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George George is offline
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Default 440 volt three phase question

On 5/29/2010 6:29 PM, Don Klipstein wrote:
In , John Grabowski wrote:

*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.


What you are describing sounds to me like a 240V "star" system with high
leg, a variant of Y. Two of the phases are 240V center tap with the center
tap connected to neutral. That provides four 120V legs. The third is 240V
with one end rather than the center tap of that transformer's winding
connected to neutral to provide the "high leg". It is possible to use the
center tap of that to provide a fifth 120V leg.


The secondaries are connected in delta. One of the secondaries has a CT
that is used as the neutral for 120 VAC loads.