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 04-01-2013, 04:05 PM   #1
Member
 
ericmunyon12345's Avatar
 
Join Date: Feb 2013
Posts: 55
Share |
Question

Shared neutral Question.


I have two circuits running to four switches to control some 120v plug-in fans in a shop. Can I (1) use 12-3 wire between the two, 2-gang boxes just to reduce the cluster in the boxes? (I know, why not do that from the panel to have a mwbc? I didn't run the original feeds; I'm adding the switches).
If I do use 12-3, effectively giving the circuits a shared neutral in the middle of the run, is a double-pole breaker required?
I'd like to think there is no problem with this as the neutrals are connected at the bus bar anyway, but I so appreciate the advice from the licensed pros who check in on this board. Thanks!

ericmunyon12345 is offline   Reply With Quote
Old 04-01-2013, 04:58 PM   #2
Semi-Pro Electro-Geek
 
Join Date: Jul 2009
Location: Arizona, USA
Posts: 2,531
Default

Shared neutral Question.


I can't tell exactly what you're describing, but it doesn't sound code compliant. It sounds like you have two separate circuits feeding two separate boxes, and you've made some kind of an interconnection between them, and that interconnection carries neutral current both ways depending on the circumstance. That's a problem on a couple levels. First, you probably have net current flow through that interconnect cable. In other words, not all current carrying conductors are in the same cable. This is a no-no. Second, if you are passing current between two independent circuits you are violating one of two rules depending on how you're doing it. Either you created a MWBC and need handle ties or a 2P breaker, or you have a situation where the power from one breaker may energize the load terminals of another breaker. Either way it's a problem. Exactly how do you have this connected? Can you post a diagram?

__________________
I am a lawyer, but not your lawyer. And who cares anyways? We're here to talk construction. This is DIY advice, not legal advice.
mpoulton is online now   Reply With Quote
Old 04-01-2013, 05:09 PM   #3
Member
 
ericmunyon12345's Avatar
 
Join Date: Feb 2013
Posts: 55
Default

Shared neutral Question.


Well, what's going on is I have each circuit in each switch box (one controlling one switch in each two gang box). The fans only pull about 2 amps each, but a bit over 6 for startup. With four fans on each circuit, I split it like this so that startup draw would be on different circuits when each pair of switches is flipped. (The fans were set up exactly the same before, we just used the pull chain on each fan to turn them on/off.) I'm not joining circuits as long as I keep my lines/loads straight. It would just eliminate one white and ground wire between the switch boxes if I do 3 wire. So at the switches, yes the two circuits would be sharing a neutral, but I'd think this should be fine though it may required a double pole (shared handle) breaker.
ericmunyon12345 is offline   Reply With Quote
Old 04-01-2013, 05:27 PM   #4
Member
 
Join Date: Nov 2007
Location: Nashua, NH, USA
Posts: 6,867
Default

Shared neutral Question.


If you run a multiwire branch circuit, it must go all the way back to the panel.

That is, you may not combine two separate circuits (two 2 wire cables) up in the house to become a MWBC (one 3 wire cable) continuing further on (downstream) to additional switch boxes or outlet boxes.
__________________
Stop wasting time re-adjusting the pattern. Have several lawn sprinklers, one for each pattern.
AllanJ is online now   Reply With Quote
The Following User Says Thank You to AllanJ For This Useful Post:
ericmunyon12345 (04-01-2013)
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
Unused ground lead as neutral? ramatsu Electrical 13 01-10-2012 07:44 PM
G.E. panel neutral lug question. exhdo1 Electrical 3 12-07-2011 09:33 AM
Knob and tube neutral question gbwillner Electrical 2 11-07-2009 09:34 AM
Help if it's not too late!! Cyndi Electrical 255 10-10-2008 09:18 PM
Use a shared nuetral or not? That is the question. Cyndi Electrical 16 05-23-2008 02:59 PM




Top of Page | View New Posts

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