I think that needs a bit of clarification, I believe the motor grounding you are refering to is the motor signal wires which should be shielded and yes, should only be connected at one end to avoid ground loop current etc. the shield should be connected to the common ground I mentioned in my previous post, but the motor frame should be grounded to the common ground point, This is an industry standard and is outlined in the wiring code for machine tools. Otherwise you will get the rusult that happend in this instance.
Al |