CU tidy up

[Steve]

Since my CU was fitted in 2006, I've been meaning to tidy it up, because the guy who fitted it made such an abortion of it. I have a week off next week, and plan to tackle this then. Planning is everything, I dont want to leave us without power for too long!

This is what I have right now:

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• Steve
• 30 Jan 2010
• 1

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• Steve
• 30 Jan 2010
• 1

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• Steve
• 30 Jan 2010
• 1

and without all the junk:

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• Steve
• 30 Jan 2010
• 1

Most circuit cables enter the CU from above.

Jobs:

Fit a piece of chipboard, covering all the rough plasterwork on the wall the CU is on.
Renew tails from meter, in one run to the CU.
Fit empty plastic box between the CU and the ceiling.
Refit CU under plastic box.
Extend all circuits via crimps, into the CU.
Use plastic trunking across the bottom of the CU and meter board for the earth bonds and cable exits.
Re-terminate the SWA, which currently just sits inside the bottom of the CU. I have a gland for this (which I left on view for the spark doing the CU change)

Basically, if folded flat, I want to end up with this:

Several queries though.

Do I run the earths up around the CU/box or through them? I know I can use the earth bar in the CU as the MET, would this be a better solution, given the layout?

Can I terminate SWA onto plastic trunking, or will I need another box under the trunking for this? (I have a spare metal box in the shed, I'll probably end up using this anyway, because im guessing that even if allowed, doing it onto plastic will be hard!)

Any tips on using crimps and ratchet crimpers?

Do I need to 17th edition (RCBO) everything, due to extending every circuit?

Anothing thing, during the change, I will need power to drill the wall (I have a cordless but its crap at hammer, be there all day with it). I could also do with power for a light (this is high up under the stairs, no natural light). Would it be wise to temp in a cheap garage CU and double socket for the duration of the work (on ebay, and flog it again after). This way my dad might be able to watch his footy too.

Theres a 10mm cable in the CU for the shower, but the crimper I want only goes up to 6mm. Is there a way? Or do I have to plump for the 10mm crimper?
Are insulated crimps ok as they are, or is it wise to heatshrink them too?

On my shopping list I have:

-butt crimps (20x1.5mm, 20x2.5mm, 10x4-6mm)
-crimper
-240 x 190 x 90mm IP56 Moulded Box
-flat cable glands x10 (for visible cable entries - will just cut a hole in the top of the box against the ceiling for others)

Will buy trunking and board and fixings from B&Q.

I would update the CU to 17th edition, dual RCD etc, but the budget wont stretch that far unfortunately.

Any advice welcome.

Steve.

 

[RB2004]

Hi, just a word of warning.. but its quite likely this work would come under Part P.. because it sounds like you will be essentially re-wiring the consumer unit, also when doing this scale of job.. you would normally ensure the circuits are brought up to date... if you are adement to do this job at your own risk and in the knowledge of part P.. if you are disconnecting everything and re-wiring it would be wise to upgrade to 17th edition board as it offers better protection due to everything being RCD protected, and redundancy because upstairs and downstairs are on separate RCDS.. or some electricians do front and back of the house on new builds.

RCBO'ing everything will cost far more than a 17th edition board with 2 RCDs.. being in mind MCBs are only a few quid each.. RCDs are probably most expensive part but still cheaper than RCBOs

bearing in mind you will need to RCBO anything which isnt RCD protected with wiring buried less than 50mm within the wall, and not sufficiently mechanically protected

Also when crimping.. only use a rachet crimper to get a good connection, then remember to heatshrink afterwards preferably. When crimping a good connection is essential, because if the connection isnt good enough the join will become high resistance and heat will be generated that can further lead to the possibility of a fire.

SWA would be terminated into a separate termination box which joins onto the T&E which then goes into the CU... if you use a metal box, remember to earth bond it, neater this way and gives more flexibility when wiring into the consumer unit.

Also rather than B&Q, if you have a branch local, I sugest you use "http://www.screwfix.com"

they do have branches with counters where you can walk in and pick stuff up.. so if theres one near you it would be better to go there... reason being although they are part of the same company as B&Q they are alot cheaper.

another good company is, http://www.tlc-direct.co.uk again they also have trade counters.. but shop around because sometimes screwfix is cheaper, and other times TLC is.. TLC wanted around £55 for an RCD a while back.. and screwfix only wanted £35 so worth shopping around.. for reference both of those RCDs were identical make and ratings.. so I dont know why there was such a steep price difference.

