The key thing with grounding, is to avoid ground loops, which you potentially create anytime a screen had more than one ground connection.

However, in power wiring, ground loops aren't likely to be a problem. The point of grounding in power wiring is to contain noise. A ground loop there is unlikely to cause any problems. A prime example is if you wire up a VFD as per most manufacturers recommendations, you ultimately create a ground loop in the wiring, as the motor is likely to be grounded through the machine.

It's in signal wiring, especially low voltage i.e. 5V, where ground loops are far more likely to cause problems.