Everyone makes mistakes. Some are just funnier than others.
School of Hard Shocks
My dad was called to a vocational high school to run power to a new piece of equipment in the plastics shop, and he decided to take along his new apprentice, Mike, who was extremely energetic and willing to learn but a little hard to hold back. After they completed the new 3-phase cable/conduit run from the main panel to this new piece of rotating equipment, Dad and Mike energized it and left the cover off to check for voltage at the terminals. The instructor came over to test it but found that it rotated in the wrong direction. Dad asked Mike what should be done and reminded him it was a 3-phase system, and Mike instantly realized that all he needed to do was interchange two phase wires. But before Dad could get the words from his mouth, Mike had quickly reached into the still live piece of equipment with his screw driver. The resulting short circuit tripped the breaker, let out a little smoke, and produced a pretty loud bang that drew the attention of all the students in the room. Once he realized he was uninjured, Dad did his best to hold back a smile. Mike learned a lesson that day that he would never forget.
Winnipeg, Manitoba, Canada
Old Man River
Once when I was the foreman of a papermill job in West Point, Va., I had one of my older electricians trace some conduit from a motor control center we were replacing. As I said, he was an older gentleman, and his job was to find a good spot to tie the conduit into the new center. Well, when we started cutting the pipes and water went everywhere, we realized he had gotten confused and marked a 1-inch water line as the electrical conduit. The resulting flood shut down a major piece of equipment, and it was a costly repair, to say the least.
Illustrations by Clint Metcalf