incredible price of copper

Who said anything about differential? The thermal expansion of the aluminum against the screw, be it brass, aluminum, whatever, results in the "cold flow" phenomenon where the soft aluminum alloy flows out towards the unrestrained sides. When the connection cools and the aluminum contracts it is now a looser connection and the mating surfaces are more exposed to air and oxidation.

Aluminum oxide forms on the areas newly exposed due to the cold flow and with aluminum oxide being an insulator the remaining contact surface will be more heavily loaded and will heat more the next time the connection is loaded. The problem will rapidly accelerate until the connection fails completely, if you're lucky, not starting a fire in the process.

Pete C.

The wire isn't "bound tightly to the pole insulators" - the insulation is, and that's why the insulation could be stripped in this manner.

These weren't "high line" wires...

David, >

OK, we can probably go back and forth on this all day. My point about the line coming into your shop was that EVERY inch of wire on the poles owned by your public utility, strung along the highway, and up to your meter IS ALL aluminium. If you elected to string something else on your private run from the meter to your house or shop that was at your urging, but the standard for that run as well is aluminium. So if the problem was a flaw inherent with aluminium itself it wouldn't be used to string power lines. The problem is the connections, not the material. There are two possible solutions to fix the problem, 1) make proper connections, 2) use a more expensive and scarce material (copper) that is more tolerant of a poor connection.

Look, aluminium is used for residential wiring the world over, that is a fact. I don't deny that aluminium requires better connectors and more care or knowledge to do a safe wiring job, I am simply saying that it is a good product that works very well when properly installed and it's lack of use in the US is a combination of myth, politics, fear, and yes even some truth to the claims of it's shortcomings.

I would have no problem living in a home with aluminium wiring, I would simply want to know that the job was done correctly.....The same way that I expect a plumber to run a water line, or a machine shop to properly manufacture airplane parts, or grind the valves in my wifes car.

Kirk

One. Thermal expansion rates and self-extrusion or creep. Aluminum expands much more than Steel or Copper does when heated, as compared to Copper conductors in common lugs or Steel screws and backing plates in devices. Aluminum wire in Aluminum screw lugs isn't bad because they'll both expand, but you still have to bolt that lug to the busbars.

Two. Copper Oxides are almost as conductive as pure Copper, and that is a good thing. Aluminum Oxide is a very effective insulator, and that is a very bad thing. Try taking an ohmmeter reading on the barrel of your Maglite without scratching through the anodizing layer, anodizing is a controlled aluminum oxide deposition.

Three. You can Tin plate the Aluminum to mitigate a lot of the oxidation problems when you want to use it for switchboard busbars and breaker stab busses, and that's fine - but only as long as the Tin coating isn't disturbed. Pierce the Tin, and the corrosion and oxidation moves underneath and hits with a vengeance.

Add Problem One and Problem Two together, and you have the cause of most Aluminum Conductor failures, and the few fires that occur if the symptoms of a bad connection are ignored for too long.

You put a full 20A load on the receptacle, the connection gets hot, the wire expands under the screw and extrudes itself out a bit. After a while, air starts getting under the screw, the wire starts to develop an aluminum oxide layer under the screw head and the connection resistance goes up.

With the higher resistance connection the next time you put a full

20A Load on the wire it gets much hotter, and arcs a little between the wire and screw which speeds the heating even more. The oxide layer gets deeper, the resistance gets higher...

It is a feedback loop. And the end result is the wire and the screw lug get hotter than the space heater you are trying to run from it. Cue the Fire Department...

FACT: They can not make an inexpensive effective and safe branch wiring device for using Aluminum branch circuit conductors.

FACT: You could use compression lugs, but they have to be done properly, and that's where that plan falls apart.

FACT: There are a surprising number of people out there who have their shingle hung out as an Electrician who DO NOT THINK. They are physically incapable of coherent thought. Just figuring out which end of the screwdriver to pick up was a major accomplishment...

They throw out the instruction sheet that says how the connections must be done and the steps tools and materials required, they do it the way /they/ think it should be done - and if the inspector doesn't catch it and make them redo the work, those are the connections that are going to fail in 10 years.

