Re: AC Mains panel.... What on earth do I have here???

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Original poster: "Jim Lux by way of Terry Fritz <teslalist-at-qwest-dot-net>" <jimlux-at-earthlink-dot-net>

Light industrial/office spaces are often fed with 208/120Y.. this means that
the phase to ground/neutral is 120V, and the phase to phase voltage is
208V.. Those are nominal voltages, and at the panel will often be somewhat
higher, especially if measured when load is light (say, when everyone has
gone home?).. (I had a system which was nominally 480V phase to phase, but
when load was light was well over 510V)

The other scheme, less common, is a 240 delta with the center of one side of
the delta grounded.  Here, two of the phases will read 120V to ground, and
the other one will read higher.
----- Original Message -----
From: "Tesla list" <tesla-at-pupman-dot-com>
To: <tesla-at-pupman-dot-com>
Sent: Wednesday, March 19, 2003 6:21 PM
Subject: AC Mains panel.... What on earth do I have here???


 > Original poster: "Paul Kidwell by way of Terry Fritz
<teslalist-at-qwest-dot-net>" <tmb-at-ieee-dot-org>
 >
 > Hi Everybody,
 >
 > I'm part owner of an engineering firm. I was looking at our
 > AC service to see what I had available and I came across
 > something that had me a little confused. Our office outlets
 > all measure real close to 120 VAC but we have three phase wiring
 > coming into the back of out building. I'm no great expert
 > when it comes to polyphasic power distribution, but seeing a
 > nice 120 VAC at my outlet, 240 at some of out heavy
<mondo snip>