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John Grabowski John Grabowski is offline
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Default 440 volt three phase question

No, it's 220 more or less, to ground

It is entirely possible that the 440 volts is from a delta
configured
transformer that is not ground referenced or is corner grounded.
Point is that one shouldn't assume that the transformer that is
supplying the current is Y configured.
--
Tom Horne

It's only possible to determine how a three phase transformer is
connected visually. Ie by checking the connections.

You can make a very reliable determination with just a meter and
knowing
how 3 phase AC works.- Hide quoted text -

- Show quoted text -

That is completely wrong.

Really? So if we take the original question where the OP could have
used
their meter and as an example observed 480 VAC between each phase leg
and 277 from each phase leg to neutral we couldn't declare with
confidence that the source transformers were connected in "Y" ?- Hide
quoted text -

- Show quoted text -

If you read my post, If there are just three line connections brought
out, no, you can't tell whether its "star" or "delta" connected.


I did. You didn't describe that limitation but you could still be a long
way from completely wrong with only a meter if you only had access to
the phase legs. Since a "Y" connection neutral is always bonded to
ground I could still get the same readings I described by placing one of
the meter probes on ground.


If I was unsure of the voltage, what I would do is call maintenance
and ask.



*As I recall on a delta connection one of the phases will have a higher
reading to ground than the other two. On a Y connection the reading to
ground will be the same. In NJ, Public Service Electric and Gas will not
permit that high leg to be installed in the same panel as the neutral. The
NEC allows it though.