It's a good thing they drill a bunch of crap into our heads day in and day out. I was troubleshooting a mysterious Autopilot problem, and found some loose terminals on some relays. I got my screwdriver and went to tighten them. Then, somehow my right forearm touched a relay closer to me, and my left hand was holding onto an LRU. I was immediately clamped. Luckily, though, the new airman I was with killed aircraft power within seconds. Holy crap that hurt. I got lucky today, that was some good ol 115 VAC 400 Hz going right across the chest.