New CU and extending 13amp ring mains with mixed colours

Some info please.
My house is 1960's with 1 ring for the whole house and an old rewirable 4 way cu.
I want to split the ring to up and downstairs, this will mean new cable colours on parts of both circuits so is this allowed? The existing 7/029 t&e cable is in good condition so I really for many reasons dont want to have to do a complete rewire.
Can I join old to new colours in an accessable JB or crimp in an adaptable box to extend (with a reference to this on the cu)?

Secondly the mains in (TNS) are in the garage attached to the house and all the feeders for both power, lights & shower are fed through into the cavity via 1 missing brick and then rise to either the upstairs underfloor or the loft again via a missing brick. The cu is fitted over the hole.
Should I seal the holes once the new cu is fitted to stop it acting like a chimney if there was a cable fire? if so with what? bricking back up would make it very difficult for anyone in future to add extra circuits.

I have upgraded the earthing already with 10mm to both gas and water in, and a 16mm ready for the connection to the boards earth connection.

The existing lighting circuits were just twin, no earth. I have rewired the upstairs in t&e. Downstairs is looking a lot harder with a house full of furniture and all the existing cables buckled to joists

oldman2 said:

Some info please.
My house is 1960's with 1 ring for the whole house and an old rewirable 4 way cu.
I want to split the ring to up and downstairs, this will mean new cable colours on parts of both circuits so is this allowed?

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The existing 7/029 t&e cable is in good condition

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What readings did you get for R1+R2/fault loop and insulation resistance?

Should I seal the holes once the new cu is fitted to stop it acting like a chimney if there was a cable fire?

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It's not just cable fires you need to worry about (why should your cables catch fire anyway? How badly designed and installed are they??? ).

I'm sure that the garage is a separate fire compartment from the house, and therefore these holes must be sealed to prevent the spread of fire and smoke from the garage to the house.

if so with what?

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Some kind of intumescent filler - you'll need to do research. You can get ready-made ducts for taking cables through fire barriers but I expect they'll be expensive.

I have rewired the upstairs in t&e.

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Have you been testing and certifying the new cables?

If you're in England or Wales have you notified your local council?

Thanks for the reply, ok so mixed colours are still ok on the same curcuit as long as the notice is at the cu.

I should have said the existing ring 7/029 appears to be in good order, cliped with buckle clips to the side of joists and each acessory point is being checked as I replace the outlets.
I have an electrician who says he is willing to come do a test on the whole house once I finish.

Something like fire cement and brick to fill the holes then, I will look further into this. I dont really expect any cables to catch fire but then nobody expects a fire of any sort, I just want to remove any obvious paths.

I use fire-rated expanding foam for filling big holes

oldman2 said:

each acessory point is being checked as I replace the outlets.

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Checked how? Just visually?

I have an electrician who says he is willing to come do a test on the whole house once I finish.

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You do realise that in England and Wales that is not how you comply with the law?

Something like fire cement and brick to fill the holes then, I will look further into this. I dont really expect any cables to catch fire but then nobody expects a fire of any sort, I just want to remove any obvious paths.

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It's the path from garage to house that you have to close off, i.e. both ends need to be sealed.