The Wye/Wye

[wtdoor67]

Most are 120/208 or 277/480. There are others out there I know. I have seen a few other types.

The following is from a GE transformer connections book copy righted in 1970.

Y-Y connected transformers, excepting three-phase core-type units, are not capable of supplying an appreciable single-phase load from line to neutral without a serious shift in the position of the neutral, owing to the fact that the corresponding primary currents of such loads, flowing through the primaries of the unloaded phases, magnetize them. This statement is primarily true for Y-Y connected single-phase units and shell-type three-phase units. Core-type units, however, may, on account of the interlinking of the magnetic fluxes in the three legs, give tolerably good results under conditions of single-phase loads from line to neutral or unbalanced electrostatic charging currents.
-------------------------------------------------------------------------

I have only worked significantly on about 5 properties. No where have I worked that it was not stated that you "never float the Wye/Wye".

I believe that it would work on strictly 3 phase as I have hooked several Delta/Wye and floated the secondary Wye. Oil field only. From that I'm sure that the reverse would work. But NEVER where single phase load might be involved.