ECN Electrical Forum - Discussion Forums for Electricians, Inspectors and Related Professionals
ECN Shout Chat
ShoutChat
Recent Posts
Underground phone and coax depth?
by gfretwell - 02/08/23 06:34 PM
Al Hildenbrand - Minneapolis - obituary
by Bill Addiss - 02/03/23 07:38 PM
Violation?
by renosteinke - 01/27/23 09:52 PM
Does NEC 551.71 (F) apply to dwellings?
by BigB - 01/20/23 10:46 AM
New in the Gallery:
Burger King crown sillyness
Burger King crown sillyness
by wa2ise, December 11
240/208 to a house
240/208 to a house
by wa2ise, October 9
Who's Online Now
1 members (gfretwell), 126 guests, and 9 robots.
Key: Admin, Global Mod, Mod
Previous Thread
Next Thread
Print Thread
Rate Thread
#211003 09/01/13 01:22 AM
Joined: Mar 2001
Posts: 27
S
Stu T Offline OP
Member
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.

Last edited by Stu T; 09/01/13 01:24 AM.
Joined: Jul 2004
Posts: 9,791
Likes: 14
G
Member
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

Link Copied to Clipboard
Featured:

Tools for Electricians
Tools for Electricians
 

* * * * * * *
2023 National Electrical Code (NEC)
2023 NEC Now Available!
 
* * * * * * *

2020 Master Electrician Exam Preparation Combos
2020 NEC Electrician
Exam Prep Combos:
Master / Journeyman

 

Member Spotlight
Samurai
Samurai
Fl.
Posts: 46
Joined: May 2007
Top Posters(30 Days)
triple 2
Popular Topics(Views)
303,296 Are you busy
232,254 Re: Forum
217,014 Need opinion
Powered by UBB.threads™ PHP Forum Software 7.7.5