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#127812 - 01/08/02 08:08 PM 3 phase voltage readings  
aldav53  Offline
Member
Joined: Aug 2001
Posts: 545
Chandler, AZ USA
I'm doing a job at a auto repair garage that has a 400 amp 3ph panel. Reading the voltages I got 120v to ground on all 3 phases and between phase A & B it read 215v, B & C was 215v, but A & C was 0 volts. I have never come across this before. Also not sure why I got 215v between phases instead of 208v or 230v. Transformer problems? Any ideas? Thanks..
Al D


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#127813 - 01/11/02 07:45 AM Re: 3 phase voltage readings  
sparky  Offline
Member
Joined: Oct 2000
Posts: 5,311
Al,
drop a phase? x-former crapped out? check the draw on yer motors....single phasing should pop a few OL's ??


#127814 - 01/14/02 11:08 AM Re: 3 phase voltage readings  
aldav53  Offline
Member
Joined: Aug 2001
Posts: 545
Chandler, AZ USA
I found the problem last week on the wrong 3ph voltage readings. The customer had some so-called electricians out to do some work previously and they shorted something and blew one of the 3 legs (Phase A) at the meter where the panel was fed from, and they could'nt figure it out so they tied the circuits that were off to breakers on the other working phases just to get it working.
The reason I was getting reading on all 3 phases is it was being backfed through some load. Hard to believe someone could do this and then cover it up and leave it because they couldn't figure it out. It was a new Meineke Muffler business and wasn't open yet so the customer would'nt have noticed more problems until later.


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