From the sounds of things this is for the electric side of your hot water heater. Our 2011 Elk Ridge 27RLSS has 2 switches to turn the electric side. Like jimtoo said, make sure you have water in the hot water heater before you turn it on. One of our switches like jimtoo said, it located on the panel where you check the level of the tanks, it is red, & is like a light switch. The other one is located outside, next to the hot water heater, & has a cotter pin in it to lock it in the off position. To turn it on, just remove the cotter pin & flip the switch to on. Both switches have to be on for it to work. For the most part I leave the outside switch on during the camping season, as I've always got water in the hot water heater unless it's winterized.