Is interrupting the neutral along with the lines ever required?

[JMF]

Hi all. In a 4 wire 3 phase system, does the code ever require that the neutral be interrupted with the line conducors with a disconnect, either a 4-pole breaker or 4-pole disconnect?

I know that it is allowable to open the neutral, if all 4 poles open simultaneously, but is it ever required?

Thanks!
John

 

[Dennis Alwon]

Welcome to the forum...Been a long time but I believe it is required to switch the neutral on gas pumps.

 

[kwired]

Welcome to the forum...Been a long time but I believe it is required to switch the neutral on gas pumps.

Pretty much in all Class 1 hazardous locations AFAIK.

Any neutral to ground voltage present can spark if you touch them together and potentially ignite the mixture that caused the classification, if you happen to be servicing said equipment (which is a reason for having disconnecting means) to a point where you have exposed such possibility.

 

[JMF]

Thanks! I had forgotten about hazardous locations.

 

[kwired]

Thanks! I had forgotten about hazardous locations.

They make "switched neutral breakers" and that is just about all they get used for is hazardous location applications that utilize a neutral AFAIK.

 

[JMF]

Welcome to the forum...Been a long time but I believe it is required to switch the neutral on gas pumps.

Thanks! Been a long-time browser!