No Neutral

[Keithmac]

I have an external RCD socket on an RCD supply, the way I see it is if one fails at least there's a backup!.

 

[JohnW2]

I have an external RCD socket on an RCD supply, the way I see it is if one fails at least there's a backup!.

Indeed, there's absolutely nothing wrong with 'belt and braces', and the very minor inconvenience of perhaps having top reset two RCDs after a fault is trivial.

There are two or three other reasons for having an outiside socket RCD protected, even though there is another upstream RCD ...

1...As eric has said, one the socket can have a 10mA RCD, whereas the house one will usually be 30mA
2...RCD sockets almost invariably have 'active' RCDs, which mean that they have to be reset after a power cut, avoiding the risk of some machine springing back to life after a power cut. That is not true of the 'passive' RCDs usually found in a CU.
3...Related to (2), most ('active') RCD sockets will not switch on if the socket does not have an effective earth - thereby affording another level of protection against possible faults.

Kind Regards, John

 

[ericmark]

So you bought the wrong one then!

If having a 30mA RCD feeding a 30 mA RCD is wrong, why does the BS7671 insist you do that with supplies to caravans and boats? I will admit for outdoor use the 10 mA RCD makes more sense, and today when more and more homes are already RCD protected one would expect to find most plug in RCD's to be 10 mA, however it seems hard to find them for sale.

When I first fitted RCD's in my house, I had to fit them in a separate board which fed the old fuse boxes and also changed the fuses for MCB's there was no readily available box so RCD is together with the MCB's and as time has gone by the fuse box gave way to the consumer unit and the consumer unit have altered to take two RCD's and changed from plastic to metal, and before the need was identified in BS7671 the units were simply not available.

I am sure at some point some one will realise ovens do not have wiring able to handle 45 amp and we will be told where a stand alone oven is fed from the cooker 45A supply it needs a 16A fuse, and all of a sudden we will see 16A FCU's for ovens likely built into the cooker connection unit. Most of domestic advancement seems to be driven by BS7671.

Having moved house this year, I have seen what happens when DIY takes hold, three FCU's and 13A socket from a fuse box and consumer unit all feeding the central heating, C&G 2391 lecturers would never dream of including that as a fault to be found by students, it seems the safer we try to make things the more ways are found to make it dangerous again.

I opened the electric cupboard to see a nice new consumer unit, however when I came to work in the house, turning it off did nothing, house supplied from old wilex fuse box hidden between ceiling and roof.

I would hope this is not the case with the socket in question, however it does seem strange it did not trip, I have opened fuse boxes to find the isolator shorted out before now, only one pole was doing anything, and reading the replies I begin to wonder, has one RCD been by-passed? Some thing seems wrong, we I think have exhausted the normal things, so looking at some thing unusual.

The last ELCB-v I have found was 2 years ago, we did not use them for long, but still some around, and all it needs is an earth wire to short out the monitor and it stops working. I hope nothing wrong, but I think @mjtefc9 was correct when I raised the thread, it would ring alarm bells with me. Had he said I got a shock, that could be understood, but get a shock with RCD fitted and it did not trip, I would also wonder why.

Our first action is to press the test button, and if the RCD had stuck, that would likely free it off, so now you will never find it. I would be asking my son to bring the RCD tester next time he visited to test it. But if it had stuck then likely we will never know, as by now it has likely freed off, so we will never find the fault.

 

[winston1]

I have an external RCD socket on an RCD supply, the way I see it is if one fails at least there's a backup!.

By the same reasoning is every socket in your house an RCD one?

 

[JohnW2]

By the same reasoning is every socket in your house an RCD one?

Presumably not - although the risk-averse amongst us might even consider that (given the apparent fairly high rate of in-service failure of RCDs).

However, as I said, there are at least three reasons in addition to 'redundancy' why an RCD socket (or RCD adaptor/plug) might be favoured for outdoor equipment.

 

[Keithmac]

By the same reasoning is every socket in your house an RCD one?

No, but then again my Hot Tub isn't connected to them either..

 

[plugwash]

why does the BS7671 insist you do that with supplies to caravans and boats?

I always assumed they did this because they knew full well that there was no way they could make every caravan park and marina (including those abroad) compliant, nor could they make every caravan and boat (including those visiting from abroad) compliant.

 

[mjtefc9]

Got the tester and tested from the socket.... the 63a RCD works fine.. tripping from the socket at 25ms and tripping at 18ma..

Must of been static and my girly hands..

Thanks for the replies lads