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Working life span of twin; and twin & earth cables.

Sparkingchip
We have not had a discussion lately about the anticipated working life span of PVC insulated twin; and twin & earth cables lately.


Given that many installations have PVC insulated twin; and twin & earth cables that are now over fifty five years old if we issue a satisfactory EICR with a recommendation to retest after five years the cable will actually be over sixty years old by the date the retest is due.


How much consideration do you give to putting in writing that you consider that sixty year old will still be okay to use?


 Andy B.
  • 0
    BS6004 was first  published in August 1969, what preceded it as PVC insulated cable was already in use?


    Andy B.
  • 0
    If the cable is fine at 55 years, the chances are that it will be just as good at 60 years.
  • 0
    Well, i am older than that cable and i am still ok for continued use! (Well thats my story and i'm sticking to it) . 

    i'd think that modern pvc cable is ok providing not abused. If we stick to good practices it should be ok for a few more years yet I imagine
  • Former Community Member
    0 Former Community Member
    Sparkingchip:

    We have not had a discussion lately about the anticipated working life span of PVC insulated twin; and twin & earth cables lately.


    Given that many installations have PVC insulated twin; and twin & earth cables that are now over fifty five years old if we issue a satisfactory EICR with a recommendation to retest after five years the cable will actually be over sixty years old by the date the retest is due.


    How much consideration do you give to putting in writing that you consider that sixty year old will still be okay to use?


     Andy B.


    I will consider after done with several testing including the life. span of PVC. If not, write in KIV. 


  • 0
    I can see no reason why PVC cables will not last indefinitely, as long as they are not damaged by bad environment or serious overheating. It is true that plasticiser is slowly lost, making the cable stiffer and more brittle, but the insulating value is unaffected. The insulation value should be much higher than 1M Ohm, but the colour, stiffness etc do not matter. Cables outside subject to sunlight may suffer surface damage, becoming rough, but this is trivial UV effect on the PVC. The situation of old rubber cables is very different, but good examples from the 1930s still exist and are in use. Cables are very rarely the proper reason for any kind of rewire whatever an EICR may say! My own house has some fairly old PVC cables from the early 70s which are as good as new (I know because I installed them), although the core colours are red/black which I prefer to the brown/black/grey/blue forced on us by the EU. Insulation resistance is >1000 M Ohms at 1000V for all lengths.
  • 0
    I'm inclined to agree- the enemy of modern plastic cables is overload or damage. In that sense the cable life is often determined by the user,  if extra loads are added, or the cable is painted over with creasote or nailed through or similar. 

    Cables that run cool, away from rodents and UV light may last for several centuries - in practice, like bricks,  for the life of the building. (or until the building is re-purposed)

    Junctions are probably a weaker spot.


    Wiring in cars has a shorter life, as it current ratings are determined based on a higher copper temperature (105C in some cases), but this does not matter, as cars do not last that long.

    On the current track record it is quite possible that future generations will come and marvel at 20th century wiring much as we admire old cathedrals and so on, and say "you'd never get craftsmanship like that now"!  in awed voices while  looking up at the basket tray and twin and earth across the warehouse ceiling . Well, maybe not that last bit.


    Some early plastic compositions were not as stable as today, so it is certainly worth looking at the cores for signs of  decomposition, especially with cables that pre-date the 1970s. There are some that have a 'green goo' failure mode where the plasticiser leaks out and corrodes the copper.
  • 0
    mapj1:

    I'm inclined to agree- the enemy of modern plastic cables is overload or damage. In that sense the cable life is often determined by the user,  if extra loads are added, or the cable is painted over with creasote or nailed through or similar. 

    Cables that run cool, away from rodents and UV light may last for several centuries - in practice, like bricks,  for the life of the building. (or until the building is re-purposed)

    Junctions are probably a weaker spot.

    I agree with all of that. Short of rodent damage, cables under floorboards might well last indefinitely. It's the ends that suffer. A requirement to re-wire may be due to poor installation, water ingress, damage to wiring, repurposing of rooms (leading to repositioning of wiring accessories, especially in kitchens), etc.

    Wiring in cars has a shorter life, ... as cars do not last that long.


    Modern cars may not last long, but there are plenty of one hundred year old cars in existence, although granted most will have been substantially if not completely rewired. Come along to a Vintage Sports Car Club event if you want to see some! ?


  • Former Community Member
    0 Former Community Member
    My dad fully rewired their house in 1978 , the wiring is as still like new.

    i changed the Fuse board about 15 Years ago and everything tested up like new.

    i have absolutely no doubt if I did an eicr in 20 years time it would still test up just fine.

    so to answer the question imo modern pvc pvc twin & earth should last a lifetime.
  • 0
    It nearly has!
  • 0
    I was having trouble with the topic title and it should read more like:


    Working lifespan of PVC insulated & sheathed singles, singles & earth, twin,  twin & earth and three core & earth cables.


    Andy B.

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