Forums | Home Repair | Home Improvement | Painting | Interior Decorating | Remodeling | Landscaping


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

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

Reply
 
Thread Tools Search this Thread Display Modes
Old 01-10-2012, 05:52 PM   #1
Member
 
Join Date: Jan 2012
Posts: 84
Share |
Question

Romex 12/3 or 12/4


If you are running a length of Romex 12/3 the black and red of which are the Hs from two different CBs, can you use the same white wire for the N for both circuits?

Basically can you use 12/3 for two CBs using the same white wire for the N for both circuits?
highdeserthome is offline   Reply With Quote
Old 01-10-2012, 05:53 PM   #2
Electrical Contractor
 
jbfan's Avatar
 
Join Date: Jun 2004
Location: Newnan GA
Posts: 5,472
Default

Romex 12/3 or 12/4


Quote:
Originally Posted by highdeserthome View Post
If you are running a length of Romex 12/3 the black and red of which are the Hs from two different CBs, can you use the same white wire for the N for both circuits?

Basically can you use 12/3 for two CBs using the same white wire for the N for both circuits?
Yes. This is known as a multiwire branch circuit.
__________________
Yes I am a Pirate, 200 years too late. "Jimmy Buffett"
jbfan is online now   Reply With Quote
Old 01-10-2012, 05:59 PM   #3
Love for Construction
 
<*(((><'s Avatar
 
Join Date: Mar 2009
Location: Idaho
Posts: 317
Default

Romex 12/3 or 12/4


Quote:
Originally Posted by highdeserthome View Post
If you are running a length of Romex 12/3 the black and red of which are the Hs from two different CBs, can you use the same white wire for the N for both circuits?

Basically can you use 12/3 for two CBs using the same white wire for the N for both circuits?
Yes, its called a Multi-wire Branch Circuit (MWBC). It has been covered on this site quite a bit.

1. The two circuits have to be on opposite phases of each other so the power on the neutral will not be cumulative.
2. The circuit breakers (depending on location, but always recommended) need to have a handle tie, so that one cannot be shut off independently from the other circuit.
3. The neutral wires at the receptacles must be pig-tailed before attaching to the receptacle.
__________________
-luke-

Last edited by <*(((><; 01-10-2012 at 06:02 PM.
<*(((>< is offline   Reply With Quote
Old 01-10-2012, 06:07 PM   #4
Member
 
Join Date: Jan 2012
Posts: 84
Question

Romex 12/3 or 12/4


Quote:
Originally Posted by <*(((>< View Post
Yes, its called a Multi-wire Branch Circuit (MWBC). It has been covered on this site quite a bit.

1. The two circuits have to be on opposite phases of each other so the power on the neutral will not be cumulative.
2. The circuit breakers (depending on location, but always recommended) need to have a handle tie, so that one cannot be shut off independently from the other circuit.
3. The neutral wires at the receptacles must be pig-tailed before attaching to the receptacle.

If I put the two leads of my multimeter on the hots, if it reads 240 then they are opposite phases? Usually for CB immediate next to each other or odd and even location will be opposite phase? Is this true even for the Pushmatic Bulldog?
highdeserthome is offline   Reply With Quote
Old 01-10-2012, 06:10 PM   #5
Member
 
Join Date: Jan 2012
Posts: 84
Default

Romex 12/3 or 12/4


"The two circuits have to be on opposite phases of each other so the power on the neutral will not be cumulative."

Thanks This info really answered my question. I wondered about the load on the N for this setup.
highdeserthome is offline   Reply With Quote
Old 01-10-2012, 06:11 PM   #6
MarginallyQualified
 
Join Date: Dec 2011
Location: Winston-Salem NC
Posts: 3,460
Default

Romex 12/3 or 12/4


Quote:
Originally Posted by highdeserthome View Post
Basically can you use 12/3 for two CBs using the same white wire for the N for both circuits?
If the wire isn't already installed... try to avoid putting a MWBC in.
If it is installed... be careful of how the rest is done.
TarheelTerp is offline   Reply With Quote
Old 01-10-2012, 08:04 PM   #7
Electrical Contractor
 
kbsparky's Avatar
 
Join Date: Sep 2008
Location: Delmarva
Posts: 3,352
Default

Romex 12/3 or 12/4


Quote:
Originally Posted by highdeserthome View Post
If I put the two leads of my multimeter on the hots, if it reads 240 then they are opposite phases? Usually for CB immediate next to each other or odd and even location will be opposite phase? Is this true even for the Pushmatic Bulldog?
Bulldog breakers are a different animal. Be sure to use a double-pole breaker, where both sides are connected with a top piece.

And yes, when you have properly connected it up, you will measure 240 Volts between the black and red conductors.
__________________
-KB

Life is uncertain -- eat dessert first!!
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
kbsparky is offline   Reply With Quote
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search
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
Identify age of old Romex - also funny ground Leah Frances Electrical 9 02-06-2012 12:07 AM
How to build a romex spinner jimmy21 Electrical 17 02-06-2012 12:01 AM
Fishing Romex through walls Tetranitrate Electrical 6 07-09-2011 06:12 AM
romex clamped against bx knockout in old box kbm774 Electrical 11 08-16-2010 01:53 PM
12/3 Romex to Feed 2 Circuits? DaveHembree Electrical 22 09-28-2007 08:24 AM




Top of Page | View New Posts

Copyright © 2003-2014 Escalate Media. All Rights Reserved.