12 gauge and 14 gauge wire on the same 15A circuit

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  #1  
Old 03-22-06, 07:32 AM
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12 gauge and 14 gauge wire on the same 15A circuit

I have found some 15A circuits in my house that the previous owner had made some additions to at some point using 12 gauge wire on an existing 14 gauge 15A circuit. The 14 gauge wire leaves the main panel and goes out to some outlets and lights (nothing major), but there is some 12 gauge wiring added to the circuit for a few additional receptacles. The total circuit is still within means of a normal circuit (No major loads, 8-10 receptacles, small lights), but is it bad to mix 12 gauge and 14 gauge wire on a 15 A circuit when the circuit starts with 14 gauge, or does it not matter? Since 14 gauge leaves the main panel, there will never be mistakinly a 20A breaker put on it and it would be very hard to replace the 12 gauge wiring on the circuit.
 
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Old 03-22-06, 07:49 AM
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Originally Posted by wizzard5150
The total circuit is still within means of a normal circuit (No major loads, 8-10 receptacles, small lights)
This part of your statement makes no sense. In a residential setting there is no limit for general purpose circuits.



As for your issue. This is not a code violation. The previous owner was ignorant and/or cheap and/or lazy. Either he didn't know what he needed so he bought 12 gage, he had some 12 gage wire leftover, or he only wanted to buy one size.

The main reason we advise against mixing wire sizes on a circuit is to prevent someone from incorrectly upsizing a 15 amp breaker to 20 amps, because they see 12 gage wire and think the entire circuit is 12 gage. This is less likely to happen if the wire at the main panel is 15 gage, but it could still happen.

My recommendation is for you to make a note on the breaker panel that "Circuit X is a combination of 14 and 12 gage wire Maximum breaker size is 15 amps," or something similar.
 
  #3  
Old 03-22-06, 11:35 AM
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Originally Posted by racraft
This part of your statement makes no sense. In a residential setting there is no limit for general purpose circuits.
My original statement that you are questioning above was just more of a rule that I've always understood to be widely used as a guideline when planning circuit...that is that you should never put more than 12 (but I always shoot for 8-10) total receptacles and/or light fixtures on a single 15A or 20A circuit. If this is not the case, then I am misinformed. I'd rather error on the side of caution though.

I guess what I am looking for in my original post is if there is any sort of risk (fire/shock/overloading) in leaving a mixed 12&14 gauge wire circuit, provided the breaker always remains 15A? If not, I'll just take your advise and mark the breaker in the panel that it is a mixed circuit and leave it at that.

Thanks again.
 
  #4  
Old 03-22-06, 11:47 AM
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Assuming that all connections are correct, there is no fire or shock danger with having wire that is larger (smaller gage) than required by code.

It is certainly a good idea to limit the number of receptacles on a circuit, especially if you don;t know exactly what they will be used for. As for lights, you need to plan lighting circuits based on the maximum wattage for each light and 80 percent of the circuit capacity.
 
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