Grounging LT (X4) on FPE transformer

[dj98hd2]

I have a customer that has a 240-volt 3-phase machineconnected to a FPE 30kva 480-240/120LT T43T30E which has a X4 tap (lighting tap) in it which is for 120-volt. They have not needed the 120-volt option untill now. My question do you ground/bond the X4 tap the same as you would on a Y transformers XO tap?:-?

 

[nakulak]

I believe this is the wiring diagram that comes with the unit

http://www.federalpacific.com/outlinedrawings/t43t30e.pdf

the only way to get 120 is to use x1 or x2. the drawing appears to indicate x1, but I would check the case to make sure there are no factory bonding straps already installed