Hi Guys;
I got a nasty scare (but a relatively minor shock) a number of years ago while I was a student in college. I was helping the theater stage manager replace several bad autotransformer dimmers in a large stage lighting switchboard. We had turned off the power to the entire board at the MDP feeder breaker in the basement of the building, then taped a warning sign over the breaker (no way to LOTO, unfortunately)and locked the door to the room behind us. While I was virtually inside the switchboard from my waist up, the stage manager noticed several pilot lamps light up on the board, indicating that the power had been turned back on. He warned me at about the same time a heard a dimmer start humming about two inches from my left ear. As I backed out of the board, I brushed against another dimmer which shot me backwards to the wall behind the switchboard. Quite discouraged by this, the SM and I went down to the switchgear room, found the breaker had been closed, and the warning note crumpled on the floor. We turned the breaker off again, then hid in a corner of the room where we could observe the MDP. A few minutes later, a secretary entered the room and attempted to close the breaker again, whereupon we stopped and detained her until the campus police arrived.

It turns out that a wiring fault existed which led to the air conditioner (20 a., 220v.) in her office being connected to the feeder breaker for the stage lighting service (300a., 120-208v. 3ph. [Linked Image] ). Four things happened immediately thereafter; 1) The secretary was instantly fired, 2)The lock to the switchgear room was changed, 3) The MDP was modified so that the breaker could be locked out, and 4) the air conditioner circuit was reconnected to a different power source.

Yes, we should have had the college electric department do the work, but they refused because they "had never worked on that kind of thing before". [Linked Image]

Mike (mamills)

[This message has been edited by mamills (edited 08-26-2002).]