When do Neutrals need to be switched?

[MaintenanceSpark]

Sorry if this is a silly question but I can’t get an answer from colleagues as it’s a “I dunno”. So I thought I’d ask here!

Some of our TPN DB’s have a 3 pole main switch with a block for the neutral. Other TPN DB’s we have here have a 4 pole main switch which switches the neutral.

It’s the same for our machine isolators. Some have a 4 pole rotary switch and others have a 3 pole rotary switch with a connector block for the neutrals.

When do we need to switch neutrals & why?

Apologies again if it’s a silly question or something I should already know. I’d like to learn.

Thanks guys.

 

[mickegh]

Neutral is a "live" conductor so should generally be switched

Also even with TN where the neutral is reliably at earth potential it can be safer to switch

 

[MaintenanceSpark]

Neutral is a "live" conductor so should generally be switched

Also even with TN where the neutral is reliably at earth potential it can be safer to switch

Cheers mate. Whenever I change an isolator in the future I will always replace it with a 4 pole rotary switch isolator then.

 

[mainline]

Neutral is a "live" conductor so should generally be switched

Also even with TN where the neutral is reliably at earth potential it can be safer to switch

If the OP is talking about 3 phase, then the N is normally solid linked.
If the Neutral is switched, then the 4 pole switch should be late disconnect and early make.

 

[Risteard]

If the OP is talking about 3 phase, then the N is normally solid linked.
If the Neutral is switched, then the 4 pole switch should be late disconnect and early make.

Indeed. It can be more hazardous to break the neutral in this scenario.

 

[MaintenanceSpark]

Thanks guys. I’ll keep the neutral in a connector block link and keep it unswitched.

 

[MDJ]

Neutral is a "live" conductor so should generally be switched

Also even with TN where the neutral is reliably at earth potential it can be safer to switch

Id disagree, if a neutral hangs and single phase circuits connected in a TPN board then 400 volts can go across 230 volt connected equipment, seen it happen and generally as mentioned by Risteard can be hazardous

 

[mainline]

Id disagree, if a neutral hangs and single phase circuits connected in a TPN board then 400 volts can go across 230 volt connected equipment, seen it happen and generally as mentioned by Risteard can be hazardous

Hence, the need for late break early make isolator.