Secondary conductors off transformer

[rockman33]

I am installing a 2300 - 480v transformer to feed a 400 HP motor with a soft start. Since the soft start has its own 480 - 120 v control transformer is there any reason to run the neutral from the transformer? I will be running parallels #600 THHN feeders along with a the grounding conductor. Is there any thing I am missing?

 

[JoeStillman]

I would not run the neutral. There's nothing to connect it to.

 

[Cow]

I am installing a 2300 - 480v transformer to feed a 400 HP motor with a soft start. Since the soft start has its own 480 - 120 v control transformer is there any reason to run the neutral from the transformer? I will be running parallels #600 THHN feeders along with a the grounding conductor. Is there any thing I am missing?

Where is the OCPD after the transformer? Have you read article 250?

 

[augie47]

First, I would check with the soft-start manufacturer as some units aren't compatible with ungrounded systems.
Secondly, take a look at 250.21(B).

 

[iwire]

I am installing a 2300 - 480v transformer to feed a 400 HP motor with a soft start. Since the soft start has its own 480 - 120 v control transformer is there any reason to run the neutral from the transformer? I will be running parallels #600 THHN feeders along with a the grounding conductor. Is there any thing I am missing?

You do not have to run the neutral but you will still have to bond XO at the transformer assuming this is a wye secondary.

 

[Smart $]

First, I would check with the soft-start manufacturer as some units aren't compatible with ungrounded systems.
Secondly, take a look at 250.21(B).

I don't believe he's running an ungrounded system... just not running the neutral. However, assuming a 2300V - 480V transformer, there is some question as to where the service point is located. If on the secondary side, any grounded conductor is required to be brought to the service disconnect. If on the primary side, one secondary terminal (X0 for 480Y/277V, X4 for 480/240, or X1, X2, or X3 for corner ground) can simply be bonded to ground at the SDS transformer and nothing else need be done.