Hi AllIs there a formula I can use to calculate the appropriate RCD size for acircuit? I am about to use an old electric shower supply to feed a 1.7Kwstorage heater. Its the only thing on the circuit (or is it a spur :-) andcurrently has a 30amp RCD on it.I assume 30amp is way too much for a little storage heater but how docalculate what to replace it with? Same applies to a circuit that I'mputting a hand drier on and so on...ThanksTony

RCDs aren't current dependant - although you need one of a suitablecurrent carrying capacity.I'd guess you mean an MCB?To work out the load, divide watts by volts, so in the case of your heater, 1700 ---- = 7.4 amps 230Normally, the MCB in the CU protects the house wiring. The fuse in eitherthe plug or the FCU (fused connection unit) protects the appliance -although if there is only the one appliance on the circuit - like say acooker or immersion heater, the MCU can protect both.

How to calculate RCD "size" ?

Jan 16, 2004 22 Replies

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Andrew Gabriel 22 years ago

That's it -- all one piece of porcelain though. If you're careful, you could have a wash and piss at the same time, but it might take a little practice...

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Andy Hall 22 years ago

There was a joke about a sailor and a marine involving that, but I can't remember it......

.andy

To email, substitute .nospam with .gl

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Andy Luckman (AJL Electronics) 22 years ago

Don't you mean "spin dry" ?

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