Newly fitted consumer unit query -

How many rings are there? You use one MCB per ring. Assuming they are rings, of course.

What on earth is connected to it? A 6 amp one will do for any alarm I've ever seen.

I'd read up a bit before attempting any such thing.

The two ends of a ring ought most definitely to run to the same MCB. But are you really really *really* sure they're two ends of one ring, and not separate radials? Who was this "fitter" - knowlededgeable, experienced, or someone you met in a pub who said they could do the job cheap cash-in-hand-like?

The alarm system takes a tiny current. If it's fed off a circuit with a

It's almost an "if you need to ask you shouldn't be doing it" question... With the right training, gear, and a mate standing by, live working is a perfectly reasonable answer (how do you know the fitter wouldn't have done it this way? Sounds like you weren't there...) Most common approach is to pull the main supply fuse, do the work, replace it, and if very consciencious, tell the bored and clueless call-centre operative at your electricity supply company that it needs resealing. (And listen to the answer "Sorry, I don't seem to have a category for that on our screen, but can I interest you in our dual-fual offer with 20% extra discount on car breakdown service?"). Further in the "shouldn't need saying" deparment, you do that with the CU switched

From the questions you ask, you may be a lot better off paying a local electrician 40-60 quid for an inspection of chummy's "work" and the whole of your wiring; at the very least, find a good book on 'lectrics at the library and work on understanding it deeply...

HTH - Stefek

I must admit i got a pal of a mate to change the unit. He did it for £20 - must explain the mishaps. I have checked and i only have one ring circuit in the house. All sockets work with either of the 2 MCBs switched on and don't work when both are switched off, so i need to change the 2 MCBs into 1 ring circuit and remove the spare MCB.

With regards to the alarm, the wire from the consumer unit goes directly into the power backup type station of the house alarm. Many people suggest 16A is too high for what is effectively power to a battery and suggestions appear for it to be replaced with a 6a MCB - Is this something i should do.

With regards to isolating the power, is the main 100a fuse in a squarish type black box of approx 3"?

Ouch!

I'd really want to check (or get someone to) the whole CU installation.

I guess this is why Part P of the Building Regs is coming into force. I know someone who wired a 9.6kw shower to the douple-pole isolating switch with *flex*.

Better get on with my rewiring before January...

Al

I suspect that you *have* got two rings - but that they are crossed over in the Consumer Unit. If this is the case, they will both work with only 1 MCB on - but neither will actually be a ring under these conditions. Sounds like you should have paid a bit more for someone who knows what he's doing! What's your mate's pal's day job - brain surgeon?

In any event, it needs sorting PDQ!

It might be OK if the flex was thick enough.

What's this please and where can I see these regs?

Thanks,

Steve

If you have two rings that are crossed over then surely you just have one big ring with either MCB on (probably not a big problem as long as you dont break the 100m^2 (?) floor area it covers). But if you have both MCBs on then the whole circuit is protected by the sum of the 2 MCBs (64A) which I guess is very bad - as well as the fact you cant isolate just one ring.

I think it is just one ring... Found the 100a supply isolator and pulled the fuse, opened up the CU and removed a 32A MCB, transferred the live wire from the top to the adjoining 32a MCB to create my ring. It must be a single ring as i only have 6 double and 1 single socket in the whole house. Also changed the alarm mcb from a 16a to 6a, put the cover back on, inserted the fuse and hey on it came and appears fine.

I did install one of the double sockets myself by taking a feed from the back of another socket which already was part of a ring. Would taking the feed directly from the socket (ie 1 line in and 2 out) pose a problem as i didn't wire up a junction box.

With regards to my friend's pal's day job, he works in mail order company. Studied electrics at college but failed his exams. Said he knew what he was doing, but i have checked his installation with the installation guide that came with the unit and it appears correct.

Google: "Part P" "building regulations"

Yeah. Better. Problem with wiring is that "it works" tells you there's a live feed getting to the load, and that there's a return path (possibly not all down the neutral conductor of the same circuit). That's some way off "it works and is safe". To take the grossest example, everything will still "work" if every single earth conductor is disconnected in the CU (no, DON'T do this!). It's only if there's then a fault that you could tell the difference (with earths that work: MCB trips. Without: someone gets a shock, possibly fatally).

