70s house, aluminium conductors

[Pretty Mouth]

I visited a client about a week ago, an elderly couple complaining that their lounge, hall and landing lights were all flickering simultaneously with a noticeable buzzing noise. When I arrived the lights appeared to be working ok (I asked them to switch them off until I could attend), so an intermittent fault. Opening up accessories revealed the likely culprit - aluminium conductors, the first time I have come across these.

Some observations:
House built 1973
1mm² (or so I believe, next time I'll measure w/ micrometer) single solid strands
Dull silver appearance, brighter when cut.
Not copper clad aluminium, not tinned copper.
Very soft and supple compared to copper.
Higher resistance values vs copper
Prone to breaking off where screwed at the terminations.
It was hard to get a clean reading by testing continuity with the probe placed directly on the bare conductors (CPCs were unsheathed), the reading would jump around constantly in the range of a couple of ohms. I presume this is due to the insulating oxide layer aluminium is said to form. Clipping a jump lead to the conductor and testing to that gave a steady reading, as did testing to the brass terminal where soundly terminated.
Other circuits in the house are, at a glance, aluminium also.

I did what I could in the time I had available - I went through the circuit (downstairs lights) checking and tightening everything, found several conductors broken or very nearly broken at the screws so reterminated those, and ended up with satisfactory R1+R2 vs RN+R2 results. Borrowed neutral on landing light as you would expect for a property of that age.

Anyway, received another call from them on Christmas eve, they had noticed a small flash and pop! from one of the bedroom wall lights when switched on. Also switching on say the main bedroom light would cause a momentary flicker on the landing lights. He also told me they had an intermittent problem in the past with the bathroom light flickering, and certain sockets sparking when switched on. Advised not to use dodgy lights and sockets until I can get to them in a day or 2.

The place is obviously due a rewire, and that's what I will recommend. In the meantime, I'll need to make good any problems. I understand standard accessories are not to be used with aluminium conductors. Apparently some Wagos can be used on aluminium conductors when used in conjunction with the Alu-plus paste:

Syringe (249-130) | WAGO GB

Syringe; Contents: 20 ml Alu-Plus contact paste (4017332133890) Online at WAGO GB!

www.wago.com

I was thinking of using this to connect a length of copper conductor to the ends of the aluminium conductors, then terminating the copper in the accessories. I have reservations though, I suspect the 1mm² aluminium will be too soft and bendy to force into a wago 773.

What have other members of the forum done in these circumstances and what would you recommend? As always, all information gratefully received

 

[ipf]

I can't remember any aluminium conductors so small in domestic.
Have you thought of ferrules for the terminations....a little substance to make them a bit more stable for the time being.

 

[Pretty Mouth]

I can't remember any aluminium conductors so small in domestic.
Have you thought of ferrules for the terminations....a little substance to make them a bit more stable for the time being.

Good idea, ferrules would give them a bit of back-bone wouldn't they.

Yes, I'm wondering if they ever complied. I have a copy of 14th ed amended to 1976, there's a table of copper clad aluminium down to 1.5mm² but for plain aluminium, minimum is 16mm². I suppose it could have been different in previous amendments though.

 

[Pete999]

Are the accessories, modern types? because if My memory serves me well, there was a Copper shortage back in the day and I seem to remember that the accessories, had to be redesigned to accept Aluminium conductors, I may be mistaken as it was back in my youth, and memories dull with the passing of time, may be some of the other old timers with a better memory, will clear things up.
The American Electricians do use some sort of gunk when they terminate Al conductors.

 

[Pretty Mouth]

Are the accessories, modern types? because if My memory serves me well, there was a Copper shortage back in the day and I seem to remember that the accessories, had to be redesigned to accept Aluminium conductors, I may be mistaken as it was back in my youth, and memories dull with the passing of time may be some of the other old timers with a better memory will clear things up.
The American Electricians do use some sort of gunk when they terminate Al conductors.

I read that somewhere else too Pete. I'd say the hall and landing ceiling roses are probably original to the house, but switches have been replaced at some time or another, and the ceiling lights in the lounge are modern metal ones. You think the incompatible accessories are likely what's causing the issues?

The consumer unit was changed 2 or 3 years back. No mention of aluminium on the pre-change EICR, also no EIC or notification of the change. NICEIC approved contractor. I wonder if the MCB terminals are suitable for aluminium?

 

[Pete999]

I read that somewhere else too Pete. I'd say the hall and landing ceiling roses are probably original to the house, but switches have been replaced at some time or another, and the ceiling lights in the lounge are modern metal ones. You think the incompatible accessories are likely what's causing the issues?

