Kill switch question

[Steve Harvey <stevenh@execpc.com>]

Hello list,
I found a proximity switch (normally closed) that I would like to
install in-line on the ignition wire. In order to make it work properly,
a metal object would have to be presented in front of the target which
would open the circuit and not allow voltage to the ignition. Has anyone
used such a switch?
Steve Harvey
Milwaukee
P.S. RAIN! I'm cutting my grass 3 times a week. If this keeps up, I'm
thinking of building a very large boat in the backyard.