Quote: I failed an inspection once because of mixed wire, I won't do that again.
I think I would have argued that one but I'll have to see how the code reads. On a long circuit run you should up size the wire and you can't easily terminate number 8 or 10 to a bunch of receptacles. From a technical standpoint the heavy wire should always be at the breaker but the code might read differently.
Because a long run might require a larger than expected wire size, no electrician (or homeowner) should think about changing out a breaker just because they find an oversized wire at the breaker panel.
That said, I would not combine wire sizes since it is bound to lead to confusion if the need to troubleshoot the run comes up in the future. Although it appears that code might allow mixed wire sizes if the breaker protects the smallest wire, there are many inspectors that will red tag a job if he/she finds it. Since the process of appealing an inspector's decision is a pain, I'd go for one size for the entire run.
Original poster here. Thanks for all the input. There are no codes/inspections where I live. Having said that, I want to do the right thing but try and not be wasteful also.
The point was made about the length of the run. As a matter of fact, if I had just a few more feet in this project it would call for #10 on the 20 amp breaker. For someone to assume that just because there is a #10 wire at the main panel on a 20 amp breaker that it can be switched to a 30 amp breaker is not too smart; I'm no electrician but I know that much.
I called an electrical supply company and I spoke with their on-site guy who is not a licensed electrician but makes all of there recommendations. He said a professional electrician wouldn't mix sizes if it were a paying customer he would probably go for it on a home project of his own. He suggested that I use the larger wire first to maintain the voltage in the longest part of the run and then use the #12 for short "branches" and try and end up with #12 at the connection points as it was much easier to work with.
Any additional thoughts or comments? I always respect and appreciate the opinions I get form this forum.
although you my not have any inspection authority in your area everyone is bound to meet the minimums of the NEC. that said there is nothing to prohibit you from using 2 size wires as long as they are properly protected. I wouldn't myself as splices can always become a trouble spot in the future. the run is only 50 feet go to the supply house and buy a single piece of that length, I would use #10 on a 30a breaker for your rv.
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I would have done the job first, and then come here and tell'm what works !
Even a genuine elect tech will run a string of plugs on 12 ga, then run 14 ga to the last plug. Thats not mixing wire ? Give the OP a break, help him save some money ! Thats why he came here.
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The NEC permits you to use any size wire from #14 copper or #12 alum. up, as long as it is fused base on the smaller size in the circuit. You could use a dozen difference size wires as long as it is protected to the smallest size.
I have used #8 copper many times due to distance for circuits from a house to garage or out building, but fused it at 20 amps. because the garage or out building was wired with #12 copper.
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RJsfishin wrote: I would have done the job first, and then come here and tell'm what works !
Even a genuine elect tech will run a string of plugs on 12 ga, then run 14 ga to the last plug. Thats not mixing wire ? Give the OP a break, help him save some money ! Thats why he came here.
What makes you think the last outlet is line is diffrent load than the first? Any inspector finding that will gig the installer. Poor practice to say the least.
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RJsfishin wrote: I would have done the job first, and then come here and tell'm what works !
Even a genuine elect tech will run a string of plugs on 12 ga, then run 14 ga to the last plug. Thats not mixing wire ? Give the OP a break, help him save some money ! Thats why he came here.
What makes you think the last outlet is line is diffrent load than the first? Any inspector finding that will gig the installer. Poor practice to say the least.
Well, I guess you're, like me, not an electrician.
But even I know that the run to the last plug on a string is only carrying the load of one plug, whereas all the rest of them must carry the full load of any plugs after them, and therefore 14 ga wire to the last plug is perfectly normal, and to code, and I know of hundreds of houses to be wired that way. If some code of yours differs, I'm sorry, but that doesn't change anything.
I would have done the job first, and then come here and tell'm what works !
Even a genuine elect tech will run a string of plugs on 12 ga, then run 14 ga to the last plug. Thats not mixing wire ? Give the OP a break, help him save some money ! Thats why he came here.
Jamesrpm wrote:
What makes you think the last outlet is line is diffrent load than the first? Any inspector finding that will gig the installer. Poor practice to say the least.
RJsfishin wrote:
Well, I guess you're, like me, not an electrician.
But even I know that the run to the last plug on a string is only carrying the load of one plug, whereas all the rest of them must carry the full load of any plugs after them, and therefore 14 ga wire to the last plug is perfectly normal, and to code, and I know of hundreds of houses to be wired that way. If some code of yours differs, I'm sorry, but that doesn't change anything.
The only way this would pass is if it was protected by a 15 amp breaker. There are places where #14 could be run on a 20 amp breaker (for example as fixture wire in a short run of flex or conduit to go between a junction box & a lighting fixture or as a tap) but running the last part of a run of receptacles with undersized wire won't cut it; it must meet the code for a branch circuit (240.4D). It does not meet the requirements as a tap.
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