Ooh! I can! I can! Pick me! Pick Me!
Simply put, when the system trips, regardless of the present switch positions, the exhaust fan must come on/stay on, the intake fan (if there is one) must turn off/stay off, the under-hood lights must go off (if required), any electrical appliance(s) under the hood must be de-energized (but some say not for dry-type extinguishers), a horn/strobe must be activated (if required), the gas must shut off (sometimes mechanically (plumber's job), sometimes electrically (may have a manual-reset box)), and sometimes, if present, a building-wide alarm system should be triggered.
There is no one way to wire everything. You must know how the system is set up: 1 fan, 2 fans, 1 switch, 2 switches, directly switched or contactor-controlled, 120v or 208/240v, etc., etc., etc. The more you can tell us, the more we can help.
I just did one today, and it was a tough one. Single switch for both fans, but it was a 2-pole switch, had lights and a gas valve with reset box, a horn/strobe, and a tie-in with the building's alarm system. I did all the power wiring using only one microswitch, freeing the second one for the alarm trigger.
