Oh - and to explain the numbers on the contactor
VAC - volts AC
FLA - Full Load Amperage
LRA - Locked Rotor Amperage
Res Amps - resistive load amps
The contactor can operate load voltages of up to 630 volts AC. The FLA at all voltages is 30A, and the LRA i.e. max startup or stall amperage, varies from 183A at 240V to 110A at 630V.
It's the FLA that's important, usually the LRA is way in excess of your breaker - or even house supply, and it's the surge startup amps that would cause the contactor to melt.
Resistive load amps are relevant if the contactor is driving a resistive load e.g. a water or baseboard heater, rather than an inductive load like a motor or compressor.
I would recommend buying an enclosed contactor like the Siemens one, rather than an open one like the White-Rogers. Ants can get into exposed contacts and although they get vaporised, their carbonised remains make a poor contact and shorten the life of the contactor
Ants aren't quite as bad as mice though