600A 480/277 3PH to 100A 240/120 1PH Panel?

M

msilva94

Member
Location
Allentown, PA, USA
Occupation
Electrical Engineer
I have a situation where a client purchased a pre-fabbed shack that comes with a 240V 1PH Panel.
Initially I was thinking to transform the 480V to 208V 3PH when I realized the existing panel is 240V 1PH.
I'm fresh, so I'm not entirely confident on how to move forward with this situation, I was wondering if I can still provide a 30KVA XFMR that transforms 480 3PH down to 240 1PH? Thank you
 
If you have any line-to-line loads, if they can handle 208v, you're okay.

Just use two lines and a neutral like you would for 120/240v.
 
LarryFine said:
If you have any line-to-line loads, if they can handle 208v, you're okay.

Just use two lines and a neutral like you would for 120/240v.
Click to expand...
From the transformer?
The HVAC Unit states it can be wired in 208V, there's only 2 lights in the shack and a hand full of receptacles, but the Main CB on the SubPanel is called out as a 2P 120/240V.
Can you explain what you mean by two lines and a neutral like I would for 120/240V? Are you saying it's quite possible to connect the SubPanel directly to the 480V Panel?
Nevermind, I believe you meant to use 2 lines of the 3ph xfmr.
 
msilva94 said:
From the transformer?
The HVAC Unit states it can be wired in 208V, there's only 2 lights in the shack and a hand full of receptacles, but the Main CB on the SubPanel is called out as a 2P 120/240V.
Click to expand...
That's fine. 208v is less than 240v, and your 120v loads will see no difference.

Most equipment ratings are maximums, not absolutes.
 
I would not install a 208 three phase transformer unless each of the three windings can be somewhat evenly loaded.
So I would either replace the single phase panel with a three phase panel or install a 480 : 120/240 30kva single phase transformer.
 
tortuga said:
I would not install a 208 three phase transformer unless each of the three windings can be somewhat evenly loaded.
So I would either replace the single phase panel with a three phase panel or install a 480 : 120/240 30kva single phase transformer.
Click to expand...
Thank you, I'll be moving forward with a 480 to 240/120 1ph xfmr - it's what I decided on after the brain fuzzies went away. I haven't experienced many 240V services so the brain fuzzies attacked hard.

I appreciate this forum and it's experienced members a lot.
 
You mentioned a 30kva... you won't find that in single phase... the closest will be a 25kav abut only only need to size the transformer to supply the load so even a 25 will be overkill.
 
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