Reminds me a bit of a High Screwel <g> experience of mine in the electronics classroom. The instructor was absent and a room full of rowdy (nerdy?? ) boys were being supervised by a sweet grandmother substitute teacher. Someone (who was THAT?) connected a lytic backwards polarity on one of the lab power supplies and then sat back down at his desk. When it exploded like a firecracker , the sweet sub teacher ran out of the classroom.
Bri