It's minor but very related.

Two years ago (before I found out about this place and started reading up on safety and proper work procedures) I was changing a 20-amp/120-volt air conditioner socket on a dedicated circuit.

I threw the breaker, opened the box and undid the mounting screws. I reach into that box like a greedy little kid with a cookie jar to pull the socket out.

~~~~~~~~~~ZAPPP!!!!~~~~~~~~~~ and my arm jerks back all numb leaving me sitting all confused there for a couple of minutes.

I had opened the wrong 20-amp breaker!!!! I was in a rush and idiot me NEVER bothered retesting the socket to make sure it was totally dead.

Moral of the story is always take your time.

Test device. Open breaker. Test device again. undo the cover plate, touch your tester probes to the contact screws just to make sure. Proceed with your work. Sure it takes me twice as long to change a device now, but it beats getting bit. [Linked Image]