Aluminium Cables again. Ugh!

[Piratepete]

Hi Guys.
I've just replaced an old rewirable Wylex consumer unit in a house with all pvc/pvc T&E solid core aluminium cables. 2 rings on 30 Amp fuses, 2 lighting circuits on 5 amp etc. The cables were in good condition (at the box at least) so no probs. A couple of earth continuity probs to sort.

But, the core diameters seem to be identical (within 0.05mm) to copper cables; ie. the ring core lives are 2.5 sq mm and the earth is 1.5 sq mm. I expected larger to get the copper equivalent.
Does anyone know what the rating of these cables is. What alu wire sizes were used back in the 70's for sockets, lighting and cookers? What were their current capacities?
I don't have access to old regs (early 15th?) to check.
Thanks
Pete

 

[rocker]

Hi, there are tables for alu conductors as well as copper in the back of the BRB

 

[Engineer54]

Never seen ALUMINIUM solid cored T&E, only stranded. The ally equivalent of copper 2.5MM T&E is 4mm with 2.5 cpc , the cooker ally size was 10mm. That's about all i can remember of the ally era of house wiring..... I suspect your installation isn't to spec, if you were seeing solids everywhere!!!

 

[PC Electrics]

The ccc of aly cables is roughly 0.75 times that of the same size copper. I'd suggest 20A MCBs for those rings.

I too did a new CU recently where there was some aly wiring. The cables were 1.5/1.0, however the cpc was copper with aly line and neutral.

There are no tables for small sizes aly t&e in either 15th, 16th or 17th regs that I can find.

 

[miner69er]

Be careful here: Aluminium conductors have their own type of connector. ie. a screw which pinches the wire is no good as it will bite straight through the aluminium, it should have a plate in front of the screw to clamp the wire not pinch. Also i have found the aluminium conductor very susceptable to breakage and loose connections. To be honest, it should be a recommendation of a re-wire (in my opinion anyway) as the homeowner will try and fit accessories which only have the screw to pinch the wire as this is all most big orange shed types offer. This is the reason that BS7671 (big ol' red) does not have any information regarding aluminium conductors under 16mm.... They are not to be used anymore.
Not trying to preach, just a word to the wise that's all.
Just a thought.... they are aluminium are'nt they? because there is a lot of copper with a type of plating, looks just like aluminium until you look at the cross section and see it's copper with plating.

 

[Piratepete]

The cables were 1.5/1.0, however the cpc was copper with aly line and neutral.

Talk about a cable design made to confuse! So many variations in the use of ali!

 

[rocker]

miner makes a good point, are you sure they are ali and not tinned copper?

 

[madmac]

Remember back in the seventies there was a copper shortage from China and that's why houses from that era have stainless steel pipes and aluminium cables?
Just thought I'd stick that one in there lads, sorry for being ---- about it.
Also agree, make sure you're not talking about tinned, copper cables.

 

[Piratepete]

miner makes a good point, are you sure they are ali and not tinned copper?

Aluminium without a doubt. And the owner has had problems with connections for years!

 

[Graeme Harrold]

Have read an article recently that ally could be making a come back thanks to the rising price of copper......