They could make a foolproof Aluminum-wire-safe convenience receptacle or light switch, but they would be very expensive - meaning nobody would buy them. And they would likely be designed for one-time-use - meaning someone will figure out how to reuse them to save money, ignoring the safety aspects.

Fact: Copper branch circuit wiring isn't cheap, but it can (and often is) installed by clueless induhviduals without too many safety repercussions.

Conclusion: Aluminum is fine for feeder conductors, but should be in compression connectors or compression pin transitions at both ends. (And if not possible, there should be a generous slack loop available at both ends for the inevitable reterminations.)

Any existing Aluminum branch circuits should be reterminated in special crimp connectors, or repull the whole house to be sure - there's always one odd box in the attic or crawl space they missed...

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"1968fj40" wrote in news:1157687244.608437.79460 @d34g2000cwd.googlegroups.com:

And THAT, right there, is the whole problem: as others have stated, most electrical wiring is done "under the supervision of a licensed electrician" - NOT "BY a licensed electrician".

When Pedro de Mexico or Hung Chow from Canton or Mustafa Glang from Bangladesh is busy stringing and terminating the wiring, the "licensed electrician" is back at the office with his feet on his desk and the "foreman" is down at Duncan Donuts having coffee.

Since the "Inspector" is a v-e-r-y g-o-o-d friend of the "licensed electrician", he'll only drop by the site long enough to see that the workers have loaded their toolboxes back in the truck and then sign off on the job.

I'm glad you'd be happy living in a home with Aluminum wiring - I won't knowingly walk into one: I've fought too many fires caused by the stuff and have no desire to do so ever again.

Incorrect. The main transmission lines are pretty much all ACSR which is aluminum clad steel reinforced wire for the long spans. A good deal of the secondary distribution lines are indeed copper.

The issues are not the same when aluminum is used for primary lines that are also exposed to free air cooling. The much higher voltages can easily punch through developing aluminum oxide layers that would readily insulate at 120V. The free air cooling reduces the heating and cold flow issues as well.

As noted, there is not a valid comparison between residential use of AL branch circuit wiring and utility use of AL wiring on primary circuits.

Considering the number of licensed electricians in the US who have trouble even keeping to code with copper wire, a reintroduction of AL wire for small branch circuits would be a disaster. Those marginally qualified yet licensed electricians are also more likely to be doing residential work since commercial outfits won't hire them.

A house with AL wiring would not automatically be a deal breaker for me if the house was otherwise appealing. I would however require a closing credit to cover the material cost of replacing the AL wiring.

When I took possession of the house and before applying any electrical loads beyond a couple lights, I would go through the place checking every single device and connection to insure they have proper AL rated devices, have anti-ox compound and are properly tightened. I expect this process would take me a long weekend day to complete.

At that point having inspected all devices and connections and corrected as needed I would know things should be pretty safe for at least a few years. I would then proceed to replace the AL wired circuits with copper as I had time and in coordination with any remodeling I might do.

Pete C.

My point about

The service line from the utility coming into one of my homes is all copper.... it's my summer home in the mountains, not at all unknow in these parts pure copper wire. It was build to service some hard rock mines., 3 phase.

There's also a birds nest of this copper wire buldozed into a pile that must weigh a good amount from part of old line...... has to be from the day when copper scrap was not worth much. After reading this thread I went up last night and had a look ..the wire is mostly green no insulation many K feet 8 ga. real tangled mess.

ED

I'm going to call "Bullshit" on this one, too. The insulation is molded onto the wire at the factory, it isn't slid inside like a garden hose. And they lash the wire to the insulators rather securely just to take the strain of keeping it up there - at the ends it's mechanically anchored to the insulators with U-bolts and 'Chinese Finger' strand grips, the tighter it gets the stronger the hold.

Now if this guy was pulling UNDERGROUND feeder wires WITH the insulation out of the conduits, and then reeling it into the truck when it was clear, that is plausible.

(In other words: Dear OP, Send that Urban Legend back to your "Friend Of A Friend" for a Rewrite...)

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I do my own work. Only way to guarantee to my satisfaction that it is done correctly.

