Electric problem

[RatRibs73]

Morning all,

While renovating the lounge I preinstalled some flush sockets before plastering. This meant that I had two wires for each socket waiting to be connected to the ring main. Last night I joined the spiders underneath the floor and tried to connect everything up but failed and now I have no power on the ground floor. I'll try to give as much detail as I can and hopefully someone can give me some advice.

The consumer unit, which was replaced a couple of months ago, is in one corner of the room and the existing cable goes around three walls, in and out of the sockets on it's way and then exits into the cellar. Nothing complicated. The new sockets are close to the existing ones so all I did was cut into the existing cable in a couple of places and join it up to the new cable with 30Amp connector blocks. This "joined up" cable followed the same route around the 3 walls, in and out of the new sockets. Flicked the MCB on - no power! I checked all of the connector blocks and everything was tightly connected, then checked all sockets and they were wired up correctly. At about midnight I decided enough was enough and so reverted back to the original wiring by rejoining up all of the cuts I made with the connector block. Still nothing!! How hard is it to go wrong with a connector block? Is there anything else which could be causing the problem? Anyone got any ideas?

Cheers, Matt

[The3rd Earl Of Derby]

You have omitted to inspect the spiders as well?

personally I think your a cowboy by using connector blocks to lenghten the cable,how will these blocks be hidden?

[RatRibs73]

Used insulating tape, and placed them in ChocBlocks which are securely fastened to the joists. The cable either side of these is also secured with cable clips and they are all easily accessible. I'm a DIY'er and these meet IEE regulations so how can I be a cowboy?

[Bob Mannix]

You must understand that:

A) It's quite hard to go wrong with a connector block and you clearly have so you could not be described as a "competent person"

B) This sort of tale is part of the reason "they" got away with foisting part P on us

C) We don't like part P, ergo Sir BM's comments demonstrating that those who cause it to be foisted upon us are not liked either!

There is no magic involved. The circuit is either connected or it isn't. If there is no power at a socket, then there isn't a connection to it. You won't get any other advice than drawing up what you think you have made the circuit into and checking that is correct and then checking that that is actually what you have done. If you have a strong constitution, you could give us a link to some photos of your connections. Most people here will flame (if they think it is justified) and then try and follow with advice

[dom]

DO: Insulation and continuity test the wiring. If you don't have the means to, should you really be meddling?

DON'T: Use connector blocks - if, as I think you mean, it's "chocolate block" rather than junction boxes. In fact there should be no need for junctions, but continuous cable between sockets.

How you've managed to disable the existing sockets GOK - you should have a split ringmain at least. You need a continuity tester, not "suck it and see".

[Bob Mannix]

?

I have a feeling I'm going to regret this, but - used insulating tape for what, exactly?

[dom]

PMSL - yeah right - choccy block is just fine for fixed wiring - NOT!

Are you perhaps a Troll trying to wind us all up?

[Christian McArdle]

I wouldn't regard chocolate blocks wrapped in insulation tape to be acceptable. For this application, I would use crimped connections, with each conductor insulated with heatshrink tubing and then the entire sheath insulated with larger bore heatshrink tubing.

Alternatively, I would use chocolate block if it was (a) likely to remain accessible for inspection and (b) entirely contained within a suitable plastic enclosure.

As to why the circuit has stopped working, you probably connected a live to a neutral or earth somewhere and have blown something apart.

Christian.

[Ben Blaukopf]

I've got a hunch....

If you only disconnected the circuit at the MCB, then then it's possible that you tripped the RCD when cutting through the wire. I'm guessing that the new CU is a split load.

And if you finished at midnight it's also possible that you didn't notice the RCD had tripped, and didn't notice that any of the other circuits on it also had no power.

Ben

[RatRibs73]

Wrapped the connector block in it and then placed that into the chocblock. I must say that for a forum that is supposed to be for DIY'ers to ask for advice you all seem to be hell bent on making those of us who need help feel pretty stupid or telling us not to bother. I'm after some clear advice, not to be judged. Things go slightly wrong from time to time. Please don't tell me if I'm competent or not. I've wired plugs, sockets, light fittings many times without problems, I even wired my shower and CH in before the regs came in. No problems at all and all done within regs as I researched what I had to do. A connector block is not beyond me. This I can't explain though. I was hoping there was an experienced person on here who had come up with a similar problem and could give me some direction. I'm still waiting......All I seem to have got so far is opinions.

[RatRibs73]

Thanks, Christian. I agree, the connections are accesible and are contained in an enclosure which is why I decided to use the choc blocks. Can you expand on what you mean by blown something apart?

Cheers, Matt

[RatRibs73]

Checked it, Ben. RCD wasn't tripped. I ended up using an extension lead from upstairs to save the contents of the fridge freezer so have got power to other parts of the house.

Cheers, Matt

[dcbwhaley]

But it worked when he reverted to the original circuit so the RCB can't have tripped. Nor can he have damaged the MCB or the wiring. And I can't think of anyway of miswiring the new sockets that wouldn't trip the MCB or RCCB.

As for the spleen vented on the poor old OP: that is totally unjustified. He came on here for help with what I see as a very curious fault. If you can't offer advice then you should keep your mouths shut. Part P was not foisted on us because of people like the OP. It was foisted on us because of lobbying by industry groups who dislike losing work to DIYers. And that lobbying fell on the very receptive ears of a government that loves micromanaging everything.

[dom]

Ok -let's backpeddle a bit. Sorry for launching into one, the initial post gave me cause for concern. I can't see your installation, and usually chocolate block would only be used in an enclosure as some sort of wiring centre - I'm still not sure why you didn't use continuous cable runs. All connections would then be above floor level then and easier to diagnose.

The way forward is some sort of test instrument. Basic voltemeter and continuity testers are dirt cheap now (although wiring regs say you should insulation test as well).

Some long leads on your meter and you can probe to find where the break(s) are in the ring (whilst isolated of course), and that at least you can see a large resistance between the conductors. This should really have been done prior to re-energising the ring for the first time.

If that's all good, then we have to figure the problem is is in the consumer unit.

[Christian McArdle]

A live to neutral (or even earth) fault may have produced enough fault current to blow the MCB apart. Above a certain level (usually 6kA), it is possible to have a situation where the MCB trips, but burns out internally.

Christian.

[Christian McArdle]

Read again.

Christian.

[RatRibs73]

Thanks for that! Ask a simple question and you get treated like an idiot! Not what I expected. Hey ho!

Just a point though - it didn't work when I reverted back to the original circuit. That is what has completely baffled me. Didn't know if there was some diagnostic procedure I could go through to locate the fault. Before I grab the Yellow Pages....

[Ben Blaukopf]

6kA would require a fault loop impedance of 0.04 ohms which seems pretty unlikely.

Ben

[The Natural Philosopher]

With respect, to utterly fail to make contact enough on a simple job like this betrays some deep level of misunderstanding somewhere..we are merely trying to probe the extent of your knowledge to see where it fails to accord with reality ;-)

I'm

Get a meter and with the power off start checking continuity from the consumer unit all the way round the ring..short of using a HF reflectometer there is no better way to identify where the open circuits are..

[The Natural Philosopher]

It is, if its acessible.