Different Size Wires In A Circuit - Electrical - DIY Chatroom Home Improvement Forum


Go Back   DIY Chatroom Home Improvement Forum > Home Improvement > Electrical

CLICK HERE AND JOIN OUR COMMUNITY TODAY...IT'S FREE!

Reply
 
Thread Tools Display Modes
Old 04-12-2008, 05:21 PM   #1
Member
 
Join Date: Jan 2008
Posts: 309
Rewards Points: 250
Default

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....

Advertisement


Last edited by Randell Tarin; 04-12-2008 at 11:17 PM.
Randell Tarin is offline   Reply With Quote
Old 04-12-2008, 05:33 PM   #2
Licensed Electrical Cont.
 
Speedy Petey's Avatar
 
Join Date: Feb 2004
Location: NY State
Posts: 6,904
Rewards Points: 2,162
Default

Different size wires in a circuit


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

Advertisement

__________________
Sometimes I feel like if I answer any more questions it is like someone trying to climb over a fence to jump off a bridge and me giving them a boost.
Answers based on the 2008 & 2011 NEC.
Speedy Petey is online now   Reply With Quote
Old 04-12-2008, 05:34 PM   #3
Member
 
Join Date: Oct 2007
Posts: 2,294
Rewards Points: 1,000
Default

Different size wires in a circuit


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.
220/221 is offline   Reply With Quote
Old 04-12-2008, 05:38 PM   #4
Member
 
Join Date: Jan 2008
Posts: 309
Rewards Points: 250
Default

Different size wires in a circuit


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?
Randell Tarin is offline   Reply With Quote
Old 04-12-2008, 05:56 PM   #5
Licensed Electrician
 
jrclen's Avatar
 
Join Date: Feb 2008
Location: central wisconsin
Posts: 982
Rewards Points: 500
Default

Different size wires in a circuit


Quote:
Originally Posted by Randell Tarin View Post
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.

Last edited by jrclen; 04-14-2008 at 01:14 PM. Reason: fingers go faster than brain sometimes
jrclen is offline   Reply With Quote
Old 04-12-2008, 06:09 PM   #6
Licensed Electrical Cont.
 
Speedy Petey's Avatar
 
Join Date: Feb 2004
Location: NY State
Posts: 6,904
Rewards Points: 2,162
Default

Different size wires in a circuit


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.
__________________
Sometimes I feel like if I answer any more questions it is like someone trying to climb over a fence to jump off a bridge and me giving them a boost.
Answers based on the 2008 & 2011 NEC.
Speedy Petey is online now   Reply With Quote
Old 04-12-2008, 06:24 PM   #7
Electrician
 
Join Date: Aug 2007
Location: Connecticut, Litchfield
Posts: 2,015
Rewards Points: 1,000
Default

Different size wires in a circuit


Quote:
Originally Posted by Speedy Petey View Post
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?
chris75 is offline   Reply With Quote
Old 04-12-2008, 07:18 PM   #8
Member
 
Join Date: Jan 2008
Posts: 309
Rewards Points: 250
Default

Different size wires in a circuit


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.
Randell Tarin is offline   Reply With Quote
Old 04-12-2008, 07:40 PM   #9
Licensed Electrical Cont.
 
Speedy Petey's Avatar
 
Join Date: Feb 2004
Location: NY State
Posts: 6,904
Rewards Points: 2,162
Default

Different size wires in a circuit


Quote:
Originally Posted by Randell Tarin View Post
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.

Someone can try to justify their actions all they want. A hack job is still a hack job.
__________________
Sometimes I feel like if I answer any more questions it is like someone trying to climb over a fence to jump off a bridge and me giving them a boost.
Answers based on the 2008 & 2011 NEC.
Speedy Petey is online now   Reply With Quote
Old 04-12-2008, 07:57 PM   #10
electrician
 
Join Date: Feb 2008
Posts: 326
Rewards Points: 250
Default

Different size wires in a circuit


[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. [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!
Silk is offline   Reply With Quote
Old 04-12-2008, 08:23 PM   #11
Member
 
Join Date: Jan 2008
Posts: 309
Rewards Points: 250
Default

Different size wires in a circuit


Quote:
Originally Posted by Joba Fett View Post
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?
Randell Tarin is offline   Reply With Quote
Old 04-12-2008, 09:20 PM   #12
Licensed Electrical Cont.
 
Speedy Petey's Avatar
 
Join Date: Feb 2004
Location: NY State
Posts: 6,904
Rewards Points: 2,162
Default

Different size wires in a circuit


Quote:
Originally Posted by Randell Tarin View Post
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.
__________________
Sometimes I feel like if I answer any more questions it is like someone trying to climb over a fence to jump off a bridge and me giving them a boost.
Answers based on the 2008 & 2011 NEC.
Speedy Petey is online now   Reply With Quote
Old 04-12-2008, 11:10 PM   #13
Member
 
Join Date: Jan 2008
Posts: 309
Rewards Points: 250
Default

Different size wires in a circuit


Geez, you guys were chiding me in another thread for using only #12 wire for everything. 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.
Randell Tarin is offline   Reply With Quote
Old 04-13-2008, 12:01 AM   #14
electrical contractor
 
Join Date: Feb 2008
Location: Georgia USA
Posts: 181
Rewards Points: 150
Default

Different size wires in a circuit


what about the ten foot tap rule?
__________________
Jimmy

Life is tough, Life is tougher when you are stupid.
wire_twister is offline   Reply With Quote
Old 04-13-2008, 12:20 AM   #15
When is fishing season?
 
CowboyAndy's Avatar
 
Join Date: Feb 2008
Posts: 613
Rewards Points: 500
Default

Different size wires in a circuit


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.

Advertisement

__________________
I DON'T OWN MY HOUSE...
MY HOUSE OWNS ME!
CowboyAndy is offline   Reply With Quote
Reply


Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Need a wiring diagram Mooreski Electrical 46 03-12-2011 04:25 PM
Circuit breakers and wire size stan 41943 Electrical 19 03-06-2008 03:29 PM
Transformer Help chcustom Electrical 28 12-10-2007 11:40 PM
So lost - electrical requirements please help lapsis9 HVAC 4 12-20-2006 09:09 PM
Number of receptacles and size of wires KUIPORNG Electrical 5 06-28-2006 02:21 PM




Top of Page | View New Posts