The consumer unit was changed 2 or 3 years back. No mention of aluminium on the pre-change EICR, also no EIC or notification of the change. NICEIC approved contractor. I wonder if the MCB terminals are suitable for aluminium?

If they have clamp type terminal they may be OK, it's the screw type that do the damage to Al conductors. my only memory is that Judas Escariot played in goal for Bethlehem Hotspurs.

 

[Pretty Mouth]

If they have clamp type terminal they may be OK, it's the screw type that do the damage to Al conductors.

Accessories are definitely screw type, all of them, even the old ceiling roses. Hager MCBs IIRC, so clamp type.

 

[Pete999]

Accessories are definitely screw type, all of them, even the old ceiling roses. Hager MCBs IIRC, so clamp type.

Yes Mate they will be better than screw type, still if that doesn't work, good for you but not your customer maybe a rewire is called for. Of course stripping Alum conductors with Side cutters wont help either, care needed to be taken so speed wasn't an issue, speed leads to errors and poor workmanship in most case.

 

[freddo]

I've never known aluminium cables that small, even the lighting cables all seem to have a much larger CSA than the copper equivalent. Best to rewire if you can, all the stuff I've come across has been very brittle, and broke off with very little amounts of bending.

 

[littlespark]

Maybe a regional thing.
My parents house was built in ‘73 and it’s copper twin and earth, but the old stuff.
Ex council.

Have worked in old properties with VIR, but the insulation gave up well before the cable itself

 

[freddo]

The conductors should probably be coated with an anti-oxidant paste designed for aluminium electrical terminations. I use Ideal Noalox, though it's usually on much larger conductors.

 

[Pretty Mouth]

I've never known aluminium cables that small, even the lighting cables all seem to have a much larger CSA than the copper equivalent. Best to rewire if you can, all the stuff I've come across has been very brittle, and broke off with very little amounts of bending.

It seems to be very unusual. I've done a fair bit of online research into it the last few days and can only find 1 or 2 accounts of people having come across it at 1mm². I've just ordered some of the Wago Alu-Plus paste that I linked to in my OP, which I assume is much the same as Noalox - I'll report back here when I use it.

I'll be going there tomorrow to have another look at it so I'll get some photos, and take a measurement with the micrometer for those interested.

 

[davesparks]

Clean the conductor at the temrinations and apply anti-oxidant grease to the clean conductor. This can then be terminated into brass terminals.

As far as I know vaseline can be used in place of fancy anti-oxidant grease the same as you would use it on copper terminations.

The problem with aluminium conductors in brass terminals is that the dissimilar metals react and corrode.

 

[Robson689]

Might be worth getting some "paste" as we call it? Thomas & Betts CTB8 is the one we use at my work

 

[EddieSparks]

When you think about it, that wiring is almost 50 years old, it would not be unreasonable to suggest a rewire. The last thing you want to happen is start trying correct minor faults within the installation and making the problems worse by creating high resistance joints by damaging old terminals or even fracturing the conductors. Sometimes you can spend as much time trying to correct faults as it would take to rewire the circuit.

 

[davesparks]

When you think about it, that wiring is almost 50 years old, it would not be unreasonable to suggest a rewire.

As it is old aluminium wiring which has been known to fracture at bends or otherwise deteriorate then I agree, a rewire should be considered.
However if this was copper wiring I wouldn't be so sure, being 50 years old on its own wouldn't be reason enough to rewire.

 

[EddieSparks]

Totally, if the reading are good, then why replace it,

 

[davesparks]

Totally, if the reading are good, then why replace it,

That's not quite what I said, there's more to consider than just readings, tests only tell you a small part of the story. I find too much faith is put in the idea that passing a test makes everything safe, a twist and tape joint will generally pass testing.

I said being 50 years old on its own isn't a reason to rewire.

 

[EddieSparks]

But that is impossible to ever know how a circuit is constructed. But after 50 years of being in a house, and having people add to the circuit and take away parts. Which I Would put money on it that people have played around with it, you can’t go around ripping up the floor in someone house to have a look, so you have to go on something and you go by what the reading tell you. If the reading are clear, let’s say above 20Meg for example. Your R1/R2 are correct, other than looking at as much as you can see, That’s about it.
[automerge]1577392865[/automerge]
You are correct in saying age is not something to go by.

 

[Pretty Mouth]

I agree that a rewire would be for the best, hopefully they can afford it. As it stands I cannot say for certain that it has ever complied with the regulations, and I can find no data for current carrying capacity. Does anyone know if aluminium conductors would have the same CCC as copper clad aluminium conductors?