Non-copper wire in ring main?

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Hello.
While adding some sockets to my wife's study, I've found sections of non-copper cable in my ring main. It's an old house, though the vast majority of the wiring is less than a few decades old.
The cable has multiple strands, perhaps about 7, and is made by Pirelli. I couldn't see a type code on it. It seems quite chunky, but I'm surprised to see that it is not made from copper, but is probably steel. Outwardly, it looks like regular grey T&E, but is more amenable to bending.
Is this cable normal? I suppose my concern is that this particular ring is quite long, and I understand that steel has a higher resistance than copper. The ring covers rooms containing mostly lower-powered items, but does include the washing machine.
Ewan
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Ewan MacIntyre wrote on Saturday (03/01/2004) :

I would suggest it is aluminium, which would be bigger due to greater losses and feel softer to bend. It was used in response to the high price of copper in the 1970's.
It did have problems with poor connections resulting in over heating, so it would be worth while replacing it with copper, along with the sockets. The only uses I have heard of for steel, was for telecoms where the steel was copper plated.
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During the Rhodesia crissis ( UDI etc 1965 onwards) aluminium was used in house wiring due to copper shortages - dreadful stuff - breaks easily at screw terminals. During the same period stainless steel was being used for plumbing.
OTOH are you sure that you haven't come across a bit of the old 7/029 used around then - seven strands of 29 thou copper that was usually tin plated - this was a pre-metrication standard.
Andrew Mawson
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Andrew Mawson wrote:

ISTR that was pretty standard in most house in the '15A round pin plug ' era...

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It was also used for the best part of 20 years for ring mains, too.
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Dave Plowman snipped-for-privacy@argonet.co.uk London SW 12
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Yes -- one of the design aims of the 30A ring circuit was easy conversion from a 15A radial system (by making the ring start and end at two existing 15A outlets, converted to 13A of course). Hence the two schemes used the same cable (and you were allowed to keep the two 15A fuses at each end of the ring early on too).
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Andrew Gabriel

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But it was also used on new builds which only ever had ring mains until the arrival of the current 2.5 TW&E - which was part of metrication.
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Dave Plowman snipped-for-privacy@argonet.co.uk London SW 12
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Andrew Gabriel wrote:

What's the story behind the switch from 15A to 13A sockets? Surely 15A would be more useful....?
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On Mon, 5 Jan 2004 15:37:17 -0000, R W wrote:

15A was radial and generally only one socket per room. Count all the sockets in a modern house then think about the size of the CU for that number of MCBs...
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Yes, but why switch from a 15 amp rated socket to one with a plug / fuse rating of 13 amps, in other words, why a maximum of a 13 amp fuse and not a maximum of 15 amp ?
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The design aim was for 3kW, which is where the 13A comes from. I guess there probably weren't any portable appliances over 3kW in use. Kettles of that era tended to be lower power than today's ones. I have come across a 3kW portable convector heater which could date back to that era, which is rather ironic as you'd be hard pressed to find one over 2kW nowadays.
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Andrew Gabriel wrote:

3kw convector were common in the 60's as were 3kw electric fires.
My ma's house was originally wired with 15A stuff (1953), then it was changed to 13A stuff - still on spurs - fairly quickly, and a few bodged extra sockets added. A seperate fuse box for the electric cooker was added when the gas one was binned.
The main wiring is still rubber coated plated copper stranded in steel conduit, and it has never shorted, or blown a fuse or anything.
The addons were done in the 60's using solid core stuff. Some by me.
None of it meets modern regulatons, but it all still works, and the earths are good. No doubt when teh house is eventually sold in teh next ten years estimnated, it will get a total reinsulate, rewire, new bathrooms, extension etc etc. But it still soliders on in remarkably good structural condition.
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Both mine and my mother's fan heaters are 3kW. They're pretty widely available. However, the cheapest in the range will be a 2kW, so they're probably more common to find, as most people are cheapskates.
As for convectors, a quick browse of argos shows five 3kW, one 2.5kW and four 2kW models available.
Christian.
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There's really no point in a 2kW fan heater, given that all have thermostats.
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Dave Plowman snipped-for-privacy@argonet.co.uk London SW 12
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Firstly, the output temperature is lower. It is very easy to melt nearby plastic things accidentally with a 3kW.
Secondly, after the room is up to temperature, I tend to knock the power rating down to reduce cycling. I prefer the constant noise to one that goes on and off every five minutes. If half the power of the device is too high, then this will be less effective as it will continue to cycle rapidly.
Christian.
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Err, I think that last point is one that supports a 3kW fan heater! You can only get up to temperature quickly and then turn the heat down with a 3kW heater (or it's better at it). You can run a 3kW fan heater at 2kW but not the other way round! I grant you the first point, especially if there is a danger of things getting dropped near it (children's toys, things dropped by older people, middle-aged drunks falling over etc).
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Bob Mannix
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I think you have misunderstood. In a room with a 1kW steady state requirement, a 2kW heater will bring it up to temperature and then, on half power, will be able to maintain it using only a minimum of annoying cycling.
A 3kW heater will bring it up even more rapidly. But then, turned down to 1.5kW, it is over sized and will switch on and off over a 3:2 duty cycle with a period of a couple of minutes.
Christian.
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Well, it's not worth falling out over but (a) you didn't originally stipulate the room had a 1kW heat load and (b), on my 3kW heater at least, you can run the 3kW heater at 1kW, 2kW or 3kW. Generally speaking, more flexibility is better. In any case, in a room which was heatable (ie where you are heating a room and not one person in a warehouse) a convector heater is far preferable, as you get no noise at all.
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Bob Mannix
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Ah. A 3kW heater with 1kW and 2kW options would have no disadvantages over the 2kW one. Mine only has a half and full option. In any case, I was only playing devil's advocate. After all, I voted with my feet (should that be wallet?) and got a 3kW one.

Indeed. I quite like oil filled radiators for this as well. However, you can't beat a fan heater for emergency heat, as they are small and lightweight, so store more easily.
My new shed will have a convector heater, though, (on a frost stat and boost for when I'm in there). It will have 50mm Celotex/Kingspan and double glazing, too, ever since I found out the paltry cost of sealed units. I'm planning to store paint and decent tools in there and don't want them freezing/rusting.
Christian.
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I have a big, old draughty garage that couldn't possibly be heated. Tools are fine, if you give them a quick wipe over with WD40. Oil paints are fine but water based stuff just gets thrown away eventually. A heated shed eh?, there's posh. Better let them know on uk.rec.sheds. I'm sure they will have some OT comments to make.
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