Suburban OEM On/Off Switch for electric is in outside compartment below gas valve
Because of its location outside many 'owners' add a 120V AC switch inside....wired in series with OEM switch
Atwood older models (2003/previous) had the electric on/off switch on backside of water heater on cover that was over the element. PITA to get to so many 'owners' also added a 120V AC switch wired in series with OEM switch
For both Brands BOTH switches have to be ON for element to get energized. Only one needs to be off to turn element off.