CK Tools :) The professionals choice when it comes to Electrical Tools
This official sponsor may provide discounts for members

Discuss Switched neutral or not? in the Electrical Forum area at ElectriciansForums.net

K

ktech

Welcome to ElectriciansForums.net - The American Electrical Advice Forum
Head straight to the main forums to chat by click here:  American Electrical Advice Forum

Can anyone point me to the part in the regs that explains when the neutral needs to be broken for isolation.

I'm looking in the case of a three phase sub board main incoming switch - when to use 3 and when to use 4 pole. And isolator switch for fixed appliance, again 3 phase - linked neutral or 4 pole switch.

I seem to remeber that if you have PME this has some effect due to the supplier not been able to guarantee the neutral is at earth potential?
 
CK Tools :) The professionals choice when it comes to Electrical Tools
This official sponsor may provide discounts for members
J

johnnyb

  • Thread Starter Thread Starter
  • #2
Don,t know where you got that from mate, in my personal opinion i think its always better to use 4 pole, as the neutral being a phase conductor i think its better to break it on isolation.
Especially when its an appliance you know you are safe from any feed backs off somewhere else.
 
M

maddfridge

  • Thread Starter Thread Starter
  • #3
Can anyone point me to the part in the regs that explains when the neutral needs to be broken for isolation.

I'm looking in the case of a three phase sub board main incoming switch - when to use 3 and when to use 4 pole. And isolator switch for fixed appliance, again 3 phase - linked neutral or 4 pole switch.

I seem to remeber that if you have PME this has some effect due to the supplier not been able to guarantee the neutral is at earth potential?
hi there

look at 537.1.3 / 1.4 etc :)
after all neutral is a live conductor:p

cheers
 
G

Guest123

  • Thread Starter Thread Starter
  • #4
hi there

look at 537.1.3 / 1.4 etc :)
after all neutral is a live conductor:p

cheers
I see what your saying, but 537.1.2 states that in a TN-S or TN-C-S system the neutral conductor need not be isolated or switched where it can be regarded as being reliably connected to earth by a suitably low impedance.

Big spanner in to vital works!!

P.S, just reading down the page it says the same thing again in 537.2.1.1 - neutral need not be isolated or switched in TN-S or TN-C-S.
 
Last edited by a moderator:
J

johnnyb

  • Thread Starter Thread Starter
  • #5
Yeh but don,t you think its always better Lenny, regardless, don,t you think its safer option .
 
G

Guest123

  • Thread Starter Thread Starter
  • #6
As a personal preference I do like to isolate all live conductors, I was merely giving the OP some definitive answers from ol' red as per his query.
 
K

ktech

  • Thread Starter Thread Starter
  • #7
Thanks for the pointers. It just occurred to having needing a 63A isolator and the wholesaler only having a three pole one in stock.
 
J

johnnyb

  • Thread Starter Thread Starter
  • #8
tell the wholesaler to get a 4 pole in mate.
 
Bulk Workwear - Clothing Suppliers for the Whole Forum Network
This official sponsor may provide discounts for members

Reply to Switched neutral or not? in the Electrical Forum area at ElectriciansForums.net

Top Bottom