Should be a toggle switch in water heater compartment. May be a wire safety pin in it. If there is remove pin and flip switch to on. Do so only if hooked up to water and tank is full or you could burn out electric element.
Leave water heater switch on control panel off as that is only for propane mode. We use very little propane other than when in transit for fridge and for BBQ.
2008 Cardinal 30RKLE 5th wheel sold
2006 Rockwood 2607, 2001 Traillite
55 nights 2009, 53 for 2010
44 for 2011, 38 for 2012, 35 for 2013, 51 for 2014