Certainly both places will be alot cheaper than B&Q for the crimps.. so dont buy them from B&Q

 

[ban-all-sheds]

1) Why not use galvanised trunking if you wan to be able to terminate SWA in it? Get yourself a 20mm punch (e.g. Q-Max) - makes nice neat holes in next to no time.

2) If you're lowering the CU, why not lower it enough to avoid the dog-leg in the trunking?

3) Get a blank for that empty CU position.

4) How do you propose to isolate the installation?

5) You're going to be extending cables. For your own safety, if nothing else, you should check that you've done it properly by testing - continuity values (i.e. R1,R1,Rn) and insulation resistance.

 

[fattony]

BAS I've never seen a Q- Max until I googled it just now, what advantages do these have over a holesaw? From what I just saw they look more expensive?

 

[martinxxxxxx]

Hi Steve.

While it is a noble ambition to have this all nice and tidy, there maybe more to than meets the eye. As if that is not enough as it is.

In the picture with the service head on it looks like there are electricity board seals on all of their boxes - what do you propose to do about breaking them?

Also I would be nervous if I were you about doing all of this work without testing the whole installation first, a days work if you have done it before. Maybe more, if not. You will need to hire a tester (assuming you don't own one) to do this and follow the test and inspection routine in Guidance Note 3. If you don't do this you leave yourself open to a lot of problems further down the road of your project.

I don't think it is worth doing unless you are updating the CU. In fact i think by the time you have done the extending of the cables you will have crossed the threshold of being compelled to update the cu, by virtue of the fact that you have affected the wiring of every circuit in the installation. So your old cu would not be compliant. So I think the budget is going to have to be stretched.

I am not going to part p you to death, but guess you are aware of part p aren't you? Also is notification to BCO in your budget ?(£100-300 depending where you live) unless you are a member of a competent person scheme which you may be?

As for crimpers these guy sell 10mm ones click
Crimpers

Just go in to this with both eyes open is what I am saying

Martin


ps fattony Q-max are wonderful - no swarf when you need a new hole in an existing panel for one good reason basic cheap one

 

[electronicsuk]

Do I run the earths up around the CU/box or through them? I know I can use the earth bar in the CU as the MET, would this be a better solution, given the layout?

Running through will look neater, there's nothing wrong with doing it either, although do try to bend the cable such that it stays well away from any exposed live parts. It shouldn't be particularly difficult to form 10/16mm in this way. A separate MET is equally accessible, and some might argue better as it makes it easier to check the integrity of PEBs without removing the CU cover, although it wont look as neat.

Can I terminate SWA onto plastic trunking, or will I need another box under the trunking for this? (I have a spare metal box in the shed, I'll probably end up using this anyway, because im guessing that even if allowed, doing it onto plastic will be hard!)

Although there isn't a regulation prohibiting it in specific terms, it doesn't sound like a very good idea to terminate onto plastic trunking. As per BAS's suggestion, use metal trunking or stick to your original idea of a metal adaptable box. I'm not completely against glanding straight into a plastic CU for small sizes of SWA where the enclosure is sound and an earth nut is used, although with your trunking layout I think this would be impossible anyway.

Any tips on using crimps and ratchet crimpers?

Use the correct size crimps for live/neutral conductors and CPC. Give the joint a tug afterwards to make sure it's sound?

Do I need to 17th edition (RCBO) everything, due to extending every circuit?

I'd say no, as in essence all you're doing is extending existing circuits. As the additional cable you're adding will all be surface mount in trunking, there is no requirement for the new portion of the installation to be RCD protected, at least in terms of burial depth etc. That isn't to say that it wouldn't be a good idea, though.

Anothing thing, during the change, I will need power to drill the wall (I have a cordless but its crap at hammer, be there all day with it). I could also do with power for a light (this is high up under the stairs, no natural light). Would it be wise to temp in a cheap garage CU and double socket for the duration of the work (on ebay, and flog it again after). This way my dad might be able to watch his footy too.

Ahem. I've seen a friend's brother's cousin, twice removed, just fit a 13A socket straight to the tails (with a few strands of copper cut away) where such a temporary supply is required for a few hours. Not that I would openly condone my friend's brother's cousin twice removed actions on a public forum.

Theres a 10mm cable in the CU for the shower, but the crimper I want only goes up to 6mm. Is there a way? Or do I have to plump for the 10mm crimper?

