ECN Forum Forums General Topics of the Trade General Discussion Area Transformer hookup?

The wye secondary XO is the neutral/ground.

H1,H2 or H3 to XO = 120 volts. It should be on the transformer connections plate.
If you are feeding it to a panel you can bond XO to the panel grounding device.
No need to bond XO to the frame of the XFMR if it feeds a panel. You can bond them in the panel. If it feeds a disco, then bond XO to the frame and grounding electrode or other earth ground. You have a four wire secondary.