Drivers,BOB and PSU are in a PC case, do i earth the case

[deannos]

Which cable are you referring to? While, in principal if the PSU is built to Class 2 insulation specs it is not necessary to earth it, I would recommend earthing everything. The point of not earthing the screen at both ends is to prevent currents flowing in the screen which could compromise the screening efficiency. If necessary a separate earth conductor could be included. inside the screened cable.

Russell.

The cable is 4 core screened and i have used this to connect the motors to the drivers and also to connect the drivers to the BOB