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Old 11-05-2007, 11:12 AM   #1
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Load Capacity

Hi Everyone,

I'm a newbie to the forum so I apologize if these are dumb questions.

First - in a residential environment, can you mix 14 and 12 guage wire? Basically, if it's a 14 guage circuit, can I use 12 guage wire to add another outlet, light or switch, or does that create problems? Or vice versa, adding 14 guage wire to a 12 guage circuit. This is all 15 amp service.

Second question. How can I determine the max load for a new 15 amp circuit? I'm finishing the basement. Most rooms are simple, but in one room I have 3 recessed lights, plus 6 wall sconce lights, plus 2 ceiling fans (w/o light kits). I'll have receptacles all arounds, probably 7 total, but none will have anything plugged into it. Should I split this room into two or more circuits?




Last edited by Woodcutter; 11-05-2007 at 11:41 AM.
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Old 11-05-2007, 12:51 PM   #2
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First: It is not considered good workmanship to mix wire gauges, but there is no restriction in doing so as long as the overcurrent protection (breaker) is sized for the smallest wire gauge used. So if you have 14ga wire in the circuit, you MUST use a 15A breaker.

Second: Maximum load on a 15A circuit is 15A. There is no restriction on the number of outlets on a 15A general use circuit in a dwelling, but an often used "guideline" is 12. You can put everything in your basement on the same circuit, but it is better to run separate circuits for lights and receptacles if at all possible.

If any of these planned receptacles are for a bathroom, there are additional restrictions that apply (20A, 12ga wire, dedicated circuit).


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Old 11-05-2007, 01:32 PM   #3
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Thanks HouseHelper. On the first item, I raised the question because of an oversight I made. I added a switch to an existing pull string light using 14 guage wire, then noticed after I had it all done that the existing wire is 12 guage. It is a 15A circuit, so it looks like I do not need to do a do over.

With respect to the second question, from what you are saying, it does not sound like I need to breakup the lighting in this room onto multiple circuits. That will make it much easier if I can keep them on the same line. I plan to put all the outlets in the basement on a single, seperate 15A line, except for the shop, which I the township said I needed to put on a 20A ground fault line, seperate from the lights. I plan to use a 20A GFCI breaker to do that. I'll use 12/2 for that line.

Thanks again. I appreciate your help.
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