Was there a reason you grounded the switch? Like maybe there's an internal pilot light? I'll bet your problem is right there. If there's two termnals on the switch, one goes to battery through the fuse, the other to the lights. If there are 4 terminals, the switched are wired as before and the pilot light is connected to the lights and the other side to ground. 30 amps will make something warm! SteveV