Aluminium wiring

[Steve T]

Hi all,
I'm helping a friend of mine do up an old cottage that he has bought recently. Most rooms are in such a state that they need completely redoing. Our first project was to rip out one of the bathrooms, and in doing so we had to disconnect an old infrared wall heater, where we discovered aluminium t&e. It's definitely PVC not rubber. I had a quick look in the ceiling rose in that bathroom and it also appears to be wired in aluminium t&e. We didn't look at anything else today so I don't know what other circuits may or may not have aluminium t&e.

The property has clearly had quite extensive electrical work over the years(has had an extension and loft conversion) as well as some diy bodges, as I suppose is to be expected. The CU is also not original, it looks like it should be a 16th edition split load but someone has replaced the main switch with an RCD. So clearly the CU has been changed at some point.

I'm definitely going to suggest he gets an EICR done, but do you think the aluminium t&e presents an immediate problem and should be rewired, or is it still OK to be in service?

Also if we have to work with the aluminium t&e at all (changing lights, sockets etc) how should we treat it? It's all stranded of course, so should we use ferrules on the ends and connect to screw terminals directly or into wagos and 'pigtails' in copper to the accessory?

I haven't got any pictures at the moment unfortunately but I am back at his house tomorrow so I can get some (of the CU, and anything else?)

Thanks!

 

[brianmoooore]

Are you sure it's aluminium, and not tinned copper?

 

[westward10]

If it is for lighting such as 1.5 then copperclad aluminium or plain aluminium is not likely to be stranded.

 

[Steve T]

If it is for lighting such as 1.5 then copperclad aluminium or plain aluminium is not likely to be stranded.

Yes it was definitely either 1.0 or 1.5 and was stranded, the CPC however was solid.

 

[brianmoooore]

Sounds like 3/029 to me. Aluminium will break very quickly if you flex it.

 

[Steve T]

Are you sure it's aluminium, and not tinned copper?

I haven't heard of that before but you may well be right. How can you tell which it is? It was reasonably flexible and didn't just snap when bent around so would that suggest tinned copper?

 

[brianmoooore]

See my last post!

 

[Robson689]

I haven't heard of that before but you may well be right. How can you tell which it is? It was reasonably flexible and didn't just snap when bent around so would that suggest tinned copper?

Scrape the strands with a knife

 

[Steve T]

Thanks for the replies so far, I will go back again tomorrow to try to figure out if it is actually tinned copper, and will also post some pics. But from your posts it seems most likely it is not aluminium as it didn't just break when flexed about. If its tinned copper are there any special considerations when working with it and how old is it likely to be?

 

[brianmoooore]

It'll be from the '60s if it's PVC, and should be as good as the day it was made if it hasn't been abused.

 

[Lucien Nunes]

The appearance of the conductors is quite different - aluminium looks duller, softer and greyer than tinned copper and is mechanically very weak. It indents and crushes under the tip of a screwdriver in a way that copper doesn't. As above, small aluminium cables are likely to be solid.

Imperial cables prior to metrication around 1970 were usually tinned copper and stranded (although the common 3/.029 lighting cable has a solid 1/.044 CPC.)

If its tinned copper are there any special considerations when working with it and how old is it likely to be?

No special considerations, it's just copper cable with a protective finish of tin to make it more corrosion resistant. Historically tinning was needed to prevent sulphur in rubber insulation reacting with the copper, but with PVC insulation it was something of a luxury and dropped in the transition to metric to save cost. It is still preferred for some applications.

Your cable is therefore likely to be 1960s if it is PVC insulated.

 

[telectrix]

mybet's on tinned copper. scrape or file to see.

 

[Sparky Pat]

Back in the depths of time my father used some aluminium cable when there was a copper shortage, and I have seen some but it was solid conductors not stranded.

 

[loz2754]

I pulled out a short length of aluminium twin and earth, PVC, from a job last week. Solid conductors, around 2.5mm csa. Tried the bend and snap - it snapped!

 

[telectrix]

we used to call it crocodile cable. 1 tug and it snapped.

 

[UNG]

I've come across very little aluminium t&e seen more alcumic and all aluminium mic and what a disaster that stuff was
EDIT just remembered had to terminate a large aluminium swa with double crimped lugs many years ago not something I'd want to repeat

 

[Simon47]

Back in the depths of time my father used some aluminium cable when there was a copper shortage, and I have seen some but it was solid conductors not stranded.

BT (or it was probably Post Office Telephones back then) went through a phase of using aluminium when copper was in shortage. It created decades of problems for them as the slightest water ingress turns aluminium cable into a plastic tube full of white powder.
Back in the 90s/00s, where I worked we had a site on the Isle of Wight and fell victim to this. In total we had about 9 pairs into the building, and no end of faults. Eventually BT ripped out the old ally cable (a trunk cable somewhere between the exchange and our site) causing all the faults, so while the site was completely offline for a few hours, we had no faults after that.

Still, dad had a tale of using silver for busbars during the war. He said they kept meticulous records of where, and it was all replaced with copper when it was available.

 

[DPG]

BT (or it was probably Post Office Telephones back then) went through a phase of using aluminium when copper was in shortage. It created decades of problems for them as the slightest water ingress turns aluminium cable into a plastic tube full of white powder.
Back in the 90s/00s, where I worked we had a site on the Isle of Wight and fell victim to this. In total we had about 9 pairs into the building, and no end of faults. Eventually BT ripped out the old ally cable (a trunk cable somewhere between the exchange and our site) causing all the faults, so while the site was completely offline for a few hours, we had no faults after that.

