Aluminium vs. Copper Wire

On 1/10/2022 7:41 PM, whit3rd wrote:
> On Monday, January 10, 2022 at 12:20:45 PM UTC-8, gnuarm.del...@gmail.com wrote:
> 
>> Aluminum and copper coated aluminum were used widely in the 70s in the US. Many of them caused fires because they were not installed correctly. In the 90s there were many services which would crimp (properly) copper ends onto the aluminum wires so they could be used with conventional devices without risk of fire. I don't hear about this so much anymore.
> 
> Large-gage wires are almost always aluminum (500 mcm and up), and are terminated in
> hydraulic swaged copper-alloy lugs with a paste that prevents corrosion/degradation of the
> joints.   It has been used extensively for many decades, but is  not often found in house wiring
> because of its past problems, and building code restrictions.
> 
> Proper techniques are  older than the 90s, I wired a bakery in the early 70s that used
> acceptable oxygen-free aluminum terminations.
> 

My comments are for aluminum wire used in power wiring. Ed's #20 wire 
certainly isn't.

Aluminum wire is very common in larger sizes, including services for 
200A and larger, gauge 1/0, and is not a problem.

Problems were for 15 and 20A branch circuits, #12 and 10. About 1965 
copper prices spiked and aluminum started to be used in large quantities 
for 15 and 20A circuits. Problems ensued, like fires, and about 1971 UL 
removed the listing for aluminum wire and the aluminum rating for 
devices like switches, receptacles and wirenuts. New standards came out 
and the new switches and receptacles are marked CO/ALR. The new wire is 
harder, but the expansion is about the same. The vast majority of 
installed wire is the "old technology" stuff. UL tests are done with 
"new technology" wire, which is not what is mostly in the field. Use 
died out about 1973.

Aluminum wire has 2 major problems. One is high expansion rate. If it 
expands faster when loaded than the connection around it the wire can 
extrude making the connection looser on the next heat cycle. CO/ALR 
devices have better expansion characteristics, and harder wire helps.

The second problem is that aluminum is quite reactive, and a "clean" 
surface rapidly oxidizes. The oxide is very thin, but is an insulator. A 
wire nut may fail by oxide preventing wire-to-wire contact and the 
contact is through the cone shaped spring. A couple turns of the spring 
can become red hot. One fix is to abrade the wire to remove the oxide 
and apply an anti-oxide paste (like Noalox).
AlumiConn connections are rated for aluminum (and copper) and appear to 
be good. Likely that crews dig through oxide.
<http://www.kinginnovation.com/products/electrical-products/alumiconn/>
I think these are like UK chock-a-block (sp?).

Large wires have a screw that cuts through the oxide, and installation 
often abrades and uses anti-oxide paste. Also connection may be made 
with barrel connections that are radially compressed onto the wire to 
form a cold weld. There was a COPALUM fix for small wires that did the same.

The CPSE contracted to have extensive testing (thousands of connections) 
of aluminum connections. The results are at:
<http://www.kinginnovation.com/pdfs/ReducingFire070706.pdf>
The CPSC appeared to be headed for a recall. which would have been very 
expensive. In the inevitable court case aluminum wire was determined to 
not be a "consumer product" and thus not under the purview of the CPSC.

bud-- <null@void.com> wrote in
news:pJ7DJ.282003$aF1.232226@fx98.iad: 

> On 1/10/2022 7:41 PM, whit3rd wrote:
>> On Monday, January 10, 2022 at 12:20:45 PM UTC-8,
>> gnuarm.del...@gmail.com wrote: 
>> 
>>> Aluminum and copper coated aluminum were used widely in the 70s
>>> in the US. Many of them caused fires because they were not
>>> installed correctly. In the 90s there were many services which
>>> would crimp (properly) copper ends onto the aluminum wires so
>>> they could be used with conventional devices without risk of
>>> fire. I don't hear about this so much anymore. 
>> 
>> Large-gage wires are almost always aluminum (500 mcm and up), and
>> are terminated in hydraulic swaged copper-alloy lugs with a paste
>> that prevents corrosion/degradation of the joints.   It has been
>> used extensively for many decades, but is  not often found in
>> house wiring because of its past problems, and building code
>> restrictions. 
>> 
>> Proper techniques are  older than the 90s, I wired a bakery in
>> the early 70s that used acceptable oxygen-free aluminum
>> terminations. 
>> 
> 
> My comments are for aluminum wire used in power wiring. Ed's #20
> wire certainly isn't.
> 
> Aluminum wire is very common in larger sizes, including services
> for 200A and larger, gauge 1/0, and is not a problem.
> 
> Problems were for 15 and 20A branch circuits, #12 and 10. About
> 1965 copper prices spiked and aluminum started to be used in large
> quantities for 15 and 20A circuits. Problems ensued, like fires,
> and about 1971 UL removed the listing for aluminum wire and the
> aluminum rating for devices like switches, receptacles and
> wirenuts. New standards came out and the new switches and
> receptacles are marked CO/ALR. The new wire is harder, but the
> expansion is about the same. The vast majority of installed wire
> is the "old technology" stuff. UL tests are done with "new
> technology" wire, which is not what is mostly in the field. Use 
> died out about 1973.
> 
> Aluminum wire has 2 major problems. One is high expansion rate. If
> it expands faster when loaded than the connection around it the
> wire can extrude making the connection looser on the next heat
> cycle. CO/ALR devices have better expansion characteristics, and
> harder wire helps. 
> 
> The second problem is that aluminum is quite reactive, and a
> "clean" surface rapidly oxidizes. The oxide is very thin, but is
> an insulator. A wire nut may fail by oxide preventing wire-to-wire
> contact and the contact is through the cone shaped spring. A
> couple turns of the spring can become red hot. One fix is to
> abrade the wire to remove the oxide and apply an anti-oxide paste
> (like Noalox). AlumiConn connections are rated for aluminum (and
> copper) and appear to be good. Likely that crews dig through
> oxide. 
> <http://www.kinginnovation.com/products/electrical-products/alumico
> nn/> I think these are like UK chock-a-block (sp?).
> 
> Large wires have a screw that cuts through the oxide, and
> installation often abrades and uses anti-oxide paste. Also
> connection may be made with barrel connections that are radially
> compressed onto the wire to form a cold weld. There was a COPALUM
> fix for small wires that did the same. 
> 
> The CPSE contracted to have extensive testing (thousands of
> connections) of aluminum connections. The results are at:
> <http://www.kinginnovation.com/pdfs/ReducingFire070706.pdf>
> The CPSC appeared to be headed for a recall. which would have been
> very expensive. In the inevitable court case aluminum wire was
> determined to not be a "consumer product" and thus not under the
> purview of the CPSC. 
> 

