3 phase 3w 480 panel

[Arkansas74]

We have some contractors that came in to install 2 480 v 3 phase panels for motors only. They are saying we have to have a neutral but the The panels will not need neutral must one be installed if it is only running 3 phase motors only? This panels will be for motors only. We have always put in 277/480 but the company just wants 3w 3 phase 480

 

[jumper]

A neutral/grounded conductor is only required at the main service equipment, not at any downstream panels if not needed.


250.24(C) Grounded Conductor Brought to Service Equipment.
Where an ac system operating at less than 1000 volts
is grounded at any point, the grounded conductor(s) shall
be routed with the ungrounded conductors to each service
disconnecting means and shall be connected to each disconnecting
means grounded conductor(s) terminal or bus. A
main bonding jumper shall connect the grounded conductor(
s) to each service disconnecting means enclosure. The
grounded conductor(s) shall be installed in accordance with
250.24(C)(1) through (C)(4).

 

[tom baker]

No neutral required but there must be an EGC.

 

[augie47]

DISREGARD THIS POST..I SOMEHOW THOUGHT THERE WAS A TRANSFORMER INVOLVED !!!!!!As noted above there is no requirement for you to have a neutral. Your 480 v output can be ungrounded or corner grounded. If it is ungrounded you will need to comply with 250.21(B), If you have drives involved in the controls, you might want to discuss the supply voltage with the drive manufacturer. Often drives do not care for ungrounded or corner grounded systems.

 

[GoldDigger]

As noted above there is no requirement for you to have a neutral. Your 480 v output can be ungrounded or corner grounded. If it is ungrounded you will need to comply with 250.21(B), If you have drives involved in the controls, you might want to discuss the supply voltage with the drive manufacturer. Often drives do not care for ungrounded or corner grounded systems.

I am confused. It sounds like this is supplied from the same POCO service, which is a grounded wye. So the delta circuit that they run from that point outward is not going to be either ungrounded or corner grounded. The neutral will just not be there.

I saw no mention of a separate POCO service or an SDS transformer in the OP's post. Can you clarify that Arkansas?

 

[augie47]

I am confused. It sounds like this is supplied from the same POCO service, which is a grounded wye. So the delta circuit that they run from that point outward is not going to be either ungrounded or corner grounded. The neutral will just not be there.

I saw no mention of a separate POCO service or an SDS transformer in the OP's post. Can you clarify that Arkansas?

As the younger generation said:" "My Bad"
I edited my post to "disregard".. My mind plays tricks on me.... I saw transformers that were not there.. Thanks for questioning

 

[Arkansas74]

Oh sorry yes it's is coming out of a 1600 amp y connected panel. No transform just setting 2 panels closer to where are new machines are. That why I can't see why they are saying we need a neutral.

 

[augie47]

Oh sorry yes it's is coming out of a 1600 amp y connected panel. No transform just setting 2 panels closer to where are new machines are. That why I can't see why they are saying we need a neutral.

and I agree..not needed... hopefully my errant post did not confuse the situation.