Pete C.

A connector that provides spring pressure below the force required for the cold flow will absorb the expansion and return maintaining pressure after the AL cools.

I don't have any AL here at all. No 14ga copper either, everything is

12ga or above. I did just replace the main panel, the shop sub panel, shop feeder and a number of outlets in the kitchen and baths (to GFCI and Decora style) so a good number of the connections have been recently serviced.

Connectors are always the largest issue in anything, be it high voltage, low voltage, AC, DC, plumbing, structural, etc. An unbroken length of anything is more reliable than a broken and reconnected one.

With current sprawl the issue is diminishing as many subject homes are demolished to make room for more sprawl.

Or when industry lobbyists push for a change to promote their product under the cover of potentially saving lives.

Not when the houses are being torn down and replaced with McMansions, apartment complexes and office parks.

Hopefully insured and no fatalities.

Pete C.

You are very likely living in a house with aluminum wiring. Not for the branch circuits, but for the clothes dryer, electric stove, and from the meter to the breaker box. I know my house has aluminum wire in those circuits. And they have been trouble free for over thirty years.

Now if Bruce Bergman reads this..........Could you comment >

Well I sure as hell wouldn't, for that reason right there.

I had a plumber that couldn't put in a water pump so it wouldn't leak.

I had a half dozen car dealership mechanics unable to fix the ABS on my Camaro.

I had the bike shop unable to properly reassemble the fairing on my DL-650. I've also seen them unable to properly check the valve clearances on my SV-650. They also put a tire on backwards, then had the gall to say "who put that on?" YOU did, moron. Hell, they can't even balance a tire properly.

I've had the dumbass running the firewall at work close port 25 and wonder why email stopped working.

In short, I haven't had ONE person work on ANYTHING and do it RIGHT without me either supervising or having to come back and BEAT ASS multiple times.

Around here, common sense is not an option.

-gc

Bruce L. Bergman wrote in news: snipped-for-privacy@4ax.com:

Not NOW it isn't.

A lot of the wire installed in the Texas Panhandle during the late '30s and the '40s WAS.

You must have missed the time frame, Bruce!

It's normal practice to check the main lug torque and give a visual check for burned wiring and deterioration every time you are in a panel. Catches a lot of developing problems before they get critical.

That's more a factor of ambient temperature than copper conductor failure - the wiring chamber gets too hot, and the lugs heading to the heating elements get it the worst. Putting Noalox there isn't going to accomplish anything

The only thing you can do in those cases is make sure that the crimp lugs on the element studs are the special "High Temperature" ones - Nickel alloy. And be sure to use a Copper or Nickel based anti-seize compound on all studs and screws so they come apart later.

And you want to use "Nickel Hinge Wire" for interior hookups - Nickel alloy wire with silicone insulation and fiberglass overbraid.

If you can, punch some cooling louvers in the control can. And better yet add a small fan. Even dropping the control section interior 100F can have big benefits.

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" snipped-for-privacy@krl.org" wrote in news: snipped-for-privacy@i3g2000cwc.googlegroups.com:

Not a chance: this house was built in 1948 - long before they started marketing jacked Aluminum wiring - and none has ever been used inside it.

Even when I had the garage/shop rewired no Al wire went in. [I not only looked later, I was there while the work was being done - an advantage of retirement - and even collected the scraps.]

BTW, SWMBO has a Gas Central Heating system, a GAS stove, a GAS dryer, and a GAS hot water heater - not electric. [The electric bill for the Air Conditioning and my shop is quite high enough, thank you!]

ED wrote in news: snipped-for-privacy@4ax.com:

Take a b-i-g pair of bolt cutters with you on your next visit to the pile!

If it's dumped? Hell yes. Probably won't get "clean copper" price but even at say 2 bucks a pound? Hell yes.

Imagine a tanged mess of wire from a pole going down into a river and floating downstream pulling wire with it. It's been there long enough for trees to grow up through it.. The smallest bolt cutters work perfectly. I need to shop it around for the best price. I wonder what explaining will be needed to sell 5 gal buckets of old copper wire..

ED