 Originally they declared that the deadly Beverly Hill Supper Club 
fire in Northern Kentucky was the result of faulty Aluminum wiring.  
It was later determined that such was not the case.  In this 
instance.

  Without anti-oxidant applied heavily, I would not use AL wiring.
And would prefer copper.

  Oh and I have wired up some pretty heavy duty industrial control 
panels and they ALL use copper, even on the feed lines.  We are 
talking about some pretty big conductors and everything in 3 phase 
and cabinets over 8 feet tall and 18 feet long.

  And a myriad of smaller cabinets with a lot of #8 in them.  Again, 
all copper.

On a sunny day (Mon, 10 Jan 2022 12:05:19 -0800) it happened John Larkin
<jlarkin@highland_atwork_technology.com> wrote in
<bu3ptg12tqvo4n6bclku4bmcjdp4unpf40@4ax.com>:

>On Mon, 10 Jan 2022 19:05:00 -0000 (UTC), Cydrome Leader
><presence@MUNGEpanix.com> wrote:
>
>>Ed Lee <edward.ming.lee@gmail.com> wrote:
>>> I got some Aluminium wire by mistake.  It's difficult to solder.  Perhaps it's made for crimp connectors.  In the long run,
>>> do Aluminium wire break easier than Copper wire?
>>
>>What type of wire and guage? Al can be crimped with the proper tooling 
>>like with solid wire crimps and dies, not the stuff you just crush with 
>>the plier looking tooling. I'd still use a deoxit type grease.
>>
>>Soldering Al is a weird process, needs lots of scraping and a zinc bearing 
>>solder. No flux is needed.
>
>Copper wire is pretty good copper. Aluminum is sold as alloys, some
>with rotten electrical conductivity. Numbers like 4:1 worse than pure
>copper.

I have seen a documentary about how that big A380 airplane is build.
It says to save weight much of the wiring is alu.
Must be reliable somehow :-)

On 10/01/2022 20:05, John Larkin wrote:
> On Mon, 10 Jan 2022 19:05:00 -0000 (UTC), Cydrome Leader
> <presence@MUNGEpanix.com> wrote:
> 
>> Ed Lee <edward.ming.lee@gmail.com> wrote:
>>> I got some Aluminium wire by mistake.  It's difficult to solder.  Perhaps it's made for crimp connectors.  In the long run, do Aluminium wire break easier than Copper wire?
>>
>> What type of wire and guage? Al can be crimped with the proper tooling
>> like with solid wire crimps and dies, not the stuff you just crush with
>> the plier looking tooling. I'd still use a deoxit type grease.
>>
>> Soldering Al is a weird process, needs lots of scraping and a zinc bearing
>> solder. No flux is needed.
> 
> Copper wire is pretty good copper. Aluminum is sold as alloys, some
> with rotten electrical conductivity. Numbers like 4:1 worse than pure
> copper.

What really hurts are the copper to aluminium joints however they are 
done. Power companies seem to manage it OK with big thick conductors but 
small signal stuff is skating on very thin ice.

Crimp joints on UK telcoms circuits from a particularly era when they 
briefly used cheaper aluminium cable cause a lot of trouble these days 
by partially rectifying ADSL broadband signals. BT management won't even 
admit to there still being any places afflicted with this problem.

https://community.bt.com/t5/Archive-Staging/aluminium-cable/td-p/1684522
https://www.quora.com/Does-BT-Openreach-still-use-lead-aluminium-cables

Big problem with aluminium is the inert oxide surface layer. Fluxes that 
break through it can cause serious trouble and a solder formulation to 
wet out both is possible but I wouldn't want to rely on it.

Aluminium wire is of most use to flower arrangers.

A village close to me has a mix of copper and aluminium wiring between 
them and the exchange. A few lucky ones got 1Mbps but 256kbps was more 
typical. They were one of the first to start peer to peer microwave 
links as an alternative to their virtually useless landline services.

-- 
Regards,
Martin Brown