Adroga:
I believe that WW Grainger has a line voltage t'stat that is rated for 5KW at 240 volts.
I venture you are talking about a 5KW unit heater? Most mfg have a t'stat kit for their models, or a relay pkg to use a low volt t'stat
Or, if you have to be creative...a definite purpose 2 pole contactor/relay rated for 30 amp minimum, with a coil voltage of your choice, and a corresponding voltage rated t'stat should cover your needs.
Please check the Ca Electrical Code.
