Hello.
I have a 420 watts heater and want to connect it to a 240 volt 8 amper programmable thermostat. Is the thermostat going to work or blow up?
Iceman.

Power = Volt times Amps

Amps = Power divide volts

Amps =480/240 = 2 amps

Looks like you good to go without any blowups.

If this is 1420 Watts, then 1420/240 = 5.9 amps.