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Re: DATACENTER: quick question



> > since if you connect the legs together you'll get a voltage greater than
> > 480.
> 
> Actually, I believe that if you pull from between 2 hot leads on a 480V
> 3phase, you get 277V.
> 

Wrong..  phase-to-phase voltage on a 480V service is just that, 480V.
phase-to-neutral on the other hand is 277V. 
this assumes that the service is wired in the Y configuration.

If you simply tie 2 phases together, without a load in-between, you will get
fireworks (or not, depending on how solid the connection is.)

I remember when a stagehand who didn't know what he was doing, wired 
2 120V legs of a 3phase 120/208V service together to a terminal on a 220V
outlet. it didn't blow up, it just instantly blew the 400A main breaker,
when he turned on the 20A branch circuit. (dead short). 
scared the s**t out of everyone at the time.


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