Earthing?

[Edward]

I can't see why anyone would want to separate wires of a circuit through different holes or not....

A practical question about wiring the 8 wires of a stepper in parallel:

For short run desk tests I normally join and solder each pair length as supplied to go to the respective A+,A-,B+,B- twisting it together along the way, as Neale mentioned above. But now I have to do it properly using 4 core screened CY cable, 1.5mm2. which I think is rated at a whopping 18A. Should I cut the motor cables as close to the motor source as possible, solder each pair to one of the four cores of the CY cable and use heatshrink on each joint, and then a bigger dia heatshrink to hold together the lot? This bulky point where all the cables join at the motor side, and the screening ends, isn't it a possible source of interference?

If so, is there a recommended best way to do this?

In terms of magnetic fields and interference, is it better to instead use 8 core CY cable all the way to the driver but of a smaller cross sectional area?

Edward