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

Topic Options
Rate This Topic
#211003 - 08/31/13 11:22 PM Switching the neutral
Stu T Offline
Member
Registered: 03/17/01
Posts: 27
Loc: Stamford, CT
Can a standard 3 pole disconnect switch be used to switch 2 phase conductors and 1 neutral. My concern is the lack of accurate synchronization of the blades making to their respective contacts. If the neutral blade makes last it could cause over-voltage in the phase to neutral loads. Seems like the neutral blade would have to make 1st and break last. What about a 3 pole molded case circuit breaker ?
What do you think?
Thanks in advance.


Edited by Stu T (08/31/13 11:24 PM)
Top
Work Gear for Electricians and the Trades
#211004 - 08/31/13 11:29 PM Re: Switching the neutral [Re: Stu T]
gfretwell Offline


Member
Registered: 07/20/04
Posts: 9039
Loc: Estero,Fl,usa
It is "legal" but certainly a design issue, for exactly the reason you brought up. Whether a millisecond or so of unbalanced load would hurt anything is really a question of what the load is.
It is also a situation where you fail very "hard" if the neutral fails to make totally.
I would avoid it if at all possible.
_________________________
Greg Fretwell
Top

Member Spotlight
Member Since: 04/03/02
Posts: 6778
New in the Gallery:
SE cable question
Featured:

2017 NEC and Related
2017 NEC
Now Available!

Shout Box


Who's Online
0 registered (), 63 Guests and 8 Spiders online.
Key: Admin, Global Mod, Mod
 
New in the Gallery:
SE cable question
 
Top Posters (30 Days)
Admin 47
HotLine1 43
gfretwell 19
Ruben Rocha 12
Trumpy 9
 
Newest Members
Scotto, Freecrowder, clee512, Jdscott2005, FAIZAN

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