# Help with 480v multiple voltage design



## joebanana (Dec 21, 2010)

Just install two xfmrs.


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## telsa (May 22, 2015)

Bare#1 said:


> Some..but Not much experience designing a multi voltage build outs. And I definitely want it all 100% safe!!..oh.. and to pass the AHJ's inspection.
> 
> Current setup: I've got a Older 480v 600A main service/600A OCPD. I've got 288v from ground, line to ground on all feeders/CCC's ( I was testing off of my feeds for my 400A OCPD.)
> 
> ...


I'll skip the rest of the details.

Your OP makes me feel that you've got virtually zero experience at this scale.

Your scheme would come off as total hair ball to any inspector... even if you could satisfy Code.

Everyone expects to see panelboards not kludge ups inside this or that NEMA1 can.


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## McClary’s Electrical (Feb 21, 2009)

bare#1 said:


> some..but not much experience designing a multi voltage build outs. And i definitely want it all 100% safe!!..oh.. And to pass the ahj's inspection.
> Current setup: I've got a older 480v 600a main service/600a ocpd. I've got 288v from ground, line to ground on all feeders/ccc's ( i was testing off of my feeds for my 400a ocpd.)
> big question: Is this delta and not 480/277 ?
> I have seen on 208y 3p services the 208 leg being 215v. ( with no load). But never a 10v volt difference.. I'm pretty sure the 277v lighting would be damaged by this increased voltage.. ( pop mov's in ballasts ? )
> ...


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## Cow (Jan 16, 2008)

joebanana said:


> Just install two xfmrs.


Yep, sounds like a guy that needs two tranny's....:whistling2:

The rest of the questions a code book would probably answer.


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## RePhase277 (Feb 5, 2008)

You certainly could have 288 volts from a 277 volt system. The real check is to see if you actually have a neutral in your main equipment, or look at the transformer(s).

Yes you can get a 480 to 480/277 transformer if you need to. No you can't use the neutral of the 208/120 transformer to get a neutral for your 277. Because not only is it against code, it also simply wouldn't work unless you actually have a 480Y/277 volt main.


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