Was called to look at an electrical problem. I looked at the panel that
seemed to be the culprit, determined it to be a 240 v. 3-phase
(probably) panel with a few breakers that were causing problems. One
side of one of the power lugs was completely burned off, and the breaker
on the other lug was making sizzling sounds. Turned it off pronto.

The panel has 3 big fat wires coming into it. Measured between all of
them: 240 volts between all 3, which makes me think it's 3-phase (3
legs, equal voltage).

But here's the weird thing: there are some 120-volt outlets apparently
attached to this panel that function correctly. When I turned some of
the breakers off, the outlets lost power, so I assume that they're
directly powered from this panel.

How can this be? How do you get 120 volts from 240? (No big fat
transformers visible anywhere.) What am I missing here?

In case anyone's wondering, no, I don't mess with 3-phase power or any
other kind of heavy-duty commercial/industrial stuff. My customer's
reaction was "I'll call a licensed electrician", which would have been
my advice. It appears the entire panel needs replaced.

I'm just curious about this situation.


--
Personally, I like Vista, but I probably won't use it. I like it
because it generates considerable business for me in consulting and
upgrades. As long as there is hardware and software out there that
doesn't work, I stay in business. Incidentally, my company motto is
"If this stuff worked, you wouldn't need me".

- lifted from sci.electronics.repair