I think that the most important part that a beginner would miss are the side effects of the current being switched. The side effects are 'rising' the ground and clicks (RFI pulses) which can reset or glitch the controller. Otherwise 30A is not a large current imho. Peter -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads