Question, I'd like to use a relay with e-stop to cut power rather than relying on Mach and the PC.

Can anyone recommend a suitable relay and is a solidstate relay best for this application?

Also when wiring for a star ground do you wire the earth cable for the mains cable to this and all other earths from PSU's, cable shields etc. into the star ground? I'm really trying to avoid ground loops but am unsure if this is good or bad practise.