Mix of T&E wires for ring mains

[Smellypunks]

My house seems to have a mix of 4mm cable for the ring mains. It is a 1930's house but I am thinking the electrics are maybe 1970's/80's?

Now last week I switch a single to double socket downstairs and the T&E looked like (4mm?) Copper Clad (I am no expert but it was stranded and silver looking.) Only one photo showing the socket and the copper clad earth (note ignore the copper used to ground the backbox that was new).

Now I am upstairs and again have (4mm?) T&E BUT it is (4mm?) stranded copper. Two photos of this showing the copper and the cable size compared to 2.5mm T&E.

So I am looking to extend the ring main in the bedroom and have 2.5mm T&E solid core, Wago 222's and Wago 41A Junction Box. Now my question is am I ok with the 2.5mm T&E?

I should say that I am unsure if the full ring is copper or maybe mix of more of the copper clad 4mm. There is nothing written on the old cable not like the new stuff.

Both rings are on 32A MCBs.

It is my understanding that with copper clad regs required 4mm on a ring. But with up stairs if it is copper which is looks like then why did they use 4mm? Not that is matters, what really matters is what I should do next.

thanks
C

 

[Jurassicspark]

Itlooks to be 2.5mm imperial old twin and earth.

It's not 4mm.

 

[Smellypunks]

Thanks for your reply Jurassic. Good to know thanks. So is that is a good match to modern 2.5mm solid core T&E??

 

[Jurassicspark]

. So is that is a good match to modern 2.5mm solid core T&E??

I won't say a "good match" but what you propose to do above is fine.

 

[plugwash]

I haven't heard of "copper clad aluminium" or "copper clad steel" being used for mains wiring in the UK (you often see it for cheap and nasty data cabling). Aluminium was briefly used but afaict it was normally solid cores and unclad.

Your stranded silver coloured cables are probablly tinned copper. Historically tinned copper was used to make cables, and I suspect that is what the "silvery" stranded cable you are dealing with is. My understanding is that the tinned copper helped prevent the cores from corroding with certain insulating materials and that after better insulating materials it took a while to fall out of favour.

It looks to be 2.5mm imperial old twin and earth.

There is no such thing as "2.5mm imperial old twin and earth". Imperial cable came in imperial sizes which were given as the number of strands, and the diameter of each strand in inches. Given that the OP's cable looks slightly bigger than 2.5mm² I suspect it's 7/.029 which has a CSA of 2.983²mm

No reason not to keep using it, but you need to be aware of the larger size and plan accordingly.

Wago 222's and Wago 41A Junction Box.

Not the best choice, I haven't personally tried putting "7/.029" in a wago 222, but it's larger than the advertised capacity and I remember even regular 2.5mm² being a pretty close fit with little room left over. It would not surprise me if it simply doesn't fit.

221-4xx series terminals on the other hand can accommodate up to 4mm² so they should handle "7/.029" fine. Unfortunately if you want to preserve the "maintinance free" status of the box while switching to 221-4 series terminals, you will need to either buy the adapter plates or buy the "wagobox 221-4" which is specifically designed for those terminals.

 

[Sparky3]

I haven't heard of "copper clad aluminium" or "copper clad steel" being used for mains wiring in the UK (you often see it for cheap and nasty data cabling). Aluminium was briefly used but afaict it was normally solid cores and unclad.

Copper clad cables were used in the mid 70's for a brief period. The core was aluminium with a copper coating, it was terrible to work with and didn't last long before it was withdrawn.

 

[Harry Bloomfield]

Now last week I switch a single to double socket downstairs and the T&E looked like 4mm Copper Clad (I am no expert but it was stranded and silver looking.) Only one photo showing the socket and the copper clad earth (note ignore the copper used to ground the backbox that was new).

During the copper shortage, they used next size up, aluminium cables. Some of which was copper coated aluminium. If you mean silver on the outside, then that will be tinned copper, probably 7/.029 - 7 stands of 0.029 thousands of an inch diameter, which was the standard used for a 30amp ring main circuit, at the time.

 

[morqthana]

Not the best choice, I haven't personally tried putting "7/.029" in a wago 222, but it's larger than the advertised capacity

4mm

Splicing connector with levers (222-413) | WAGO GB

Splicing connector with levers; for all conductor types; max. 4 mm²; 3-conductor; gray housing; Surrounding air temperature: max 40°C; 2,50 mm²; gray (4017332955676) Online at WAGO GB!

www.wago.com

 

[Smellypunks]

Thanks for the feedback everyone, interesting stuff. So it sounds like my plan still stands to extend the ring using 2.5mm T&E in the bedroom. The Wago box and connector do fit the old cable as I have used them to make safe the ring in the bedroom while I plaster the wall.

 

[Ragnar_AT]

Is it definitely a ring and not a 4 mm2 radial?

 

[Smellypunks]

Yes its a ring, I have had up a number of floorboards and have followed the cables between the sockets. I was wrong to assume it was 4mm T&E.

 

[Harry Bloomfield]

Yes its a ring, I have had up a number of floorboards and have followed the cables between the sockets. I was wrong to assume it was 4mm T&E.

The only way to be reasonably sure, is by testing continuity between the two ends, either at the consumer unit, or at a socket which is presumed to be on the ring..

 

[AndyPRK]

I’ve known rings in the equivalent of 4mm.

I guess it’s in large houses.

 

[Smellypunks]

@Harry Bloomfield I have a socket tester which I will use.

 

[Sparky3]

@Harry Bloomfield I have a socket tester which I will use.

That will not tell you if it's a ring or radial. Testing would need to be carried out with power off and the circuit conductors separated to check for ring continuity.

Out of interest, what size mcb/rcbo protects the circuit?