Quote from: NotFuzzyWarm on Today at 05:20:00 PM

Quote from: kaboler on Today at 04:00:22 PM

It's fairly common in the USA to have 480 phase to phase, and 277 from one phase to a neutral. There's usually a stepdown transformer to provide some 120/208 but then again, many things CAN run off 277/480. In commercial buildings that is.

Incorrect.
In the US, 480V service is the start of what is usually called "heavy power" and usually only available to industrial areas and large commercial developments. In large buildings it runs HVAC and is distributed throughout buildings to feed local 120/208V transformers.

The only common use for the direct 277V phase-to-neutral is for lighting fixtures designed to accept the high line. The 3-phase of course supplies large 3-phase loads. For all virtually all other '200V' devices, they top out at a maximum input of 240V and WILL quickly fail when fed anything over 250V.

we are a ware house built pre wwii
our concrete slab is six feet of poured concrete. the orginal use was building military gear for wwii.
we have many panels for power and
I checked we are 480 and we are 3 phase

we usually run at 219 to 229 on each and every phase.

however there are two really large transformers inside the ware house that may help the 480 turn into three phase 208/220

I know there are three legs labeled a,b,c and each 30amp feed has a,b or a,c or b,c gives us 219 to 229 pretty steady.