Re: Working space
I looked through NFPA 70E in the section on PPE and approach distance for unqualified persons,I saw no mention of taping off the boundary. But if I was using hazaard tape, it would make sense for it to follow the standard colors per ANSI Z535.4-1998, IE Red, orange, yellow depending on the hazard. I belive there is a new version on Z535 in the works and it will require pictographs, in place of "Danger" and so on.
There is a couple of web sites that focus on OSHA, OSHA Doctor is one of them, you might try there.