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#211003 - 08/31/13 11:22 PM Switching the neutral
Stu T Offline

Registered: 03/17/01
Posts: 28
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)

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#211004 - 08/31/13 11:29 PM Re: Switching the neutral [Re: Stu T]
gfretwell Offline


Registered: 07/20/04
Posts: 9023
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


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