I think In one of my books it says to mount that on top of the car. And they recommend that you solder a 10 guage wire to it and run it to your steering wheel. Right where you put your hands. Basically so you can have your hands grounded to it. Then they say it is best to drive in a thunder and lightning storm. You get the best reading that way. Make sure there is a lot of lightning. Anyway, good luck.