Hot water heater

On some models, there are two switches, with one inside. IIRC, you still need to have outside one in the on position, for the inside to switch on/off. If on the inside, it may be more likely to get switched on when empty, by an unknown person/kids.

I think you could run wires from outside switch, bypassing it to an inside switch, location of your choosing, if you really want to do it.

Jerry