I once had to move a light switch/back box 50mm to the right. I removed the face plate and saw that the cable exited via the top of the metal back box. I didn't want to isolate the lighting circuit because I didn't have site lights with me. I started tapping away at the plaster with my Japanese cat's claw. Bang! I went through the live and earth.
I then discovered that the cable went up through the top of the metal back box, and ran down the right hand side of the box. Annoyingly, the incident left a slight dent in the cat's claw. Other than the "bang" noise, and the lights turning off, I didn't experience any shock. I have long wondered if that was down to the fact that my Timberland Pro boots were supposedly rated at 650v.
I then discovered that the cable went up through the top of the metal back box, and ran down the right hand side of the box. Annoyingly, the incident left a slight dent in the cat's claw. Other than the "bang" noise, and the lights turning off, I didn't experience any shock. I have long wondered if that was down to the fact that my Timberland Pro boots were supposedly rated at 650v.