On May 27, 4:03�pm, "Stormin Mormon"
wrote:
I've had the moment to work on 440 volt roof top heating and AC.

Once in a while, need some power to run a 120 volt device. Is it 120
volts from one leg to ground?

(Yeah, I could just check it. But I was on the roof yesterday, and not
sure how long until I get to another roof.)

--
Christopher A. Young
Learn more about Jesus
�www.lds.org
.

With any three phase sytem (assuming it's symetrical) the line volts
= phase volts divided by root three
ie in your case 440/1.73 =254
This is because the phases are 120 degrees apart.
This is the voltage that would appear between phase and ground or
phase and neutral.
However it's not a good idea to run electrical equipment between
phase and ground as there is a good chance of electrocuting yourself
or someone else. The someone else could be some distance away too.