I had equipment at a colo facility -- that had a (licensed, bonded, not fly-by-night) electrical tech accidentally drop a tool into the main bus connecting main

I had equipment at a colo facility -- that had a (licensed, bonded, not fly-by-night) electrical tech accidentally drop a tool into the main bus connecting mains, generators, and batteries. They are lucky they were able to walk away, but the facility was dark till someone could get in there and give the power equipment the green light.