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Is there a CCC comparison table for old stranded wires anywhere?
I have a domestic installation, about 40 - 50 years old I wd say, and there are only 4 circuits, one is the sockets, with 2 wires into a 3036 30A fuse. I assumed it was a ring but it isnt, its not connected. The break is between the kitchen and rest of the house and theres been a kitchen conversion done, so Im assuming the fitter has bodged the wiring in a junction box somewhere. But is it possible its 2 radials, 1 for kitchen and 1 for the rest? The wire is 7 strand silver colour, so aluminium? but elsewhere in sockets there is a mixture of stranded and solid red and black.
I havent got the means currently to measure each strand (im going to get a micrometer, any suggestions from where?) but the overall wire size compared to a solid 2.5mm does look bigger.
The customer has had no fuse blowing problems (there again he probably wouldnt) but I told him it looks like the ring has been broken and needs re-connecting but I need to check...

The largest R1R2 reading on the circuit is 0.72 ohm and the largest Zs is 1.09.. phew! Ive fitted a dual rcd box, put the two socket wires into one 32A fuse as before temporarily and there are no problems on test results, apart from obviously no ring. No signs of charring at wire terminations either..
 
Note that the Richard Burns tabulated CCCs are for "Close Protection". A BS3036 fuse is classed as "Course Protection", so you need to divide (or de-rate) by a factor of 1.33, according to the 14th edition info I have.

That means 7/0.036 is OK for a 30A radial if clipped direct, but 7/0.029 is not.

The pdf posted by tony mc shows both the "close" and "course" values.
 
Note that the Richard Burns tabulated CCCs are for "Close Protection". A BS3036 fuse is classed as "Course Protection", so you need to divide (or de-rate) by a factor of 1.33, according to the 14th edition info I have.

That means 7/0.036 is OK for a 30A radial if clipped direct, but 7/0.029 is not.

The pdf posted by tony mc shows both the "close" and "course" values.

Thats what I thought, although the protection is now 60898B, so that is presumably classed as "close protection"?
 
7/.036 can take 31A I think, I'll check

So 7/.036 looks ok but if the wire is 7/.029, and can take 29A as per the list from tonymc , would this be allowable for 2 radials for sockets in the new consumer unit? As thats what its been doing for years with no problems on one 3036 fuse?
Or do I insist the client has to connect the two radials into a ring? which he doesnt want to do particularly, and you can understand why..
 
So 7/.036 looks ok but if the wire is 7/.029, and can take 29A as per the list from tonymc , would this be allowable for 2 radials for sockets in the new consumer unit? As thats what its been doing for years with no problems on one 3036 fuse?
Or do I insist the client has to connect the two radials into a ring? which he doesnt want to do particularly, and you can understand why..

If the cable and Ref Method allow it, Just set it up as 2 20amp radials.
 
If the cable and Ref Method allow it, Just set it up as 2 20amp radials.

Or two 25 A radials even, yes I did think that was an option but not sure if the kitchen radial would take it without occasional MCB tripping. 3 appliances at once would probably do it.. But maybe the client will prefer that to the disruption of connecting a ring. There would be chasing involved..
 

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