I've known someone to receive shocks from a switched fused spur plate. It was foolishly (in my opinion) placed in a swimming pool changing room, which is constantly very humid. When I went there after being told someone had been shocked, my neon screwdriver was lighting brightly when touching the top of the switch. I removed it and took it apart and found a nice black track running from the permanent live side contact to the top of the switch which I believe was caused by moisture and muck from fingers slowly creating a path for a small arc to cross, eventually creating a dark black path etched into the plastic. The switch was beaded with water when I got there, and I was amazed they'd used FCUs for the hairdryers there designed to be operated by the swimmers. I blanked off the FCU box, no way was I going to put another into service. My worry is the same condensation build up will occur repeatedly in bathrooms from hot baths and showers, and eventually create the same kind of tracking.
In Spain it's normal to have light switches and sockets anywhere in bathrooms (my parents' combined switch and socket is right next to the sink), however the switches over there are huge, the entire 2 & 1/2 inch square rocker switch front would need some tracking before voltage found its way to fingers - maybe that's their intention? In all the years I lived there, I never encountered small rocker switches like ours in the UK. Never knew of anyone getting a shock from one either, and being next to the sink, it's common for damp hands to knock the light off before leaving.
. Doesnt make anymore mess either, just filling in hole for old switch.
