Discuss "Electrical cables have a life, 15 to 20 years." in the Industrial Electrician Talk area at ElectriciansForums.net

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I'd say visual inspection especially at the accessories is equally important as testing but if insulation integrity is good then time is but an abstract.

I expect its just as Lucien has said. If this is a press article then the chap probably said something along the lines 'cable has a rating of 20 years'. I doubt the word 'rewire' ever came up until the journalist decided to embellish.
 
Inspection and test, not just testing. Some absolute horrors can test out fine but not pass inspection.

Spot-on...i was reminded of one,on reading this^ A radial in VR,to a water heater cupboard,where ALL the insulation had crumbled off,on an 8" section below.

A combination of age,temperature and stacked towels,rubbing away...

IR readings were excellent.

As with most things,a combination of factors,affect the outcomes of test/inspection,as they duly affect the safe working life,of any given cable.
 
Inspection and test, not just testing. Some absolute horrors can test out fine but not pass inspection.

Indeed, and remembering that inspection is actually the more important part of the process! Testing merely supplements the inspection.
 
I mean physically not electrically, running cables in close proximity to each other causing overheating, when the circuits are in use.

Yes, which is what grouping factors are applied for. But you mentioned running T&E through joists domestically where it wouldn't apply due to the nature of the usage of the circuits
 
With regards to some cables he is right, some PVC cable is only expected to last 20 years, others up to 50 years, the way PVC degrades is a difficult one, you may test and everything is fine, 5 years later not so due to degradation.

I think any house wired in the 60's to 80's need to consider a possible rewire especially if the house is to be renovated at considerable cost, these cables are 40 to 50 years old.

Also is the current installation really adequate for today's needs.

Read this BASEC

There are no requirements for life expectancy set out in cable standards and specifications. However, reputable cable manufacturers will state a probable life expectancy for their products, which for building wiring is usually 20 years when run at the rated temperature. However, under ideal circumstances, with lower loadings and minimal heating, it has been observed that cables can remain safely in operation for up to 50 years.
Cables degrade over time primarily due to changes in the polymers used for insulation and sheathing. The main cause of polymer degradation is too much heat, from either excessive current loading or from the environment - such as heated spaces. Cables loaded or heated for 24 hours a day will degrade faster than those used only during working hours – for example, commercial lighting circuits are often operated continuously.
If cables are overheated or overloaded it is possible to estimate reduced lifetimes. For example, regular PVC installation cables might last for 20 years if used at their rated temperature of 70ºC, but this would reduce to seven years at 80ºC and a matter of months if operated above 100ºC.
The conductors of a cable will normally maintain their performance indefinitely, but if accessories are changed frequently, crushing damage may occur to the exposed ends. Corrosion can sometimes occur with aluminium conductors and rusting can also affect the conductivity of steel armour.
Cables mounted or used outdoors are prone to very rapid degradation by UV exposure, so it is important that a type recommended for outdoor use is employed.
When deciding whether cable should be replaced during a refurbishment, installers and end users should not just look at the cable as it is now, but consider the possibility of degradation and failure in the period before it is next likely to be assessed, which might be another 10 years. If a major refurbishment is underway it may be less disruptive to replace cables now, rather than take the risk.



Cheers
 
So everything built 20 years ago or more is in urgent need of rewiring??
Baw locks. IMHO.

Read the full article.

He does say the condition of the cables are unknown, so 20 years is what the industry state as an expected life span, testing and inspection would be required to tell you if its urgent, i suspect he has no knowledge of the condition, so hes made a speculative comment , is he really going to say anything different than what the cable manufacturers and associates recommend?

Cheers
 
Inspection and test, not just testing. Some absolute horrors can test out fine but not pass inspection.

When I say tests out, I mean tests out fine and all visibly fine too. Obviously I am not going to go digging in walls and floorboards looking for problems, but so long as its all safe and sound its good to go.
 
Well, I'll tell you now, that the cables are the last things that need pulling out of there and chucking on the scrap heap. The shower of sh1te that has been masquerading as a government for the last 50 years and progressively sold off and fooked the country up need recycling, not the cables. Sorry, couldn't resist it.
 
Just before Christmas I returned to a house I had re wired back in 1970 I was just an apprentice at the time.
Daughter of the couple that had lived there all those years asked for it to be re wired once again, the couple had passed away a few years back.
I was 17 on the first re wire, 63 now. Talk about a trip down memory lane.
I remember on completion thinking to myself, I won't be doing the next one.
Unless Dewalt do zimmer frames lol.
 
He was speaking in context, that context being that manufacturers place a nominal lifespan on their products. What you read was one sentence.
 
He was speaking in context

I think he was speaking out of context. The article was talking about a specific installation, and he gave what is perhaps a worst-case specification that rarely applies to installations of the type being discussed. Had he said: 'Cables can usually be counted on to last 20 years, sometimes they last much longer, but it all depends on their working conditions' the uncertainly would have been explained for the lay reader.
 

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