That brings back another memory. We used to have electric baseboard heaters. The previous owners put in central air, and they used the old baseboard heater slots in the panel for the new bigass breakers to power the heat pump and such. All the wires were just sort of stuffed out of the way in the panel, and it was a real mess. Meanwhile, every room still hads the heaters and thermostats. They just didn't work.
Not a single baseboard heater in the entire house worked. They were useless, ugly, and in the way. So I started ripping them out and replacing them with new baseboards. One, two, three, you get the ideas.
After testing a dozen dead heaters, I got lax. The one in the dining room was still hooked up. I was using tin snips to cut the romex back far enough to get the baseboards on. I melted a nice divot right out of the snips, but didn't feel a jolt in my hand thanks to the rubber handles. Yowza. SNRRT!! simultaneous with an intense blue arc.
So I tested every subsequent header seven ways from Sunday before I tried that little trick again. I got off pretty easy. It could have been a truly electrifying experience.