4 pole ATS, switch neutral

[anbm]

We can use 3-pole ATS instead of 4-pole ATS, switch neutral
... if the load doesn't require a neutral wire, is it correct?

 

[chris kennedy]

I can't think of any NEC requirement that says a 4 pole "shall" be used.

 

[anbm]

It does not, only when we need for grounding purpose.

 

[David A Engelhart]

I thought there were certain 700 or 701 systems that required a switched neutral, but I can not find it.
If a switched neutral is used, the grounded neutral from the generator must be connected to the grounding electrode system of the building as it is the a separatly derived system.

 

[augie47]

I have seen very few switched neutral ATS systems and my if my memory serves me correctly an engineer informed me once he had specified a switched neutral do to the main distribution have GF protection.

 

[jumper]

I have only done a few ATS installs and none of them switched the neutral. None of the manual ones either.

 

[hillbilly1]

I have installed a lot of them, as Augie has posted, it's usually when the service is groundfault protected. Nearly all of the Blue boxes use them, as with the Orange box, they usually do not.

 

[chris kennedy]

I have installed a lot of them, as Augie has posted, it's usually when the service is groundfault protected. Nearly all of the Blue boxes use them, as with the Orange box, they usually do not.

Does this mean Blue is 1000A and Orange is less?

 

[iwire]

When GFP breakers are involved it is good design to use switched neutral transfer switches.

If you do not it is possible for current flow on the EGC/GECs to trip out the GFP.

 

[hillbilly1]

Does this mean Blue is 1000A and Orange is less?

Most Orange boxes use the 6 switch rule, and have 2-600 amp mains to avoid the ground fault protection, the older Blue boxes use the same with 5-6 switches with varible sizes of mains. But a lot of the newer Blue boxes have single mains now.

 

[chris kennedy]

Most Orange boxes use the 6 switch rule, and have 2-600 amp mains to avoid the ground fault protection, the older Blue boxes use the same with 5-6 switches with varible sizes of mains. But a lot of the newer Blue boxes have single mains now.

Thank you sir. FWIW, 1000A and up 4 pole SDS are well designed here. The EE's seem to drop the ball on trivial items yet the SDS's seems to be something they have a good grasp of.