Replacing consumer unit - need junction box (SCOTLAND)

[iep]

I'd like to replace my old fuse box with a modern RCD consumer unit (that I already have). The problem I have is that the existing wiring is going to be a little too short for the new consumer unit as it is quite a lot smaller than the old (massive) fuse box.

Is there any sort of simple junction box that can be used to extend the existing wiring? I've seen a few 6 way 15A boxes but I'd need a 30 way box to accomodate all the wiring and it would have to be capable of carrying 40A (for the cooker circuit).

Cheers,

iep

 

[MalcofArabia]

pjd1.jpg Terminal_Block_2way_AKZ4_Klippon


ADR3575‑S7874.jpg

Best way to do it or you can crimp each cable.


You realise that all this work will need a EIC and so will be eother notafiable to the Local Building Control or done by an Electrician in a recognised scheme

 

[MalcofArabia]

better link




http://www.iboco.com/Products/DinRail/DinRail.html

http://cnflin.en.alibaba.com/product/237358588-200492485/Terminal_Block_2way_AKZ4_Klippon.html

http://www.brenclosures.com.au/pj.htm

 

[iep]

The whole local building control EIC query remains a bit unclear to me.

In Scotland the rules seem to say that this rule applies only to those electrical jobs that are part of larger work that requires a building warrant (building an extension etc):

http://www.esc.org.uk/safety-in-the-home/electrical-safety-laws.html#scotland

I'm pretty sure I don't need a buildin warrant to change a consumer unit provided I am not adding any extra circuits or changing the existing ones?

Either way, many thanks for the links.

iep

 

[iep]

Since I own a 1 storey house, it looks like I don't need a warrant and so (I think) don't need any certification:

http://www.scotland.gov.uk/Resource/Doc/217736/0098173.pdf

iep

 

[ban-all-sheds]

I'd like to replace my old fuse box with a modern RCD consumer unit (that I already have).

Replacing a CU is not just like replacing a plug but with more connections to make.

You cannot assume that everything about the existing one is OK, or that all of the existing wiring is OK, and that you can just swap the CU over and end up with an installation which complies with the wiring regulations, or even works or is safe, and yet you'll be taking responsibility for the working and the safety.

• For a circuit to supply a load (doesn't matter what), how would you go about deciding what cable and protective device to use? You must not assume you can just copy what's there.
  
  
• 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 cables are installed 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?
  
  
• 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?
  
  
• What will your RCD/RCBO arrangements be with respect to 314.1?
  
  
• How do you propose to isolate your supply so that you can connect up your new CU?
  
  
• 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?
  
  What testing will you carry out before you start the replacement?

 

[JohnD]

It would be much more usual to extend each cable by a permanent crimp connector.

You can get crimps with their own heat-shrink sleeving which is excellent

You also need to enclose or sleeve overall to provide something equivalent to the original sheathing. Min-duct is quite neat. Transparent sleeving enables people to see what you have done.

A tip: If crimping, the extra bulk can be a nuisance, so stagger the three crimps in each T&E so they are not next to each other

You have to use a proper ratchet crimper, not a Silverline or unbranded one as they are usually rubbish. It will cost you on the region of £30. The common ones will usually do cables from 1mm to 6mm in their three jaws, but not 10mm or 16mm which you may have for an electric cooker or shower. The bigger crimpers are quite expensive you might be able to hire one if you need it. Practice your joints first as you might get some faulty or loose ones.

 

[MalcofArabia]

It is though recommended in the BS 7671 and most of the recognised agencies ie Niceic, Napit etc that a consumer unit change requires an Electrical Installation Certificate Schedule of Inspection and a schedule of results that is anywhere in the UK.

I'm not fully conversant with Scotland, though the 1 story house clause is interesting. What is the difference apart from size from a 1 and 2 story in the context of electrical safety?

So even if it's not notafiable as you seem to think when you go to sell or maybe claim on an insurance, it will be recognised you have what is called a 17th Edition CU and they may want to see the certification for it.

 

[ban-all-sheds]

What is the difference apart from size from a 1 and 2 story in the context of electrical safety?

