Originally Posted by THenne1713
Many/most have a (almost hidden) rocker switch that kills the 12vdc control voltage, and this switch is on outside near top of outside access panel? Killing 12v stops gas or electric operation.
That would be for a Suburban water heater. The OP has an Atwood. (He doesn't say so, but the picture shows an aluminum tank, which is the Atwood, now Dometic).
My Bigfoot Trailer came out of the factory with an Atwood combo gas/elec water heater, but the gas control and the fault light were on the stove hood, and the elect switch (which is 12v DC telling the circuit board to tell the relay to close and allow 120v to the element) was located in a very open horizontal surface and was an extremely easy to operate switch. It was the illuminated type but that doesn't do any good when you throw a jacket on top of it and accidentally turn on the switch with the jacket hiding it. (which is exactly what I did with a dry tank. thankfully I caught it rather quickly and the heat element still works.
The stove hood had extra switch positions on it, so I ran the additional wire in the harness bundle behind the cabinets, opened up the areas that had to be opened to run the wire with the rest, pinned it thru a connector, and installed a lighted switch on the stove hood for the electric side of the WH and added a lighted switch for the gas side also.
You'd have to be a real klutz to accidentally switch these on. Stove hoods with switches, tank levels, etc were apparently fairly common in the early/mid 2000's.
Last pic shows what I did before I got around to running the wire, tracking down the proper size switches and re activating the original gas circuit and warning light.
I would not be able to use the pressure switch idea as I don't turn on the pump unless I am actually using water, and I never use the city water connection, always drawing out of the tank.