirenuts starts getting loose and causes an 19A circuit, you feel safe knowing that the 20A breaker won't trip, but the 14awg wiring isn't rating for 19A?

While replacing the cable would be good, it might be better to just swap out the breaker.

I don't believe there is anything in the code to prevent you from changing the breaker to protect the smallest conductor, but IMO, despite labels and tags, it would seem to me all to easy for someone down the line to inadvertently put a 12 gauge conductor back on a 20 amp breaker, not knowing what you've done. I would change the cable to the light.

That is a good catch and I agree. The better way is to change out the cable. If it is not specifically in the code, it certainly is in the spirit of the code.

What if he turns off the light at night? Could he sleep then?

I would replace the cable. Either that or stuck a small fuse (1-2A quick blow) on the part where the #14 taps into the 20A circuit.

At least in theory which is why there is a safety factor built into the code.

We went over this some months back, and I don't believe anyone could come up with a code violation, which seems strange to me, but I know I couldn't find one

somone 30 years from now could plug a power saw into a screw in adapter and pull the full load 20 amps plus the breakers over currtent amount.

24 amps on 14 gauge NOT GOOD AT ALL!

Yiour use may not be the next owners use:(

Not if it's on a 15 amp breaker, which was the OP's solution

Nope because they don't make a screw in adapter that takes a 5-20 plug.

Em, Is the 14awg cable switched, or not switched? If it's switched, I would leave it alone (even though it is a technical code violation) because nobody is gonna come along later and extend the circuit and install a half dozen receptacles. If it is not switched, you have to be concerned with what some idiot is going to add on to it 20 years from now.

Noozer,

14 gauge copper wire *is* rated for 20A, the code just says you have to derate it to 15A anyway. Your 19A scenario wouldn't hurt anything.

Bob

Agreed.

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