One nice way of doing things is to have the boxes
tethered to armored
flexible conduit (not BX, but sort of a plastic coated Greenfield), so
the box can move to the machine, and not the other way around. It is
quite legal.
RCS/RI is installing dual voltage locking receptacles (L14-30Rs), so that
most machines can be plugged in anywhere. Damn expensive, though.
Bill, make sure you include tidbits like these in the museum how-to.
-doug q, who's running the Prime from a custom 30-amp 5-20R quad terminated
extension cord