advice re existing alluminium wiring

[ianphilip007]

just a quick question.

i came across what i think is stranded (approx 4mm csa line concuctor/2.5mm csa protective condutor) aluminum wiring on a downstairs ring circuit. Customer is requesting 2 new sockets be added to the existing ring main.

Is it allowed to extend the the exisiting ring with 2.5/1.5 mm csa copper as per usual or are there any special requirements, apart from the care needed with the actual joint. Never come accross aluminium wiring before so dont want to make a stupid mistake. Cant find any clarification in the big green book re above

many thanks

 

[malcolmsanford]

First if it's stranded there is a good chance it is not Aluminium but copper tinted cable, of all the Aluminium domestic cable I've seen, which in fairness is not a great deal, it was always solid core. A good indication if it's aluminium could be where it terminates into the appliance there may be a little crudding up of it, or you can cut the cable and see copper.

Even if it is aluminium then providing your IR results are good, and there is no obvious signs of deterioration, then nothing stopping you just adding your addition.

 

[ianphilip007]

thankyou malcom, and you may be right re tinned copper as i have not had a close look as of yet.

 

[PC Electrics]

Some imperial cables were tinned copper and 7/029 (actual csa 3mm) looks very much like 4mm. iirc it usually has a 3/029 cpc. 7/036 (actual csa 4.6mm) sometimes has a 7/029 cpc.

Measure the diameter of a strand to determine what you have got:
029 = 0.74mm and 036 = 0.91mm.

You can check it's tinned copper by cutting a fresh end with a sharp pair of cutters and you should be able to see the coper wire (you might need an eye glass).

The ccc's are 31 and 41 amps resp.