Mike, how common is Ground Fault Protection over there? Would if be reasonable to specify that a MechMate can only be connected to a fused outlet with GFI? Out here that would be the de facto situation.

On a factory floor, it isn't common at all. Per NEC code, it is required in newly built or (re)wired home garages, kitchens, baths and outdoor receptacles. But most older garages don't have GFI and they are basically "grandfathered in" since they've already been inspected. I believe a dedicated, hardwired device in a garage, such as an air compressor may be exempt from the GFI requirement, but I won't swear to it. The NEC code is open to interpretation by the building inspectors and different municipalities may use different editions as their code book. It's a real mess really.

As far as requiring GFI protection, it would certainly be a good idea. Considering the wiring is being done mostly by nonprofessionals and that wiring is in motion, it would be a small price to pay to avoid the potential shock hazard. Despite the best grounding efforts it would still be possible to have exposed wiring a person could come in contact with, without it necessarily grounding out.

Installing a GFCI
 

Installing a GFCI : an article found on the web.

(Ground Fault Circuit Interrupt)

I would like to offer this as a possible main power/E-Stop schematic. I am know the symbols are not standard, but I think you can get the idea. What we have is the a relay similar to what you have spec'd earlier except with a 24V control, and next to that is a 24V transformer. When the on button is press, the relay will transformer will turn on, energizing the relay, witch will then continue to feed the transformer after you have releaced the button. The benefits to this setup are, the power will remain off after a power outage, less high voltage wireing running through all the moving parts, and it also gives you a good source of power for iluminated switches.

Brian, 24V control is common in industrial electronics, but I am loathe to introduce yet another voltage into the control box - we have enough confusion in there already. The other benefits you mention are already present:

"The benefits to this setup are, the power will remain off after a power outage, less high voltage wireing running through all the moving parts, and it also gives you a good source of power for iluminated switches."

Our latching circuit also stays off after a power outage and illuminated switches for 115V/230V are also easily available.