I saw a diagram once where a guy ran 2 wires down the hose and into the nozzle body, to a switch that he had rigged to work with the trigger. I believe he had some grounding problems with it though and got shocked pretty good??
Its easier to just hook all that stuff to a switch inside the pump body and have it activated when you lift the nozzle rest.
Others have gone so far as to install a tank and pump that will pump a liquid into a closed loop that circulates thru the sight glass. Its all in how far you want to go I guess.
