Boost Transformer Wire Size

[LarryFine]

Isn't your last name actually Fine?

It actually is.

 

[ptonsparky]

We are reconnecting 3 - boost transformers for a 3 phase machine that was relocated from another building, and had been installed by some other contractor originally. The source voltage is 120/208v 3 phase 4 wire and we are boosting to 230 volt 3 phase 3 wire. The 3 transformers are to be connected in a wye configuration with H4 from each xfmr connected to the source neutral. Previously, the neutrals were connected using a #10 wire size which I believe should be the same size as the 3 phase conductors (1/0). Although the load is 3-phase and there may not be much load on the neutral wires, I can find no exceptions in the code to allow the reduction in wire size. Therefore, I think we should change those # 10's to 1/0.
Any Opinions???

Does kind of say "3 - boost transformers" Catalog indicates single phase buck boost transformer so it must be three individual single phase buck boost transformers. Looks like a wye - wye configuration to me. I assume d something else entirely. Thanks for the education - again.

 

[BigBillEQ]

They are 3 - separate transformers that are connected by field installed wiring through conduit nipples into a 6" x 6" wireway.

 

[dsteves]

They are 3 - separate transformers that are connected by field installed wiring through conduit nipples into a 6" x 6" wireway.

Good morning.

Kind of odd, but what the heck?

3 separate single-phase transformers - for sure you'll need full-sized conductor between the H4's, then.

Dan