electric switch for carver water heater Duett

Hi everyone. The electric switch for water heater works sometimes.Last week it tripped at a campsite, came home  put on hook up  heated water fine, a couple of weeks before had to switch on and off a few times then worked.  Any ideas?Is it a faulty wire? How do you get at switch? Thanks in advance for help.

Probably best that you have a qualified electrician investigate the problem.

Surely switch is assessable? Does the cover not just screw off with screwdriver. Fault could be at the element end. Can you get access from inside the van?. If not might have to come out.