https://drive.google.com/open?id=0Bx...k1KVjFtWWd3a3c

He's taken 1-2mm out the side of a conduit with a ring main cable
inside. As far as I can see, not actually punctured! Bottom hole barely
grazed it.

I'd marked out cable occupancy on the wall to the left for the fan
heater. I did not explicitly mark out the rest of the wall.

A heart attack followed by a measure of relief... And a reiteration of
safe zones.