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-   -   Different size wires in a circuit (http://www.diychatroom.com/f18/different-size-wires-circuit-19829/)

Randell Tarin 04-12-2008 05:21 PM

Different size wires in a circuit
 
I think I know the answer to this one already, but I seem to remember someone telling me years ago that it is acceptable to feed a smaller gauge conductor from a larger conductor: i.e. #12 feeding a #14, or #8 feeding a #10.

This can't be correct since, for instance a #12 is rated at 20 amps and a #14 is only rated at 15 amps.

However, since it's an accepted practice to use 15 amp receptacles with #12 wire, would it not be acceptable to feed a 15 amp outlet with #14 with that conductor originating in a junction box fed by a #12?

Logic tells me that it's not. But if you don't ask....:yes:

Speedy Petey 04-12-2008 05:33 PM

Why do you need to mix wire sizes in the first place.
Just keep all wires the same size on a circuit.

220/221 04-12-2008 05:34 PM

Quote:

would it not be acceptable to feed a 15 amp outlet with #14 with that conductor originating in a junction box fed by a #12?

Yes......As long as the circuit was protected by a 15 amp breaker.

The breaker protects the wire so it must (generally) be sized according to the smallest conductor.

Randell Tarin 04-12-2008 05:38 PM

Obviously keep them the same size. But, you know as well as I that there are a lot of cheap people in these forums. And there are those who would take shortcuts. The number of DIY horror stories described here will atest to that.

As a hypothetical, could Joe Blow safely run a #14 to a 15 amp plug with the circuit being fed by a junction box from a #12 conductor on a 20 amp breaker?

jrclen 04-12-2008 05:56 PM

Quote:

Originally Posted by Randell Tarin (Post 115790)
As a hypothetical, could Joe Blow safely run a #14 to a 15 amp plug with the circuit being fed by a junction box from a #12 conductor on a 20 amp breaker?

No. That would be neither safe, nor code compliant. The 14 must be protected by no higher than a 15 amp breaker or fuse. Consider, we are talking about duplex receptacles. 2 toasters or 2 hair dryers could be plugged in to that one 15 amp receptacle you mentioned, overloading the 14 gage wire.

Here is something else I have seen. Someone runs #12 wire from the panel to a J-box. Then runs in a couple directions with #14 for receptacle outlets. He properly lands the #12 on a 15 amp breaker. Along comes the next guy, who sees the #12 in the panel and moves it to a 20 amp breaker, not knowing there is #14 in the circuit.

It is best to use the same size wire on the entire circuit unless dealing with a voltage drop on a long run.

Speedy Petey 04-12-2008 06:09 PM

As long as the breaker is sized to the smallest wire on/in the circuit it is safe.

Is it a hack job, yes, but it is safe.

chris75 04-12-2008 06:24 PM

Quote:

Originally Posted by Speedy Petey (Post 115796)
As long as the breaker is sized to the smallest wire on/in the circuit it is safe.

Is it a hack job, yes, but it is safe.

On a DIY forum I agree, in the real world with real electricians, what are you thinking?

Randell Tarin 04-12-2008 07:18 PM

In the real world you sometimes have to make do with what's on hand until you can do it correctly.

There are numerous trades that utilize electricity. When it's a matter of being "McGyver" and jerry-rigging or not getting the job done, people will do whatever's necessary; sometimes to their own detriment.

It's helpful to know what's doable and what's not.

Speedy Petey 04-12-2008 07:40 PM

Quote:

Originally Posted by Randell Tarin (Post 115805)
In the real world you sometimes have to make do with what's on hand until you can do it correctly.

Sure buddy. I live and work in the "real world". It NEVER gets done correctly afterwards. It remains a hack job until either someone replaces the whole mess during a renovation or re-build, or someone gets hurt. :furious:

Someone can try to justify their actions all they want. A hack job is still a hack job.

Silk 04-12-2008 07:57 PM

[quote=Speedy Petey;115811]Sure buddy. I live and work in the "real world". It NEVER gets done correctly afterwards. It remains a hack job until either someone replaces the whole mess during a renovation or re-build, or someone gets hurt. :furious: [quote]

Yeah, I've been there. Didn't have enough stuff to finish the job and had friends who I was "doing a favor for" say they would finish it for me. I trusted them and later got dinged by the inspector for what they didn't finish. It never happened again!

Randell Tarin 04-12-2008 08:23 PM

Quote:

Originally Posted by Joba Fett (Post 115813)
Please don't encourage these frugal DIYer's. It almost seems YOU are looking for a positive response to this type of post, or otherwise why would anyone that has any common s***e post this type of @@@@.
Posts like this are really not necessary.
Please try to do more meaningful things with your time.

No one is encouraging anyone. Just trying to get a good discussion going on a subject that we've all seen done over and over. And besides, I are a frugal DIYer.

I'd rather everyone do it the correct way, but that doesn't always happen does it?

Speedy Petey 04-12-2008 09:20 PM

Quote:

Originally Posted by Randell Tarin (Post 115820)
I'd rather everyone do it the correct way, but that doesn't always happen does it?

No, unfortunately it doesn't. That is why most of us come here to help. We are trying to encourage doing things the right way.

I have to say though, your posts do look like you are looking for justification for NOT doing it the correct way the first time.

Randell Tarin 04-12-2008 11:10 PM

Geez, you guys were chiding me in another thread for using only #12 wire for everything. :huh: I would never, ever do this.

You're wrong. I'm not looking for anyone to condone anything. I had seen this done in practice and had been told it could be done and was just curious to know what the pros thought. I thought other DIYers would benefit from knowing the dangers.

You can think what you want. My intentions were good.

wire_twister 04-13-2008 12:01 AM

what about the ten foot tap rule?

CowboyAndy 04-13-2008 12:20 AM

I have heard alot of people trying to justify doing this with lighting... where you have a 20AMP 12AWG circuit to a bunch of receps, then to a switch. Then they proceed with 14AWG to the lighting.

Again, it's not about what's convient or whatever. Its about code.


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