On 13/04/2018 00:27, Dave Plowman (News) wrote:
In article ,
ChrisK wrote:
They hat to rewire our development (mid 1980s build) a few years ago
after repeated failures and mini explosions.

Apparently, the original installers were not familiar with a new style
of cabling introduced at the time resulting in poor quality joints.

Interesting. I've lived in this house since the 70s and the cabling into
it looked old then. Nor has the road been dug up to replace that running
down it. It may have had localised repairs, though. Which does make me
wonder what the life of this stuff is?

I rewired internally when moving in - and have suddenly realised that
wiring is now about as old as the lead covered stuff I replaced. ;-)


As to the life of PVC, the answer is of course that it all depends. It's
easy to see by experiment that it hardens and becomes brittle at ~80C,
just as we know that "old" natural rubber will be after a few decades at
ambient temperature. But actually, if that is lead covered and not
significantly disturbed, it will keep working.

For industrial purposes people tend to talk about PE, ABS, PVC etc
having a life in excess of 30 years at temperatures below about 50C. I
investigated a failure on a power station some years ago on some water
circuits which were plumbed in solvent weld pipe from 3" to 8" in a
mixture of ABS and PVC (each "run" was just one material). Over the
years they had replaced some of it with stainless because of failures
(including mechanical damage). The failed pipe had a brittle failure
associated with the axial join left by the spider which was used in the
extrusion process, but tests showed that it wasn't obviously any more
brittle than new material. It had done about 40 years at temperatures of
20 to 30 C. IIRC the claimed life was 30 years (but of course that was
really only a guess as these were new products with no history when they
were put in).