by switch i mean the one that is fitted to the top of a shurflo pump from the factory, the part is approx 25 notes from williamson pumps and i keep blowing them, right my set up. i have a 450 ltr tank, a pipe comes from the tank to the pump, then from the pump to my di bottle, then from the di bottle to my hose then my pole, the pump is wired to the ciggerette lighter socket on my van, i have an inline fuse with a 10 amp fuse inline which never blows, i never run the van when i'm working so what is blowing the switch on the pump,it sounds like it works when ya switch it on but when ya connect the poles it just cuts out and doesnt deliver any water, i even took someones advice and put a return on the pump back to the tank but it lasted a day and blew, my system is ready for me to blow it up coz i cant keep chucking cash at it, what am i doing wrong guy,s, help me please