I think you already know the correct answer to that question. There's nothing to drop you using screw terminals in an enclosure, but if you wanted to go about it that way (which IMO is a bit of a botch unless you do it neatly with DIN rail mount terminals) then you wouldn't be asking about crimping in the first place.

Are insulated crimps ok as they are, or is it wise to heatshrink them too?

In enclosure/trunking, they are fine as is, just make sure there is no exposed conductor showing.

 

[electronicsuk]

I don't think it is worth doing unless you are updating the CU. In fact i think by the time you have done the extending of the cables you will have crossed the threshold of being compelled to update the cu, by virtue of the fact that you have affected the wiring of every circuit in the installation. So your old cu would not be compliant. So I think the budget is going to have to be stretched.

No matter what the NICEIC would have you think, you certainly are not compelled to bring an entire circuit to current standards just because you've added to part it. Only the additions need be compliant - often this simply means additional RCD protection. This may well best be achieved by replacing the CU or adding RCBOs, but it isn't the only option available. In Steve's case, the extra wiring will not require RCD protection other than that required for socket outlets, as it will be surface mounted.

 

[ban-all-sheds]

BAS I've never seen a Q- Max until I googled it just now, what advantages do these have over a holesaw? From what I just saw they look more expensive?

They are more expensive, for good reason, and worth every penny.

All I can suggest is that you get a scrap bit of steel sheet, drill a 20mm hole with a holesaw, and then compare your hole with the K/O ones in galvanised boxes.

 

[ban-all-sheds]

basic cheap one

You have an odd idea of what constitutes "cheap"

http://www.rapidonline.com/sku/Tool...ts/Circular-sheet-metal-punches/34566/86-5310

 

[ban-all-sheds]

My view on the testing/17th compliance. Other views are available.

If you aren't installing circuits, then you are not responsible for their state of compliance with the 17th.

You are adding cabling to them, so you should make sure that their safety is not compromised by your work, which means verifying that their continuity is OK, their R1+R2 is OK and their insulation resistance is OK.

If you're adding RCDs/RCBOs then you should test those too.

Having got that far you might as well test your fault-loop impedances as well.

 

[martinxxxxxx]

No matter what the NICEIC would have you think, you certainly are not compelled to bring an entire circuit to current standards just because you've added to part it.
.

I agree.

However the work being done will need an EIC (not a MWC) by virtue that every circuit is being changed. The person doing the work will have to sign it off for every circuit and the date of installation will be the new cert date. Therefore I am compelled to believe that it should be done in accordance with the latest editions. The original installer could quite legit say that after the new work is done it is no longer her install.

I would not take this job on without pre testing and being the install up to current regs, otherwise what is the point of all the work.Another £80 for a cu would be worth it, surely?

Martin

 

[Steve]

4) How do you propose to isolate the installation?

I'm gonna wait for a power cut and take my chances with some rubber gloves.



Although there are seals present on the main fuse, they aren't intact. And I am aware I'd have to cut the seal on the meter, but I'll make it look intact after myself. Bit of Araldite should do the job.

Ban, good point on moving the CU down further. The wall is unused anyway.

I figure by re-instating the original CU I'm not making it any worse. I am aware there is also an earth fault on the upstairs ring final, so I dont want to RCD everything on the day, though I may make an ongoing job to replace the MCBs. We are planning some "knocking about" of the house this year, so electrics will be updated.

I have a blank for the empty slot, one of those "been meaning to do it" jobs.

I will use a metal box under the trunking for the SWA to attach to.

One of the regulars on this forum posted a photo once, of him working on a CU change, with a single socket hanging off the meter. I wont be doing this.

The electrician who fitted the CU didn't test every circuit, in fact one circuit he connected to the RCD kept tripping it, and he opted to put it on the non-RCD side eventually.

I'm in two minds now. Though one forum regular has offered his services in return for beer money, he would have to travel about 40 miles.

 

[electronicsuk]

I'm in two minds now. Though one forum regular has offered his services in return for beer money, he would have to travel about 40 miles.

And you're turning him down?!

 

[Steve]

I'm in two minds now. Though one forum regular has offered his services in return for beer money, he would have to travel about 40 miles.

And you're turning him down?!

No. We have just been making arrangements actually! You may know him. He lives near you.

 

[electronicsuk]

I'm in two minds now. Though one forum regular has offered his services in return for beer money, he would have to travel about 40 miles.

And you're turning him down?!

No. We have just been making arrangements actually! You may know him. He lives near you.

I figured as much. He still owes me for a job I lent a hand with a few weeks ago, hint hint if he's listening