so, this is not nearly as dramatic, but I was at a busy hackerspace (新车间) swapping out the brains of an electric doorbell to replace the chime with an arduino s

so, this is not nearly as dramatic, but I was at a busy hackerspace (新车间) swapping out the brains of an electric doorbell to replace the chime with an arduino sound trigger - crossed a wire while plugged into mains and the the whole 220v side of the doorbell explodes in sparks while a dozen people on their laptops are plugged into the same surge protector. No harm done, mea culpa. A more experienced hacker comes over with a huge bulky 1:1 transformer for isolating circuits and says “if you’re going to hack on mains, plug into this” after some inspection of the burned circuitboard, I realized all the parts I need are on the undamaged 5V side of the board, so it worked fine on USB power anyway, but I was grateful for that hackerspace spirit of “that was stupid, here’s the tool you’re supposed to use“