Often times the lighting in a body shop will be florescent, LED, induction, etc - something with a ballast or power supply. Very likely the on/off times of your average device (like the Viking) will be too fast to have a visible effect on the lights.

Also, Ernie brings up a good point regarding the safety implications of switching the lights on and off in a work environment.

Best bet will be to use a strobe or similar for the visual cue.