do i need an external RCD if my property has no external electrics?

Answer 1

No, but an RCD helps protect the internals as well.

If you have an uetral fault and its touching an earth, it will generate heat. THe first time you find this might be when the fire brgade are at your house when you come back from shopping. Whith an RCD it will trip because the return current is not balanced with the live ( i.e. there is some residual current in the earth ).

Also an RCD wil trip if you touch the live, so you will end up with a 30mA shout and a mind "oh, what was that ?" rather than a 80A "OH ****, WHAT WAS THAT ! "

Unless of cause, you are taking the p*** and know that an external RCD refers to outside the consumer unit, rather htan integrated.

Answer 2

By external electrics do you mean outside the house?

There is usually only one RCD on any installation and a main fuse, these should be clearly labeled inside the consumer board. If it's a new installation, everything is labelled clearly and an RCD will be fitted - RCD protected circuits will be grouped. You may also find two RCD's, a 30mA for the sockets and a 60mA for lighting circuits, though this is quite rare (I think).

On older installations RCD's were not mandatory and were generally only used for outside sockets, but it is a good idea to at least protect the sockets in your house.

Simply put an RCD is a good idea and if you do not have one, get one fitted, I do not fully understand your question, I just provided this as a brief summary - every house has different needs.

If in doubt though it always pays to seek a qualified electricians help to clear things up, after all electricity can be dangerous and it will never cost that much to get qualified advice.

Answer 3

residual circuit breaker
this knocks the power of in 0.03 Milli sec so when you cut through the cable of your hedge trimmer you LIVE so its up to you
there are no laws stating you have to use them
most extension leads you buy now have them fitted as standard