480Y/277V service for a commercial grow operation, but need 120V also. Tx?

[SparkyKurt]

I'm installing a 1200A 480Y/277V 3-phase service for a commercial grow project. The 480V 3-phase will take care of the A/C, Heat, and an exhaust motor. The lighting needed is all going to be 277V, but there are also several other loads that require 120V and maybe 208V or 240V depending on which kind of Transformer I use.

So that's the question. What kind of transformer should I use to convert the 480Y/277V 3-phase service into useable 120V for all the smaller loads? Should I go with a single-phase transformer with a 120/240V secondary and just use a regular house panel, or would it be better to get a transformer that would give me 208Y/120V 3-phase so everything is balanced?

My total single-phase load is only 76.3A, so I could use a 100A panel and be fine. Am I correct in assuming a 15KVA transformer is the right size?

 

[Beaches EE]

If your single phase load is that small and planned to stay that way, then a 480-240/120 single phase XFMR will work fine. 15kVA sounds reasonable enough for the planned load.

 

[electrofelon]

I did A similar thing:. 1200a 277/480. For most stuff, hooked up a 50 kva 480-120/240 single phase transformer for some 120 stuff, a few mini splits, and a few 240 lites in a starter room. The 480 service had enough extra capacity that I didn't care about the imbalance.

 

[SparkyKurt]

I did A similar thing:. 1200a 277/480. For most stuff, hooked up a 50 kva 480-120/240 single phase transformer for some 120 stuff, a few mini splits, and a few 240 lites in a starter room. The 480 service had enough extra capacity that I didn't care about the imbalance.

I did A similar thing:. 1200a 277/480. For most stuff, hooked up a 50 kva 480-120/240 single phase transformer for some 120 stuff, a few mini splits, and a few 240 lites in a starter room. The 480 service had enough extra capacity that I didn't care about the imbalance.

Why did you go with a 50KVA Tx to take care of your single-phase loads if they were as small as your post implied? I was thinking of going with a 15KVA transformer to feed a 120/240V single-phase panel or a 15KVA 3-phase Tx to feed a 208Y/120V 3-phase panel.

 

[electrofelon]

Why did you go with a 50KVA Tx to take care of your single-phase loads if they were as small as your post implied? I was thinking of going with a 15KVA transformer to feed a 120/240V single-phase panel or a 15KVA 3-phase Tx to feed a 208Y/120V 3-phase panel.

There is a decent amount of load: 5 mini splits and some grow lights making 50 kva appropriate - plus I found the 50 kva on eBay near by.....