Hi All

Is there a formula I can use to calculate the appropriate RCD size for a
circuit? I am about to use an old electric shower supply to feed a 1.7Kw
storage heater. Its the only thing on the circuit (or is it a spur :-) and
currently has a 30amp RCD on it.

I assume 30amp is way too much for a little storage heater but how do
calculate what to replace it with? Same applies to a circuit that I'm
putting a hand drier on and so on...

Thanks

Tony