You do not mention what type of system you are using and drives etc, you really have to know the exact nature of the present power supply connections, your 60v supply may be completely isolated at present but you are most likely getting the reading you do by using a typical high impedance meter.
For the 60vdc common to be connected to Earth ground, the transformer ac secondary has to be isolated from ground, if using a linear supply.
Switching supplies are generally isolated anyway.
Al.
CNC, Mechatronics Integration and Custom Machine Design
“Logic will get you from A to B. Imagination will take you everywhere.”
Albert E.