I live on a development about 30 - 40 years old. The electricity company are laying new cables to the little substations. It is a twisted trio of red cables. I am curious as to what may have triggered this: Age of the cables? Inadequacy of the cables? If inadequacy how would the electicity supplier know? By logging the loads? Seems a costly job and we have had no powercuts
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.
Chris K
DerbyBorn wrote:
Maybe they are getting ready for new builds somewhere. Brian
That sounds like the 11kV feed between substations. There are usually several paths, so some are redundant, and you wouldn't necessarily lose power if one failed, but left like that, redundancy is reduced.
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).I played what I think of as one of my new CDs the other day, and then worked out it was 20!
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