Advice on consumer units and wiring

[robbie77]

Hello,

I have been removing a wall in my house and need advice on what to do with the existing consumer units and wiring.

hopefully from the pictures you can see the kitchen supply that is fed from another consumer unit upstairs (sorry no picture)

Would it be best to remove this extra kitchen breaker and rewire them up to the main board ( I will be buying a new consumer unit with MCB's) if so is it best to run brand new cables to the new unit or is it acceptable to crimp some of them? The assocaited wiring connects to a cooker, ring main and lights. I want the job done properly so whatever is best practice.

I am going to buy some supplies so when my qualified electrician friend comes round to help I have everything I need (I will be helping in labouring capacity)
Can someone point me in the right direction of type of consumer unit and cabling I was thinking a decent roll of 2.5m for ring mains, 6mm for the cooker and 2 and 3 core for any extra lights and switches I may fit?(I get staff discount at electrical supplies). Its a fairly large 3 bedroom Victorian detached house. I plan on adding to the existing circuits i.e outside lights and in the future power to double garage.

What do you reckon? Thanks

Untitled

• robbie77
• 20 Dec 2009
• 1

Untitled

• robbie77
• 20 Dec 2009
• 1

 

[xr4x4]

oh dear..is that a 10mm supply cable?

is that the main CU?

 

[nozspark]

You'll be better off getting your "qualified electrician friend" around to have a quick look and tell you what you need.... after all he'll be signing it off!

 

[GaryMo]

oh dear..is that a 10mm supply cable?

is that the main CU?

hopefully from the pictures you can see the kitchen supply that is fed from another consumer unit upstairs

 

[robbie77]

Thanks for the response but I was hoping for a little more information as to the consumer unit if nothing else it interests me and I like to learn.
I appreciate the danger, knowledge and competence needed to work with electricity


In principle I am assuming a new consumer unit to control all circuits is the best solution?

What are recommendations for when to crimp wires and when to replace?

 

[Spark123]

In principle I am assuming a new consumer unit to control all circuits is the best solution?

Possibly, however there is nothing wrong with a suitably designed sub main to another CU.
As unprotected T&E cables buried less than 50mm from the surface in a wall/partition require RCD protection the sub main is imho best run in a cable like SWA or similar that doesn't require RCD protection and RCD protection provided in the sub main CU.
In your case this may mean it is easier to just have a single consumer unit, speak with your electrician.

What are recommendations for when to crimp wires and when to replace?

Where practicable (cost, viability etc), best to replace.

 

[robbie77]

Thanks for your thoughts.

I think I'm going to buy a 12 mcb 2x RCD consumer unit to cover all bases!

 

[securespark]

If you get a staff discount at a wholesaler, buy a board with a 100A incomer and fit it with RCBO's. Forget the dual split board, which does not comply with the letter of the regs anyway.

 

[RF Lighting]

It might be that not all ways need to be RCD protected anyway, or your electrician might want to do away with that CU altogether.

It really is madness going out to buy bits until your electrician has been and seen the job and told you which parts he actually needs.

 

[ban-all-sheds]

Robbie - just to amplify what RF and noz have said - choosing the CU and deciding which circuits should be RCD protected and how is part of designing the installation.

And your electrician will have to sign a certificate to say that he did the design.

If you can get the CU for less than him, and he is happy for you to do that then fine, but he is the only one who can make that decision and he is the only one who can tell you what to buy.

 

[sjwkmje]

Is this another my qualified friend is going to do the work but I need to know what to buy just so we do not refer you to Part P and you are actually planning to do the work your self? Or when you come to testing the spark got abducted by aliens, moved out of the UK, insert excuse here and cannot sign it off?

Your spark is the only person who can design the installation and signs to say he has done this and can carry out the testing and inspection. Just so you know this is how I would do it:

That is a sub cu and depending on how far that is to the location of the main cu might cause some headaches if you was to pull through all new cables from the kitchen to the main cu. If the distance is like 40m or so as I have seen in some large houses to the main cu a sub main will work out better and this way the kitchen will be on its own cu.

SWA should be used to feed this cu. I cannot give you any more information on size, as this depends on earthing requirements and this depends on the supply type. Can we have a photo of the main cu and cut out? (suppliers meter, cutout and cu all in one photo would be nice)

This sub cu I would use metal clad if possible and use RCBOs on each circuit. The only make cu I recommend are Hager for an all RCBO install. SWA from the main cu to the sub cu. You could get away from RCBOs (cables need to be > 50mm depth in the walls) by using galv ducting to protect the t+e.

I am not going to do the whole design for you and the maths as your spark has to do that as he has to sign he has done the design and testing and inspection.

And as you are going to be going down to brick there is no point extending cables. Do it correctly and replace the lot.

Now second problem you said you was going to get a dual RCD board. NOW this might be wrong as we do not know the supply type (TT requires a 100mA type s and some other earthing requirements spike etc).

My advice get your spark in first ask him what he likes to work with. He might want to use all RCBOs and no sub main or remove the submain and go from here. He might dislike hager and wants to use merlin gerin etc as this is what he prefers to use. I worked with a spark who would use nothing but MK stock when I was on site labouring for him.

All this is notifiable under part P so you need to notify the BCO before work is commenced unless your spark is in a scheme and can sign it off him self. Testing and inspection has to be carried out.

Adam

 

[ban-all-sheds]

And as you are going to be going down to brick there is no point extending cables. Do it correctly and replace the lot.

I have recently bought a fairly big victorian house that is detached and rural.

and judging by the other photos is in pretty poor decorative order even where you aren't doing structural work, and is going to be having plumbing mods done as well.

There will never be a better time to do a complete rewire - don't f*rt around fiddling with this sub-CU, replace the main one with all RCBOs, or 3 or 4 separate sections, one of which just has a switch incomer, have plenty of spare ways for future expansion, cables in conduit for ease of future changes (steel conduit if you want to avoid RCD'ing the lights), priority circuits through a changeover switch so you can use a generator if you want, mains powered smoke/heat/fire detectors.....

Is your friend registered? You're going to have to involve LABC with all that you are planning, so you won't be able to slide illegal electrical work past them.