Its a metal (stainless steel) casing with a mirror door, has a canopy
over the door with 2 low voltage downlighters recessed into it. The
lights are operated via a rocker switch at the top rh *side covered in
a rubber membrane. The whole thing is shiny mirror like metal finish
inside and out. I have an isolator switch mounted on the wall in the
room behind it. It's above a wash hand basin in my downstairs shower
room- where I shave.

With the door open, as I put my hand in to get my shaving foam, I get
a small electrical shock, on the back of my arm, just below my elbow,
where it touches the corner of the open door! It's a constant 'buzz' -
not painful, but uncomfortable and obviously worrying!

How can I go about finding the fault? It happens when the isolator
switch is on or off! I'm wondering if the unit is faulty or has a
fixing nicked a cable in the wall? It's been up for a couple of Years
and only when the missus mentioned getting the same shock have I
thought I'd better get it resolved