Apologies for what must seem a stupid question but I don't know where else to ask. There are two switches in the cupboard with my hot water tank - from reading elsewhere one of them is an immersion heater and should only be switched on if I want an extra blast of hot water and the other should be left on all the time. The thing is I can't tell which is which.
The switches are side by side and near identical - both have the word 'on' written on the top of the actual switch and 'fuse' written vertically down the fuse but no other labels.
The left hand switch has a wire that runs down, across the floor of the cupboard and up to a box on the water cylinder (second picture). The right hand one has no visible wires and whatever it links to must be inside the wall.
I'd like to know which switch I can turn off.