ECN Electrical Forum - Discussion Forums for Electricians, Inspectors and Related Professionals
ECN Shout Chat
Top Posters(30 Days)
Trumpy 3
dsk 3
Recent Posts
Feed to spa panel
by HotLine1. 06/25/17 05:28 PM
Weatherhead, POA, height?
by HotLine1. 06/24/17 02:37 PM
Windows 7 update problem
by ampherder. 06/21/17 07:01 AM
Norwegian power?
by dsk. 06/19/17 03:40 PM
Anyone ever take a Furnas A14D drum sw apart?
by gfretwell. 06/17/17 08:14 PM
New in the Gallery:
SE cable question
Popular Topics(Views)
238,238 Are you busy
173,456 Re: Forum
166,261 Need opinion
Who's Online Now
1 registered members (annemarie1), 63 guests, and 9 spiders.
Key: Admin, Global Mod, Mod
Previous Thread
Next Thread
Print Thread
Rate This Thread
#172578 - 12/21/07 02:56 PM AFCIs and MWBCs  
Tiger  Offline
Member
Joined: May 2005
Posts: 706
Crystal Lake, IL USA
Now that it's almost 2008, I'm giving serious consideration to installing several hundred AFCIs in the coming months. I had a thought that it might not be a code violation to tie the two ungrounded conductors of a MWBC (anywhere but on the breaker itself) and terminate it on one AFCI breaker. In my rather small home these two 15-amp circuits are 18 receptacles and lights, including a bath GFCI receptacle.

Dave


2017 / 2014 NEC & Related Books and Study Guides

#172579 - 12/21/07 03:25 PM Re: AFCIs and MWBCs [Re: Tiger]  
KJay  Offline
Member
Joined: Nov 2007
Posts: 763
MA, USA
Tiger,
I think that goes against good wiring practice regarding placing the two ungrounded conductors on opposite sides of the phase so the neutral only carries the unbalanced portion of the load as opposed to the full neutral current of both ungrounded conductors.
You would probably be safer and more code compliant, depending on the actual load, if you just used one side of the MWBC to feed all of the receptacles and lighting as one two-wire circuit.

JMHO


#175750 - 03/10/08 03:54 PM Re: AFCIs and MWBCs [Re: Tiger]  
KJay  Offline
Member
Joined: Nov 2007
Posts: 763
MA, USA
I see from their literature that Siemens now makes a two-pole combination AFCI cb for this type of application.
This is what I will need to use for my second floor bedroom circuits when the time comes as they were also wired with 14/3.
There may be other manufacturers making two-pole combination AFCI cb’s, but not sure.



Member Spotlight
JoeKP
JoeKP
Berkley, MA
Posts: 144
Joined: March 2008
Show All Member Profiles 
Featured:

2017 NEC and Related
2017 NEC
Now Available!

Shout Box
Powered by UBB.threads™ PHP Forum Software 7.6.0
Page Time: 0.010s Queries: 15 (0.002s) Memory: 0.7516 MB (Peak: 0.8754 MB) Zlib enabled. Server Time: 2017-06-26 19:11:07 UTC