ECN Forum Forums Technical Discussion Electrical Theory and Applications Delta to Wye

To summarize, there are 2 flavors of a 240V Delta:

240V 3-Phase 3-Wire (Straight delta)

120/240V 3-Phase, 4-Wire (Hi-Leg Delta)

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The 208 Volts that coincidentally exists between phase B and neutral (the ki-leg) is NEVER usable. No 1P CB's on phase B.

Radar

Other comments from E-C.net members are welcomed if you see this as inappropriate advice...

Given no grounded-circuit conductor from the serving transformer connected to a neutral bus in the three-phase panel, it is not usable in 4-wire delta service, and not intended to serve 120V branch circuits. In basic terms, a 240V-primary transformer is needed to furnish 120/240V 1ø 3w (connected to two phases in the 3ø panel.)




[This message has been edited by Bjarney (edited 06-24-2004).]

That makes sense BJarney. A grounded conductor was pulled with the three phases.
Phase to phase is 240v Cphase to ground is in the 208 neighborhood.
I was confused with the xfmr installation in the beginning because I wasnt 100% on the Delta. It is clear now the other sparky wasnt either.
Most installations I see are 4wire w/ high leg.
Some reason though they only pulled a #2 with the 500's for Grounded conductor. Really limits the single phase circuits unless size is upgraded.