Neutral Lug not being used

[Shujinko]

I am dealing with an existing 480V/3-phase/3-wire electrical system (ungrounded delta). An automatic transfer switch (ATS) is being proposed to be added to this system. The ATS has three phases and an un-switched neutral. Since the existing electrical system is a 3-wire system the neutral branch lugs will not be used.

Is there any requirement in the national electrical code that requires you to use the neutral lugs if they are provided in equipment? Or can you just leave them unused?

Thanks.

 

[chris kennedy]

Is it service rated? If not will controls function without the neutral?

 

[Smart $]

No requirement. Leave them unused.

 

[Smart $]

Is it service rated? If not will controls function without the neutral?

I do not see the service rating as applicable to using the neutral connection (system is stated to be ungrounded, which means no neutral even from a service configuration)... but whether the ATS will function without a neutral is a great question.
:happyyes:

 

[Shujinko]

Is it service rated? If not will controls function without the neutral?

It is a service entrance rated disconnect.

 

[Shujinko]

Is it service rated? If not will controls function without the neutral?

Good question. The voltage code for the controller is for a 277V, which would require a neutral. This will have to change.

 

[chris kennedy]

It is a service entrance rated disconnect.

If the utility is providing a true 3 wire ungrounded system, then as Smart stated no requirement.
Did you look at the name plate on POCO's tranny?

 

[Shujinko]

If the utility is providing a true 3 wire ungrounded system, then as Smart stated no requirement.
Did you look at the name plate on POCO's tranny?

Yes, 4160 delta pri - 480V delta sec...both side ungrounded.

 

[texie]

I am dealing with an existing 480V/3-phase/3-wire electrical system (ungrounded delta). An automatic transfer switch (ATS) is being proposed to be added to this system. The ATS has three phases and an un-switched neutral. Since the existing electrical system is a 3-wire system the neutral branch lugs will not be used.

Is there any requirement in the national electrical code that requires you to use the neutral lugs if they are provided in equipment? Or can you just leave them unused?

Thanks.

I would be careful here. I would want to be certain that the ATS you are using does not require a neutral and is approved for use on an ungrounded system.