Just a thought regarding cables of a past era.

[Pete999]

Just a thought really, there have been several posts, where Guys have been asking, what type of cable is this, that or the other.
Now is it just me or do members think we are coming to the end of an era whereby some of the younger Electricians/Domestic Installers, have not seen or heard of the type of cable some of us elder statesmen have experienced.
For example in years to come when many of us Old Lags have gone to the great Electrical Wholesaler in the sky, will there be some other type of cable, especially in the Domestic installation area i,e, non PVC, and people are asking the same questions then as they do now. You can imagine some keen young upstart has come across some 2.5mm2 PVC/PVC cable and wonders what the foook it is.
Do members think that some of the training courses should, at least give some time to the older type installation practices, rather than just teach, how it should be done, and if it bears no resemblance to modern cblas, just rip it out and start from scratch, what do you guys think?

 

[Lucien Nunes]

Another consideration, regarding the age of a installation cable, is the length of time it may have been exposed to Mr DIY'er.

This would usually be my main concern. The cable itself might be in great shape, but the longer it's been around, the more hidden damage is likely to have been inflicted on it by mice and men. Badly repaired nail holes, sneaky bits of choc-block where points have been moved - not all will show up on test on a dry day.

Aside from known failure modes such as green goo, properly installed cables are likely to well exceed the manufacturers' rated life because that will be a worst-case figure. Insulation deteriorates through both physical and chemical processes but taking some of the chemical ones for example, the rate of reaction typically halves for every 10°C reduction in temperature. On that basis (which admittedly is not the whole story) a 70°C cable rated for 25 years life could last 200 years at 40°C. But if there's a badly installed section that is heavily bunched causing it to run at 60°, then that section will only last 50 years. No ordinary EICR is going to spot every problem area of this kind so a pessimistic figure is probably sensible.

As for sparks being unfamiliar with old materials and methods, it certainly wouldn't do any harm for courses to include a bit of background. OTOH if one is going to do EICRs, basically a surveyor's job, one should continually read around the subject and take opportunities to examine carefully every kind of material and technique that can be found.

 

[Midwest]

Er no ..... a thorough EICR should be conducted.........

But that's my point or argument really. If a cable is given a life span of twenties years, why spend money on an EICR, for a 50+ year old installation. Why should I give you £***, on something I already know.

Going back to my opinion, if I moved into such a property, I would rewire it. When people move into an old house, first thing they do is replace the aging gas boiler, when the old one is probably no less efficient, or it will take some time to recoup the cost.

I can see the point for an EICR, on a large rambling property, but your average 3 bed semi, I'd rather spend the money elsewhere.

 

[Pete999]

This is quite a timely post @Pete999

I was going to post a pic with a query, so here it is:-

View attachment 37882
I'm not 100% certain because I've not had cause to open any of it, but based on how flexible and light it feels, and how it sags between the joists, I have a sneaky feeling this is some form of aluminium. I couldn't find any identifying information on it, just the makers mark.

Any suggestions?

Sorry SC missed this so excuse the delay, you may be right in your assumption, it could be copper multi stranded stuff, the round single looks to me like an insulated and sheathed cable used a lot in lighting wiring, but you're right without opening it up it would be hard to tell, There is a way that may give you a clue, have a look at the connections at sockets, switches and even at the C/U, may throw some light on the subject.

 

[Pete999]

This is quite a timely post @Pete999

I was going to post a pic with a query, so here it is:-

View attachment 37882
I'm not 100% certain because I've not had cause to open any of it, but based on how flexible and light it feels, and how it sags between the joists, I have a sneaky feeling this is some form of aluminium. I couldn't find any identifying information on it, just the makers mark.

Any suggestions?

Sorry SC missed this so excuse the delay, you may be right in your assumption, it could be copper multi stranded stuff, the round single looks to me like an insulated and sheathed cable used a lot in lighting wiring, but you're right without opening it up it would be hard to tell, There is a way that may give you a clue, have a look at the connections at sockets, switches and even at the C/U, may throw some light on the subject.

 

[freddo]

The local college apparently doesn't even teach the old cable colours, one of our apprentices didn't know what red and black were, and assumed red was neutral!
I have collected loads of old cable samples over the years, one day I'll get around to making a nice display.

 

[sparkdog]

I really liked the old 3.029 & 7.029 with stranded tinned copper, much better than modern solid core.

 

[SparkyChick]

Thanks for the info on Pyro guys. I may just buy some gear and have a practice with it for the fun of it

@Pete999 , no worries on the delay, it's the weekend and we all lag at some point

Hope everyone had a good one. Looking forward to wrangling some 25mm 3 core SWA later today, getting ready for a supply move

 

[Sparkgap]

The copper crisis in the 70s saw a lot of ally cable used which came back to haunt us with fractures and high-res hotspots in following years! They even produced copper coated steel pipe which you supposedly could solder just like ordinary copper pipe but which is an absolute bu99er when you come across it years later.