How does my DIY effort at a consumer unit look?

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f0rmula said:
I'd be hugely interested to see how you get on :) I'm about to start my own re-wire in the summer, but it's a re-wire from scratch, so I'm hoping it might be a little easier than patching an existing installation.
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  • For a circuit to supply a given load, how would you go about deciding what cable and protective device to use?

  • Do you know which circuits can be ring finals and which cannot, and what the advantages and disadvantages of each are?

  • Do you know what the two main lighting circuit topologies are, and what the advantages and disadvantages of each are?

  • How do you calculate maximum demand and how can diversity be used?

  • What are the 3 different types of domestic single-phase supplies provided in this country, how would you recognise them, and what differences do each make to the requirements for the rest of the installation, particularly any outdoor supplies?

  • Can you correctly identify all components and connections of a circuit by method of testing or otherwise? In doing so can you identify or recognise anything wrong or dangerous with the circuit?

  • Do you understand how the way in which you install cables affects how much current they can carry?

  • What are the rules concerning cables concealed in walls, partitions and under floors?

  • What are the rules for cables run outdoors, buried in the ground or overhead?

  • Where cables need to be joined, how should this be done / not be done and in what circumstances are different methods acceptable?

  • Can you identify extraneous conductive parts, and do you know the requirements for main and supplementary bonding of them?

  • Which circuits should be RCD protected?

  • How do you propose to isolate your supply so that you can connect up your new CU?

  • LABC will not do proper testing for you, and will not give you an EIC. You have to take responsibility for testing, particularly before you energise.
    Do you know what tests you would carry out on the installation - what sequence you'd do them in and at what point you would energise the installation, and for each test do you know what is being measured, why it is important, how you would carry out the test, and with what equipment, and what sort of results you would expect to get if everything was OK?

The thing is, rewiring a house, installing new CUs, possibly outside supplies, submains etc is not a trivial job, and I can assure you that it involves knowing far more than you think it does.

Asking questions here can be a useful part of a learning process, but they are not a substitute for proper structured studying. The key term there is "learning process" - you cannot learn all the things you need to know just by asking questions here. It isn't structured enough - it won't provide you with a way to progress where each step builds on what you learned before.

You can't carry out a job of this magnitude by asking whatever random questions happen to occur to you. What if you get something wrong because you have no idea your knowledge is wrong? What if you miss something because you simply have no idea it even exists, and just don't realise you don't know it?

Summer is only a few months away, and you haven't even got a copy of the Wiring Regulations yet - you've got a steep learning curve ahead of you.
 
As a DIY attempt it's quite good to be honest. Have seen some awful attempts in the past.

However, there are a few, fairly minor, things wrong. Sorry if I repeat anything that's been mentioned.

Can only see four white functional leads on RCBOs, perhaps one is hidden.

Neutrals and perhaps earths in incorrect sequence.

Would have liked to have seen earth tag (banjo) on SWA gland.

Would have liked to have seen the larger amperage breakers and RCBOs next to the main switch.

As regards to it being 'messy' I would say it's neat enough, certainly compared to some installs.

Often if you have a dedicated circuit you don't want to trip, with it being on it's own RCBO greats reduces the chances of tripping compared to it sharing an RCCB with other circuits. Certainly wouldn't want to chase 50 mm or so deep, unless cables in some sort of suitable void or cavity.
 
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sparkiemike said:
It is a bit messy.

You appear to have forgotton to apply the numbering sticker for neutral and earth terminals - its probably still in the box.

Normal convention for the MK consumer unit would be to have the main earthing conductor and bonding on the very right

So your neutrals and earthing conductors are difficult to identify which circuits they belong to see reg 514.3.1 - if I had to test that I would be annoyed!

So are you saying your chases are greather than 50mm? Hope they comply with building regs and are not too deep. Vertical chases max one third of wall thickness, horizontal one-sixth of wall thickness.
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Thanks, I'll label it properly before the inspector comes. I took care to attach them in sequence.

As for my 50mm chases, I have the floor up so virtually the whole run is through floor voids. There's a bit in the stud wall where the CU is, which is just over 50mm including an inch of plasterboard on each side. Then there will be short vertical chases up to each socket. The plaster on my external walls is also over 40mm deep in most places - do the permitted chase proportions include plaster?

Thanks.
 
sparkiemike said:
The supply cable looks like a some 3core SWA (10mm or 16mm) in old colours

I would be interesting to see how the gland is made off.
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The incoming was three 25sqmm in an armoured sleeve, which seemed a bit overkill for a small domestic installation. It came from a TN system, which I was able to isolate at another communal distribution board, to install the new CU. I reused the thing from the old CU to anchor the incoming armoured cable to the new CU; it attached bit like an old co-ax TV aerial termination.

The CU itself earths through a lobe into the very end (right hand side) earth terminal.

The incoming tails were old colours: red for live, blue for neutral and plain yellow for earth. All bend round to the left and then up; I sleeved the end of earth in yellow and green which takes up the first three sockets of the earth strip, but the lower part is still pure yellow. The yellow and green on the right hand side is just a bonding cable that I've reused from an old installation.

I paid for BC electrical certification, the extra fee of about 300 quid and have agreed that will include four inspections - first and second fix for each side of the flat (done separately as I'm living here while I'm doing it). They should be able to inspect first fix fully if they want to as the floor is still mostly up and ceilings down.

Thanks for all the comments.
 
rcd1976 said:
It's a standard 2.5sqm T&E ring - rated over 20A. That should allow me to have an oven up to about 4.5kW, no? There is nothing else on this ring.
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That's alright then, I just thought they looked smaller (than 2.5) and wondered why two on oven circuit.

In fact, larger than 4.5kW with diversity.
 
A ring circuit for one appliance, on a 20amp MCB? So essentially two cables in parallel? Did it not occur you should perhaps just install a single larger cable.

You should be glad the supply cable is armoured SWA, otherwise you would have issues RCD protecting it in the wall.

You would be better using short stabs of galv conduit bushed correctly into the metal boxes on the non RCD protected 'short chases' to the sockets.

Let's have some photos of everything else then.......inc gas and water bonds, oven isolator, prepped chases etc....
 
f0rmula said:
rcd1976 said:
Any howlers before I let building control do their worst...?
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I'd be hugely interested to see how you get on :) I'm about to start my own re-wire in the summer, but it's a re-wire from scratch, so I'm hoping it might be a little easier than patching an existing installation.

Is this the 17th edition you mentioned?

http://www.amazon.co.uk/17th-IEE-Wiring-Regulations-Installations/dp/0750687215

Thanks for any replies.

Cheers,

James
Click to expand...

James,

Yes, that's the standard wiring regulations. For DIYers it's not all you'll need though as it mainly tells you what you can't do, rather than actually how to wire anything.

From my experience, I'd say ripping all the old cabling out and starting again was much easier than trying to work out exactly what is going on with an existing installation and then modify it. But you need good access to voids to do this.

I'll let you know what BC (or their electrician subcontractors) make of it...
 
EFLImpudence said:
rcd1976 said:
It's a standard 2.5sqm T&E ring - rated over 20A. That should allow me to have an oven up to about 4.5kW, no? There is nothing else on this ring.
Click to expand...
That's alright then, I just thought they looked smaller (than 2.5) and wondered why two on oven circuit.

In fact, larger than 4.5kW with diversity.
Click to expand...

No it's not alright.

BS 7671 only recognises ring final circuits on a 30A or 32A OCPD

The circuit you have is a none standard circuit. You will need to show all your design calculations to the inspector to prove it is compliant with BS 7671, not to mention it's a horrible way of supplying a single appliance.
 
D

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