Not saying that this is right, or the only way to do it, but it is working for me...

I use 4-way XLR. CY cable from the motor has its braid soldered to the shield terminal in the XLR plug. Because I don't trust the socket to make a sound electrical connection to the powder-coated cabinet, I run an earth wire inside the cabinet from the earth terminal on each socket to the star earth. Each XLR socket has CY cable to the stepper driver with the shield connected to the socket's earth tag (along with the wire to the star point). I should probably not have daisy-chained the socket earths to each other and then to the star point as each should have had its own wire (probably). I have had no noise issues with my cabinet wiring. At least, not as far as I know.