Re: Builders...
I was doing a desk refit in an office that was getting some back-to-the-bricks TLC next door. A builder came along and asked to try his drill in a socket of the desk I was working on, it was "flaking out on me" he said, running for a few seconds then stopping. Being insufficiently caffeinated I told him "go ahead" and sure enough the SDS drill spun up then stopped. I managed to wake up sufficiently after seeing this happen to prevent him trying to plug his 1500W drill into the next 3A-fused socket along the desk's power strip...
There's a reason I carried a pack of 3A slow-blow 20mm fuses in my toolbag after that incident. I ran into a lot of dead sockets like that in regular desktop visits, usually at desks with a 3kW fan heater tucked underneath where the office manager couldn't see it.