Still, dad had a tale of using silver for busbars during the war. He said they kept meticulous records of where, and it was all replaced with copper when it was available.

Some estates round here have the same problem with ally BT cables. Built late 70s/early 80s roughly.

 

[Steve T]

Update: so I went back and took a bit of the cable home with me. Here are some pictures:

As the pic shows the CPC is solid and both L&N are 3 strands.

I scraped at the wire with a knife and copper was revealed underneath the silver surface, so as lots of people suggested it appears to be tinned copper PVC t&e.
Thanks all for your help

 

[Steve T]

Also, picture of the consumer unit, it looks pretty butchered to me!

 

[UNG]

Most of the BT aluminium cable was installed in the mid to late 70's and most of the houses round where I live were built from about early 74 up to 78 / 79 and nearly all the trunk cabling into the area is aluminium, when they first introduced ADSL there were loads of problems getting anywhere near the speeds they claimed and a lot of it was down to the aluminium

 

[timhoward]

Also, picture of the consumer unit, it looks pretty butchered to me!

Circuit 4? B40 and apparently sockets.

 

[littlespark]

Most of the BT aluminium cable was installed in the mid to late 70's and most of the houses round where I live were built from about early 74 up to 78 / 79 and nearly all the trunk cabling into the area is aluminium, when they first introduced ADSL there were loads of problems getting anywhere near the speeds they claimed and a lot of it was down to the aluminium

I thought BT tried to introduce ISDN first before ADSL.....

My uni lecturer called it “It Still Does Nothing”

 

[UNG]

I thought BT tried to introduce ISDN first before ADSL.....

My uni lecturer called it “It Still Does Nothing”

BT had many different products around from the late eighties more suited to commercial enties communications needs and ISDN was on of them

 

[Rockingit]

I thought BT tried to introduce ISDN first before ADSL.....

My uni lecturer called it “It Still Does Nothing”

Indeed they did. And back in a time when I tried to escape from electrical work I had two 'banded' ISDN lines into my house, giving me a blistering..... 256K

 

[Simon47]

Alternatively, ISDN stood for I Smell Dollars Now
Another of those BT policies. In principle, it should have been a good option to nudge people towards ISDN - especially if they'd used the NTEs with built in analogue adapters. They could have had people on "digital to the premises", and with some additional diagnostics via the digital link. And for people wanting two lines (e.g. phone and fax - remember those ?), only one pair.
But no, they didn't want to risk damaging their leased lines cash cow - so ISDN was priced to avoid that risk, and it never really became a "mass" product.
They did the same thing with ADSL at first - deliberately priced to stop people ditching their leased lines. I recall back in the 90s we had two 64k leased lines - about 6k/year each IIRC. These days (or rather, at my last job) we just put in ADSL and run a VPN for something like 1/10 of the cost and higher bandwidth.

 

[Markyd]

If the house is in that bad a state as you mentioned rewire it anyway

 

[Zerax]

Still, dad had a tale of using silver for busbars during the war. He said they kept meticulous records of where, and it was all replaced with copper when it was available.

I seem to remember a story about when they were making the atomic bombs for Hiroshima etc... they needed to make large electro-magnets, for which you'd usually use copper of course. However it was wartime... copper was very scarce, but they had large reserves of silver in the state vaults... so they used that instead. Then after they'd finished with it... it was smelted back into ingots ! Perfect recycling !

 

[Zerax]

They did the same thing with ADSL at first - deliberately priced to stop people ditching their leased lines. I recall back in the 90s we had two 64k leased lines - about 6k/year each IIRC. These days (or rather, at my last job) we just put in ADSL and run a VPN for something like 1/10 of the cost and higher bandwidth.

I remember working for a Telco years ago when SDSL was just starting... we had a bunch of demo connections for sales purposes... and the speed increase was dramatic ! It was almost like science fiction to us...

 

[Simon47]

Yeah, and they managed to kill SDSL off as well. Would gave been ideal for a lot of business situations.

 

[pc1966]

If the house is in that bad a state as you mentioned rewire it anyway

Have to agree. If the cable quality, rating, or soundness of any connections is in doubt the best use for it is to pull new stuff through.

But step back and ask the question of what should the final installation look like? How many sockets per room and where?

Anything from that era will probably be sadly lacking and so starting from the desired outcome, instead of what is already there, is the best thing I could suggest.

 

[Steve T]

Have to agree. If the cable quality, rating, or soundness of any connections is in doubt the best use for it is to pull new stuff through.

But step back and ask the question of what should the final installation look like? How many sockets per room and where?

Anything from that era will probably be sadly lacking and so starting from the desired outcome, instead of what is already there, is the best thing I could suggest.

If it was my house I would certainly rewire it.

It does seem to have sufficient socket outlets but none look original so its safe to assume lots of additions have been made. Also the light and switch points don't have any CPCs, they have used junction boxes in the attic space and double insulated singles to the switches and lights. At least everything is fairly easily accessible.

I will certainly suggest a rewire to my friend as he is planning quite extensive work and I'm sure when he gets an EICR done that will at least suggest rewiring the lighting circuits as well as a new consumer unit etc.. But I'm sure you're all familiar with people who don't see a problem if it all 'works' so we will see what he decides to do!