Not so old or very old cable?


Postby misterg » Sat Jun 30, 2007 10:02 pm

Hi

I have been moving some sockets and have a question about cable.

The existing cable used to wire the ring circuit looks a lot like moderm cable, i.e., grey sheath, twin core and earth. It is 2.5 mm cable, however it the cores are not single stranded, they are multi-stranded (a bit like a modern 4 or 10mm cable). Also the cable is a bit more flexible that the new cable I am using.

Is the above likely to be rubber, or was earlier PVC coated cable more flexible?

It does not appear to be crumbling, which I was told was a sign of very old rubber wiring.

Cheers

G
misterg
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Joined: Sat Jun 23, 2007 8:58 pm

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Postby sparx » Sun Jul 01, 2007 11:27 am

Hi mesterg,
old power cable as you describe is prob. 7/.029 inch2 which if grey is pvc not rubber which was always black,
white & grey were used depending on where it was being seen, unlike now where grey is normal cable & white is low smoke/fume (costs more).
old pvc much more flexible & usually easier to strip (progress?).
When introduced in early 1960's we were told life 'infinite' if not overloaded, unlike rubber which had a normal life of around 30 years, unless touched by plaster when it was reduced seriously by lime in plaster.
you have 7 strands of 0.029sq inch cross section area = 2.5mm2 today
other sizes being: 1/044 = 1.0mm, 3/029 = 1.5mm, 7/036 = 4.0mm,
7/044 =6.0mm, 7/064 = 10mm, 19/044 = 16mm, bet you wished you hadn't asked!! regards SPARX
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Postby misterg » Sun Jul 01, 2007 4:09 pm

Thanks Sparx

Looks like the house musty have been rewired at some point, which is good, as it was built in the thirties!

Existing cable looks in good condition, it's all been run under floorboards, trhough joists or in metal conduit, so shouldn't have issues with plaster.

Where it goes near central heating pipes, the pipes have been lagged, so hopefully will mean it's all good.

Thanks again.

G
misterg
Posts: 49
Joined: Sat Jun 23, 2007 8:58 pm


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