what does that do, click, CLUNK
Not a DC but a whole college campus. Back in the late 80's I did electrical engineering at college. As part of an assignment we had to go in to the main electrical switch room and draw and lable what we saw. Anyway there was a very large airbrake style breaker the ones that look like a one arm bandit fruit machine, now I knew what it was and NOT to touch the large handle. BUT something in my head said I wonder what that does and I flicked the small flapper swich on the side of the air breaks case. CLUNK air break tripped and the entire college lost power! It was the FECKING breakers test button that I pressed!
My mates all helpped out and said my A4 ring binder folder had accidently knocked the switch. For the rest of the term the college clock and bell was out by about 10mins as thats how long it took to get the power back!