Aluminium wiring

Steve T · May 22, 2021

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 · May 22, 2021

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

westward10 · May 22, 2021

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

Steve T · May 22, 2021

westward10 said:
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 · May 22, 2021

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

Steve T · May 22, 2021

brianmoooore said:
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 · May 22, 2021

See my last post!

Robson689 · May 22, 2021

Steve T said:
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 · May 22, 2021

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 · May 22, 2021

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 · May 22, 2021

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 · May 23, 2021

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

Sparky Pat · May 23, 2021

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 · May 23, 2021

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 · May 23, 2021

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

UNG · May 23, 2021

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 · May 23, 2021

Sparky Pat said:
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 · May 23, 2021

Simon47 said:
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 · May 23, 2021

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

[ElectriciansForums.net] Aluminium wiring

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 · May 23, 2021

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

UNG · May 23, 2021

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 · May 23, 2021

Steve T said:
Also, picture of the consumer unit, it looks pretty butchered to me!

Circuit 4? B40 and apparently sockets.

littlespark · May 24, 2021

UNG said:
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 · May 24, 2021

littlespark said:
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 · May 24, 2021

littlespark said:
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

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