we dont need one we always make sure we have site power ......we always tell them its going to be better for the enviroment if they give us a 3 phase installation and so long as you have 3 phase you can easily run 240v you just need to make a special little lead then away you go , 3 phase is a piece of piss to have installed. but on saying that we're doing a carillion site and they said they would install it for £175 so we told them to stick it up there chuffer , when we got to site there was 3 phase for the silo which the brickie was only using for one tub of gear first thing and the lift engineers had an installation and they wasnt due on site for another 6 weeks .....we've only used our genny 2-3 times this year and we been spraying everyday