The Electrical Contractor Network

ECN Electrical Forum
Discussion Forums for Electricians, Inspectors and Related Professionals

Books, Tools and Test Equipment for Electrical and Construction Trades

Register Now!

Register Now!

We want your input!

Featured:
   

2017 NEC and Related
2017 NEC
Now Available!

   
Recent Posts
Forum Software Upgrade coming soon...
by Webmaster
01/17/17 09:41 PM
Re: Fabricating Guards out of Lexan?
by frank
01/17/17 04:11 PM
Would ELV branch circuits be a good idea?
by gfretwell
01/17/17 01:26 PM
Why cables look like they do
by Texas_Ranger
01/17/17 12:33 PM
100% breakers?
by Texas_Ranger
01/16/17 06:13 AM
New in the Gallery:
Desk-mounted "power-board"
Shout Box

Top Posters (30 Days)
HotLine1 20
Webmaster 19
gfretwell 13
ghost307 12
Trumpy 12
Who's Online
1 registered (Webmaster), 0 Guests and 62 Spiders online.
Key: Admin, Global Mod, Mod
Topic Options
Rate This Topic
#99425 - 11/02/05 06:05 PM 215.4B
Steve Miller Offline
Member

Registered: 08/30/01
Posts: 322
Loc: Loudoun Cty, VA
This isn't new to 05 but here's the question:
As we read this it disallows a paralleled feeder to a sub panel (from a main dist panel) if the sets are in 2 or 3 pipes (one set per pipe). We have many panels fed by two EMT pipes that originate at a breaker in a dist panel, where each contains all the phases, a neutral and a grond. We're obviously missing something here. Maybe we aren't defining "common neutral" properly. Or maybe we have a lot of illegal panels.
Your input is appreciated.

Top
2017 / 2014 NEC & Related Books and Study Guides
#99426 - 11/02/05 08:45 PM Re: 215.4B
gfretwell Offline


Member

Registered: 07/20/04
Posts: 9062
Loc: Estero,Fl,usa
The reference to common neutral means you are only running one neutral back to the panel for multiple parallel phase sets. If you pull a neutral with each set you can split them up in separate raceways.
It is just an inductive heating problem because all neutral current would be in one pipe with the outgoing current split up among the others.
_________________________
Greg Fretwell

Top
#99427 - 11/03/05 03:22 AM Re: 215.4B
Steve Miller Offline
Member

Registered: 08/30/01
Posts: 322
Loc: Loudoun Cty, VA
We follow that but here's what threw us: look at the cut & paste from the code ... what does the NEC mean by "ALL conductors of ALL feeders". Doesn't that seem to indicate every individual conductor of each set? Or do they interpret each set as a separate feeder? Or, again, are we just interpreting it wrong?

"Where installed in a metal raceway or other metal enclosure, all conductors of all feeders using a common neutral shall be enclosed within the same raceway or other enclosure as required in 300.20."

Top
#99428 - 11/03/05 04:27 AM Re: 215.4B
resqcapt19 Offline
Member

Registered: 11/10/00
Posts: 2209
Loc: IL
Steve,
If you have a grounded conductor in each raceway, you don't have a common neutral and the section that you cited does not apply. The section for your installation is 310.4.
Don
_________________________
Don(resqcapt19)

Top
#99429 - 11/03/05 02:51 PM Re: 215.4B
Steve Miller Offline
Member

Registered: 08/30/01
Posts: 322
Loc: Loudoun Cty, VA
I see we were just interpereting "common neutral" wrong. Thanks for the input.

Top


ECN Electrical Forums - sponsored by Electrical Contractor Network - Electrical and Code Related Discussion for Electrical Contractors, Electricians, Inspectors, Instructors, Engineers and other related Professionals