cable shielding and relays

Hi all,
I am just trying to finish up my router/plasma project and there are
two things I can't seem to find any info on.

1. I'm using a shielded wire for my motor connections - do I ground
that wire at the machine or at my controller box?

2. Does anyone have a source for a safe (to my equipment), simple to
make or premade relay setup for turning on spindles, etc.?

Thanks a bunch,
Chris Coleman