Would it be a similar difference to the one which makes adding a socket in a kitchen more dangerous than adding one in a utility room?

 

[MalcofArabia]

Thought you would have known that the electricary in a kitchen is more dangerous than in a utility room

 

[iep]

Thanks to all who have replied (I'll be sure to be especially careful of that extra dangerous kitchen electricity). I'll also lok into the crimping solution as it seems neat and safe.

In response to ban-all-sheds, I am familiar with the wiring of the house and have double checked at that all circuits have been wired in the correct gauge of cable and that there are no runs of bundled cables. We have two 32A ring mains and neither have been spurred off. It's a small house so no requrement for more than that. The garage and bathroom (shaver socket) have ther own 16A non-ring mains.

All ring mains will be on their own MCB and these will be provided via the RCD of the split load CU. Lighting circuits will be run from 6A MCBs.

Fortunately, my system includes an isolation switch so I can fully shut off all power to the CU during fitting.

I am not moving any of the existing wiring. Just extending the last 10cm to make for easier fitting to the CU. So, do not plan to look into the regs for routing of wiring.

FYI, the only time that a building warrant is required for wiring within a 2 storey or less house is if a CU or recessed scoket is to be installed on a shared wall. Ours is a detached house so that rule would not apply.

Cheers,

iep

 

[ban-all-sheds]

In response to ban-all-sheds, I am familiar with the wiring of the house and have double checked at that all circuits have been wired in the correct gauge of cable and that there are no runs of bundled cables. We have two 32A ring mains and neither have been spurred off. It's a small house so no requrement for more than that. The garage and bathroom (shaver socket) have ther own 16A non-ring mains.

And you're happy that all of the installation methods are OK?

You have tested, or will test, for continuity, particularly of ring final conductors, and you'll measure Ze & Zs?

All ring mains will be on their own MCB and these will be provided via the RCD of the split load CU. Lighting circuits will be run from 6A MCBs.

You say "the RCD of the split load" - that implies only 1?

Nit sure how that makes it a "modern" CU.

Also, is your plan to put MCBs on the non-RCD side?

I am not moving any of the existing wiring. Just extending the last 10cm to make for easier fitting to the CU. So, do not plan to look into the regs for routing of wiring.

So you're just going to assume that it's all OK?

FYI, the only time that a building warrant is required for wiring within a 2 storey or less house is if a CU or recessed scoket is to be installed on a shared wall. Ours is a detached house so that rule would not apply.

Building Warrants are one thing.

Electrical Installation Certificates are another. How will you get one of those?

 

[iep]

I have one of these units populated with the appropriate sizes of MCB:

http://www.screwfix.com/prods/60251...-Way-Fully-Insulated-Split-Load-Consumer-Unit

All seperate circuits will have their own MCB and 6 of the MCBs will be fed from the on-board RCD. I may remove the single RCD and replace all MCBs with RCBOs later on.

Without wishing to be rude, I am dubious as to the requirements for a full review of the existing wiring and installation methods within the house.

Given that the CU I am using will replace all the fuses with like for like MCBs, there will not be any change in the operating conditions for the existing wiring under fault or non-fault conditions so I think I am happy to go ahead.

After all, if I were not about to be replacing the consumer unit, would you still recommend I carry out all the tests that you describe? In that case, are you recommend some form of periodc check?

However, if I am missing something, I would be keen ot hear your thoughts.

As for the electrical installation certificate, I am yet to find any piece of legislation that states that I require one. That is not to say that I won't have it checked by a certified electricion later on but I'm still curious as to whether this is actually necessary.

Cheers,

iep

 

[iep]

Just looked up ring final, ze and zs testing. Yes, I'll be doing those. Especially the ring final testing as it is very easy and very useful.

Good tip, thanks,

iep

 

[rebuke]

All seperate circuits will have their own MCB and 6 of the MCBs will be fed from the on-board RCD. I may remove the single RCD and replace all MCBs with RCBOs later on.

I assume then that none of the circuits that won't be protected by the RCD are buried at less than 50mm in a wall (i.e. are all in earthed metal conduit, or SWA/pyro or similar cable), and aren't feeding any general purpose sockets etc etc?