lead sheathed wiring

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writes

I suspect at least some of this cable is in such a state.

The old 1930's rubber sheathed cables in this house still 'worked' in that the lights still worked - but it was fire risk because the insulation was perished and literally falling off the wires and switches, junctions etc.
I find it very unlikely that the insulation round the wires in this cable is not also perishing in a similar way
--
Chris French, Leeds

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chris French wrote:

That's the odd thing. My ageing mothers house is wired with rubber cable in steel conduit. Where it gets exposed to the air, it goes brittle and crumbly, but it doesn't actually short unless you fuck with it. It holds is distance from the conduit. Inside the conduit it actually is not bad at all. I had to take a bit out a few years back, and it was only where it was in fresh air that it had degraded badly.
Since it is all well fused, and in steel, and properly earthed (good 50's practice) i judged it fine to leave. If it shorts, it will blow fuse. We stuck ion a new ring in teh kitchen some years back on a little cionsumer unit with MCBs etc. That all pukka 'modern' wiring, tho frankly the steel conduit is far better at stopping a drill bit...:-)
PVC can degrade - see polystyrene threads - as much as rubber can. Arguably encasing the lot on steel is far better than running an earthwire down the middle as T & E. Its not safety that has stopped steel conduit, but the expense of laying it. Lead coated wire is that way to stop fire hazards. Because the insulation can break down, abnd because they didn't have RCD's in those days, or MCB's - just bits of fuse wire.
In its day it was 'best practice'. Along with perfectly adequate 15A and 5A sockets and 3A sockets .
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Degradation is caused by ozone. There's a small amount around all the time, but sparks at switch contacts generate more which has a significant effect at those points. Rubber insulation was always completely unusable in mechanical telephone exchanges where the tiny sparks increased the background level and the rubber disintegrated extremely quickly -- in some cases where it was used by accident, its life was less than a year.
--
Andrew Gabriel

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Lead cable isn't 100 years old, and I can assure you it deteriorates. The lead sheathing and conductors may be ok, but the insulation which is rubber based will be perished and dangerous where it's exposed. Ie, at every termination.

I've not yet come across any PVC cable in ordinary house wiring which has deteriorated badly with age - assuming it's not been overloaded. But *all* the previous types of cable - yes. PVC has now been on the go just about as long as any other type.
As regards rodent damage, I'd be equally as worried about other things in a house if you're playing host to them.

But it wasn't wrapped in only cotton. And I've had plenty of things made of cotton which disintegrate too.

If PVC was so poor for this job, other things would still be used. Don't think it's a legal requirement.
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Dave Plowman snipped-for-privacy@argonet.co.uk London SW 12
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Its newer than that. I keep unearthing it as I rewire my house and that wasn't built until 1948. Mind you a lot of the building materials used look as if they were left over from before the war so this might be the same. Have also found rubber covered. Don't know if they used both or if one was added later.
Fortunately the previous owner had the house rewired (if one surface socket per room can be called rewiring) so all the lead cable I come across has already been disconnected.
Andrew
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    andrew_d snipped-for-privacy@hotmail.com (Andrew May) writes:

As far as I can see from my 1900 house (which was gaslamps originally), the first wiring used lead sheathed for the socket outlets on the ground floor, and rubber sheathed for the lighting. It might be that lead sheath was used where the cable is layed on the earth under the floor -- I haven't seen any remaining signs of old socket wiring for the first floor, or more likely, it was used where earthing was needed (i.e. sockets and not lighting at that time).
Incidently, for amusement I have dissected some of the lead sheathed wiring and it's still in perfect condition, although all the cable ends have been cut. If it was still wired with exposed rubber insulation at terminations, I expect that would have gone brittle, but where protected by the lead, it hasn't.

Likewise.
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The oldest wiring remains I've come across were in a dentist's family practice in Tooting. The dentist reckoned his grandfather had had electricity installed and it was the first in the area at the time. It was a sort of cotton and rubber mix insulation, but installed in wooden conduit - rectangular in section split horizontally with grooves for the single cables.
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wrote:

I've found this once - the back section had the two grooves, the thin cover strip had decorative grooves moulded on it so you could install it on the surface without it looking too bad -: the ancestor of mini-trunking. 100 times neater than surface run slip joint conduit which I have seen in local houses - probably when they were converted to electricity between the wars
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Andrew Gabriel wrote:

Thank you.
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At a guess pretty lethal One consolation would be the cash back when you take lead to scrappy.
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mark al wrote:

Why? If it works, use it. Its a lot less likley to catch fire if it shorts out, and anyway, you have MCB and RCD protection don't you?
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It isn't current practice (no pun intended) to install lighting circuits with RCD protection, except when using TT circuits.
Christian.
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Christian McArdle wrote:

I hoiuht it was standard to put the whole house on a 100mA RCD.
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Only on TT, which isn't common except in rural or ex-rural areas.
Christian.
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Most council estates and indeed many "private" housing areas in the Liverpool area have cleated wiring.
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It's at least 60 years old, IRRC. The condition it's actually in will depend on many things, but I'd say that on the exposed ends the insulation will have well and truly perished by now. Cut it back a short way and it might well be in perfect condition.
It's in general much more disruptive to replace lighting wiring than power which is why it often gets left on a bodged job. But I'd replace it sooner rather than later.
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Yes I had a length of Lead sheathed cable in this house - part of a ring main (probably of about mid 1960's date), it seemed to have been reused, everything else was PVC.
Certainly the insulation on the exposed cable ends was perished, though not quite so bad as the original 1930's wiring in the lights.
After almost suffering a fire on a connection on the old rubber sheathed cables in the loft I certainly would not want to leave any cables with suspect insulation in place for longer than i had too.
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Chris French, Leeds

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I suppose they must have made lead cable of ring main size, but all the stuff I've come across was lighting only - single core, I'd guess 0.044in.
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Dave Plowman snipped-for-privacy@argonet.co.uk London SW 12
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wrote:

Hi. Going back pre-1930s the power sockets may have been 2 pin 5A non polarised, and of course not wired in rings. Each would have a fuseway on the fuseboard. In some cases there were only one or two sokets in a whole house. There should also be a main on off switch, but that may be it. There might not even be an earth on basic installs like that.
Regards, NT
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wrote:

Definitely used to Dave - my Mums house was entirely lead - the cable runs were a work of art, seemed a pity to rip it out. The area that nearly caused a fire was where the cable went into the old bakelite fittings. My sister noticed a p*ss smell when the light was on in her bedroom......
Steve
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