No problem with that arrangement: taking an unfused spur off the back of a socket on the ring is normal practice, and is marginally better than using a junction box in minimising the number of connections. Hope you've done all the good practice things: sleeved the earth wires, made sure all 3 conductors are in good contact in their respective terminals, folded the conductors back neatly into the backbox so they're not under unnecessary strain, fitted the rubber grommets to the backbox so the cables aren't going to be najjered over time by the sharp edges of the knockout, etc etc.

There's "courageous", and "loyal"; and then there's just plain daft. If he failed his exams (they're multiple-choice, the passmark is said to be around 45%, and most courses will coach and allow retakes), this should tell you something about his state of knowledge; yes, some people don't get on with exams - but the dismal impression of his knowledge is confirmed by the two serious faults you've found already (ring wired so wrongly that the MCBs wouldn't pop even if you drew 80A from all those sockets, by which time the cable temperature would've risen to, oh, 200 degrees C, melted through the PVC insulation, yada yada); and the alarm panel wired to a 16A MCB where its incoming cable needed a lower-rated MCB. The CU installation guide is *not* a "this is how to do electrics" all-in-one course - the CU manufacturer assumes, as they're entitled to, that the CU is being fitted by someone competent.

What other cockups are lying in wait for you? Tell me all the earth conductors in the cables feeding the CU are correctly connected into the CU's earthing bar. Tell me he didn't need to make any of the cables a bit longer to reach the new MCBs, and has used a 20A lighting junction box to extend your cooker feed. Tell me he's experienced and knowledgeable enough to assess the state of the existing wiring.

Tell me your safety - and that of anyone else living in your place or visiting - isn't worth the 60-80 quid it'll cost you to get a local electrician to do an inspection on your installation; those inspection visits (if you make them a cuppa, be friendly, and the like) will give you plenty of information about the state of your electrics, and will quite clearly separate the "imminent danger" items from the "would be nice" ones. If any of the cockups are a matter of moments to fix, you may get them done on the spot as part of the same visit.

Do it today/tomorrow. Really. I'm no defender of the excesses of the health-n-safety brigade, but everything you've said about your installation rings alarm bells in my head.

I'm afraid that sounds to me like the blind leading the blind.

The installation instructions assume a knowledge of the basics.

Sadly lacking in both your cases, unfortunately.

Do you think it would have made a scrap of difference in this case?

None whatsoever. I didn't say it would solve the problem.

That's the problem with Part P. It doesn't solve the problem which it is intended to solve. It seems likely that it will actually create new problems. It certainly won't make any difference in situations like these.

Al

Yes, you're right of course! I was thinking in terms of two radial circuits, forgetting that they were connected together in the "OFF" MCB.

Believe it or not Stefek, he did not touch the cooker unit, but he did pop out to his car to get some black wire - Meaning he must have extended a neutral wire as it did not reach the neutral block.

With regards to earth, i have an earth block in my cu which every entry wire into the cu is connected to. This earth then leaves the cu and into a junction box. 2 wires then leave this junction box and onto 2 separate locations around copper pipes. Should the earth wires be leaving the building as part of the electricity company wires, as they are only currently going to 2 copper pipes in my cellar.

I take it that the "junction box" outside the CU is a big zinc-plated block, uninsulated, right? This is your main earthing block. And you're saying it has one (let's assume quite thick - better had be) green-and-yellow from the CU's earth busbar to that; and two green-and-yellows going to (at a guess) water and gas pipes in the cellar. In which case, you're right to worry about where the "real" or system earth is coming from; 30+ years ago it was still considered adequate to believe in using a watermain as a house earth, but now that plastic pipe is widely used - and your existing lead-or-copper one could be replaced with a plastic one in the event of a leak - it's not been acceptable for quite a while. (In non-rural locations, it's quite common for the electricity company to be able to provide an earth for you: but there's no obligation on them to do so.)

Look - none of us can offer you authoritative advice/diagnosis over the Net. There's enough ungoodness in the wiring you describe that you really, really do need to get a real honest-to-goodness practicing electrician in to give it the once-over. They'll tell you what needs doing, and there's no obligation to get them to do all that work - they'll identify anything really dodgy separately from the merely nice-to-dos, and you might well be able to do some or most of any fixing that needs doing yourself if cost is a major issue. (The bulk of a bill for an electrician doing domestic work tends to be for chopping out routes for cables to run: if you can do this for them ahead of time, you can get them to do the electrics-specific work only - if you find the right kind of outfit, obviously...)

HTH - Stefek