Jumping to conclusions...

Even with 1mm^2 T&E, the cable is way over specced for a 6A MCB in terms of total current handling. 1mm^2 will handle 16A with a "clipped direct" installation method. 1.5mm^2 will do 20A.

On low power circuits like these, it is the mechanical robustness and voltage drop that matters rather than the power handling.

Yup. nothing wrong with the standard circuits - they save lots of checks and verifications while producing something that will "just work" and behave (and fail) safely.

However if you take the time to *design* a circuit for a particular application you can find you can get way more performance out of a given configuration than you might expect (or conversely meet a performance requirement at a significantly lower cost than you may have expected).

In this case the circuit was already there, and had been designed originally just for a lighting application. However a quick bit of design checking showed that it could safely be extended to also feed a socket. (which worked just fine when the cables were not full of water!)

(a) to reduce energy consumption

(b) some of the 1.0 mm2 had seemed to have stiffened and upon dissection found to have tarnished copper so I cna only assume some form of resistive heathing or a bad batch of cable from 1985.

P.S. and where the old cable had stiffened, the outer sheath was also discoloured.

Indeed. I went nearly all LED years ago - however some lights are best left alone.

Resistive heating does not care if it is 1.0 or 1.5 T&E

It just takes a little longer to warm it up:-)

Can't see the sense.

Bill

co incidentally, we had a new CU in a new location with 16 RCBOs to replace the old CU which had just 6 MCBs and 1 RCD.

So the opportunity was taken to sort the 1.0 mm2 T&E at the same time once the sections of stiffened & discoloured were found.....

Nothing wrong with replacing damaged cable, but uprating the cable size while systematically reducing the maximum load to a tenth of what it was, might fall into the "overkill" category :-)

When we moved in here we were a bit surprised that there seemed to be two lighting circuits for the ground floor. Each protected by 5A MCBs (Old Wylex NB type 2 style MCBs).

Then we realised that they had installed so many multi lamp fittings, that the huge number of incandescent lamps would trip the circuit - hence why they split it. (not very equally as it happens)

yes, it may be "overkill" but it leaves me with plenty of room for expansion......

e.g. I have 10 mm2 buried SWA running for 10 m from the house to the wood store shed and greenhouse.

That currently powers 4 LED floodlights and a double socket.

Ditto 25 mm buried blue polyethylene water pipe currently used for watering the greenhouse

If I decide to have an outdoor heated spa pool, the power and mains pressure cold water is already there.....

I always find it amazing where the elements will get in to stuff. It seems not to matter how careful you are, whether its heat expansion and contraction or whatever water gets in. Another thing that seems to defy logic is how water gets into aerial cables and connectors after some years. Its almost as if the cable material is made to self destruct and get little nicks to allow the water in or the interface to the connection boxes at the aerial end are designed so that water can trickle in. Brian

Brian, ignore Rod's response. He's just feeding his ego again. I think an element of his pathology is that because you're blind he sees you as defenceless.

Ordinary TV aerial cable does somehow manage to take in moisture through the sheath. This is only a problem if the cable is either immersed in water or buried in damp ground. I assume that when the cable is in the open air the average humidity isn't enough to drive significant ingress. When an immersed or buried cable is cut open the evidence is there: discolouration of the screen, the dielectric, and the inner, usually confined to the sections of cable that have been buried or immersed. Interestingly, even when there is no free water in the cable (it's apparently dry but discoloured) signal transmission is affected, sometimes catastrophically. The old type of foam dielectric is the worst for this. Apparently the air spaces in the foam are contiguous, unlike in modern cable.

I can only think that water gets through the plastic sheath one molecule at a time. This is why 'direct burial' cables exist, of course.

Bill

Which means you're stuck for words.

And you know all about it I suppose. OK, aerial and satellite cables often run across flat roofs that don't drain properly, so the cable is immersed for much of the time. Some installers routinely run cables inside gutters which can have standing water much of the time. Distribution cables between buildings are usually underground, and yes, some installers/builders don't put them in ducting and don't use direct burial cable. Some cables, both domestic and distribution, pass through areas that have such high humidity all the time that the cables suffer moisture ingress even though they appear dry (or as dry as anything else). Examples are cables in voids that carry district heating pipes, cables that pass through large boiler rooms (district heating, hospitals, etc) and in one memorable example a cable that went above the sus ceiling of a school kitchen and became 'lossy' after only two years.

I have many photographs of these things because I used to have to explain to building managers what had caused the problem.

Because the average moisture content of the environment means that water molecules aren't driven unilaterally through the sheath. I dare say if it rained almost all the time the result would be much the same as if the cable was immersed. In England it only rains for 8% of the time.

Just remember, Rod, that you know f*ck all about this and I have had a working lifetime dealing with this sort of thing. I know you get your rocks off by browbeating people by shouting 'You're wrong!' and 'You're a f****it!' but it won't work against the genuinely knowledgeable.

Bill

I once replaced the steering column lock barrel on a car. Some scrote had broken in and made a mess of it.

Could I get the car to start?! No. Naturally assumed it must be down to what i'd been doing.

Much faffing and testing later I got an auto electrician out. He lifted the bonnet... "No mate I said..." but he stopped me and explained he has a cast iron system of working through a diagnosis like this and seconds later he found a wire had come away by sheer coincidence at the starter motor.

I may have told this tale before? hopefully it wasn't too recently!

I don't recall you mentioning it, but that might just indicate a shared failing of memory!

You are an insecure blathermouth with an inferiority complex.

You don't need to know about something to shoot your mouth off about it. I see...

You obviously have no experience in this area. Replacement of water-damaged cable is a major part of an aerial installer's work.

'Bullshit' mean 'no answer'.

It's very common indeed. It's a bad habit of the installers employed by a major satellite company, amongst others.

Almost universal practice where a number of blocks share a system. Many developers and planners don't like dishes and aerials on every building.

No I didn't.

No I didn't. The examples I gave weren't exclusive.

There is such cable, It's called 'direct burial'.

We don't use it. We just replace it when others have.

So what?

Bill

This is getting beyond ridiculous now. You're trying to prove black's white. You're arguing with someone who has been involved with the issues all his working life when you clearly have no knowledge at all. I think you're just being a pillock for the sake of it. You clearly don't actually believe your own words. You must have a very empty life, and a sad embittered soul.

Bill

Bill, Rod is doing an excellent job. He is by far the most persistent troll who seems to be able to get under the skin of folk who really should know better.

Since when did arguing with a troll ever achieve anything (beyond giving the troll pleasure)? Don?t you have a kill file?

Tim

Perhaps we all agree you're a legend in your own mind?

It's well-known that Woddles is a twerp.

It has always been his MO as far as I can tell. The more obviously informed the poster, the more he argues. Probably just attention seeking.

This is a problem easily fixed with a kill file, unless you particularly enjoy arguing with someone who is depriving a village of their idiot.