External rcd socket

[Tinkler]

If an external rcd protected socket is wired off an internal rcd protected circuit (ring-final) - in a fault situation, would both devices be tripped? Don't want to buy an external protected socket and find i still have to go in and reset the the CU rcd.

 

[Pensdown]

If your rings is RCD protected you don't need another one

 

[Tinkler]

If your rings is RCD protected you don't need another one

Yes, as far as protection goes. But if I'm in the garden and cut through the mower cable it would be easier to just reset the external socket rcd than go inside and reset the CU rcd which would have turned off many other appliances when tripped. The question is would both RCDs be caused to trip when cable is cut - if so, then it is pointless fitting an rcd protected socket for outside. Whereas if it means just resetting the external device then it is a good idea. So in the given situation what would happen?

 

[toasty]

It's commonly termed 'discrimination' and I'm afraid you are out of luck.

If the outside socket and the rcd in the consumer unit are both rated at 30mA (which I suspect they are) then it's anyones guess which will trip first. You'll probably find it'll be the one in the house most of the time though as it will already have some (albeit small) leakage through it thus causing a bias.

The best suggestion would be to try to use the RCD protected socket on a non-rcd protected circuit.

HTH
-Dan

 

[Pensdown]

As far as I know it would be hit & miss which one tripped first and it’s quite likely they would both trip.

 

[jondiy]

Yes, as far as protection goes. But if I'm in the garden and cut through the mower cable it would be easier to just reset the external socket rcd than go inside and reset the CU rcd which would have turned off many other appliances when tripped. The question is would both RCDs be caused to trip when cable is cut - if so, then it is pointless fitting an rcd protected socket for outside. Whereas if it means just resetting the external device then it is a good idea. So in the given situation what would happen?

If you cut through your mower cable, you're gonna have to go in the house to get your car keys to go down the wholesalers to get some new flex - so why your walking past your CU, you can re-set your rcd !!!! Any mower (or appliance causing leakage) would be useless & dangerous til repaired, so where's the convenience in being able to immediately restore the power????

 

[Spark123]

Please note doing this task is notifiable to your local area building control under part p of the building regs.

 

[Adam_151]

Chances are that the RCD won't trip at all, because there isn't often an earth in mower flex, but the rcd makes things much safer when you pick up the live end to go "oh ****, I should have been more ****ing careful"

 

[Steve]

I should have been more **** careful"

What 4-letter expletive should have gone there? Honestly, the autocensor must be working overtime, making bad words different lengths now as well!