480Y transformer from POCO question

[Theflashelectric]

The power company is supplying a 480Y 3P transformer.



I’m only familiar with delta/Wye style.

Then I will be installing a transformer on the inside to get a 208/120 3P. Typically I have always done 480/277 delta to a 208/120Wye.
Can I still install a 480/277 delta after my main 480volt panel coming from the source to feed my 208/120 panel?




Should I get more info from the power company.

 

[Cederbee]

If you are planning on having line-neutral loads on the secondary side of the service, I imagine a neutral would be needed.

 

[electrofelon]

I would get clarification whether they are indeed providing ungrounded or corner grounded (might be referred to as delta or 3 wire) vs standard 480/277 wye. Unless you have something weird going on, you will want the wye even if you have no L-N loads.

 

[texie]

Unless this is some highly unusual situation, the POCO will be supplying a grounded 480/277 Y service. As such you need a neutral to the service equipment per 250.24(C) regardless of not having any line to neutral loads. Lack of a neutral presents serious safety issues as it is the fault return path.
The wording and improper terms used by the OP indicate to me that he is in over his head and should seek qualified assistance.

 

[LarryFine]

Then I will be installing a transformer on the inside to get a 208/120 3P. Typically I have always done 480/277 delta to a 208/120Wye.
Can I still install a 480/277 delta after my main 480volt panel coming from the source to feed my 208/120 panel?

Yes. That the source has a neutral has nothing to do with your delta primary. Carry on as usual.

By the way, "480/277 delta" is an oxymoron.

 

[Carultch]

The power company is supplying a 480Y 3P transformer.

I’m only familiar with delta/Wye style.

Then I will be installing a transformer on the inside to get a 208/120 3P. Typically I have always done 480/277 delta to a 208/120Wye.
Can I still install a 480/277 delta after my main 480volt panel coming from the source to feed my 208/120 panel?

You can certainly connect a customer-owned transformer that has a 480V delta primary, to your 277/480V wye service. In fact, it is the most common way that it is done, to derive a system for 120V loads. You could use a wye:wye transformer if there is a specific reason you'd need it, but there is an cost advantage to the delta primary in this application. It is a more common topology which means manufacturing economies of scale, and it omits the neutral wire on the primary circuit.

It ends up being no different than if you connected any other load to the 277/480V service, that has zero load on the neutral. Obviously, you wouldn't connect a neutral to the delta primary of the transformer. There would be no place to even connect it.