Aluminum big wire anti oxidant

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I've had the privilege of working on an outdoor circuit panel box. The BIG aluminum stranded wires come into a 200 amp breaker. I can't see any hint of oxidation protection on the wire.
The building is about 100 feet from a lake, so it's humid. Should the big wire have some anti oxidant on it? Spray on laquer, or a blob of grey Noalox, or what? I will likely be at the building this Saturday, and concerned maybe I should put some oxidation protection on.
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Christopher A. Young
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Absolutely, and I prefer the grey antiox paste

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On Wed, 19 Mar 2008 00:22:27 -0400, "Stormin Mormon"

You really need to brush the wire before you put on the paste. Whether it actually does anything is something that is still up in the air. A properly torqued connection should be "gas tight". I have heard convincing arguments both ways.
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aluminum doesn't rust. It's oxide protects it.
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AZ Nomad wrote:

ALox is an electrical insulator. When AL electrical connections start to oxidize the electrical contact area decreases leading to overheating and sometimes total meltdown.
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That would be valid if the connection was never tightened. When it is tightened, the screw/clamp easily breaks through the film deep alox skin to the unoxidized aluminum. Once tightened, there is no oxygen at the connection.
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On Wed, 19 Mar 2008 16:56:20 -0000, AZ Nomad

Mr Lewis does have a valid point about the different metals and expansion rates. The biggest change in the CO/ALr device was selecting a better alloy for the screws (they use a special brass alloy instead of steel). These track the expansion rate of aluminum vitually identically so you don't break the gas tight seal. Most lugs are aluminum anyway so the expansion rate is the same. The goo is popular and some lug manufacturers "recommend" using it in the instructions but I have not seen one that says "shall" or "must" so it is noit a code issue. Wire manufacturers generally say it is not needed.
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Course it rusts. That's what aluminum oxide is. The difference is that the oxide forms a hard impervious coating that prevents further oxidation .... under many conditions, but not all. When exposed to electrical currents, salts, periodic dampness (with any trace of other minerals) will cause continuous erosion. As will physical abrasion, acidic environments, galvanic action etc.
When nicked or improperly clamped (especially in contact with dissimilar metals), heat cycling (expansion/contraction) + electricity will destroy connections.
Aluminum connections _MUST_ be coated with the proper anti-oxidant grease. Yes, it makes a difference. It's also required by the electrical code.
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Chris Lewis,

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On Wed, 19 Mar 2008 16:50:40 -0000, snipped-for-privacy@nortelnetworks.com (Chris Lewis) wrote:

Which article is that?
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I may have "overspoke" <grin> a bit.
I don't have NEC code at hand to check, and my copy of the CEC is about 20 years old, so I don't have the fine details.
That edition of CEC doesn't say a lot about aluminum, except being especially cautious about proper screw termination, no nicks, etc.
However: our municipality (City of Ottawa) forbids the use of aluminum in general purpose circuits. Only permits Al for large feeds (pony panels etc). Insists on anti-oxidant grease on all terminations. The inspector faulted my inspection because the electrician forgot it on the the garage subpanel feed. It was the only defect.
[Didn't flunk it, just made sure I had the electrician back to fix it.]
I assume it's province-wide, because those inspectors don't work for the city.
Many regions may consider the lack of it to violate the workmanship clause. Anybody else know if it's explicitly spelled out directly in the code?
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Chris Lewis,

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Chris Lewis wrote:

Hi, Also there are Al- Cu compatible components. My last house built in the mid-70' had Al wiring. Living there for ~20 years, never had any trouble.
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Certainly. So have I. On the other hand, virtually all the burnt out connections I've seen have been Al.
As there seems to be a general ban on using Al for general purpose circuitry these days here, you only get to use COALR devices in retrofits/renovations, or new large feeds. Not permitted for new construction GP circuits.
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wrote:

That is probably going to change with the skyrocketing cost for copper. Isn't the only reason it isn't permitted for GP circuits the fact that it requires outlets/switches designed for Al?
Even when Al was 4 times the cost of copper, it was more cost effective for high amperage feeds. Now that the cost of copper is 2-3 times that of aluminum, I think there's going to be a rebirth in the use of it aluminum for internal house wiring.
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That's what they thought 30 years ago. And 20. In other words, we've been here before -)

The burnt out connections were to Cu/Al (and possibly some CO/ALR) rated devices....
The reality is that while Al is perfectly safe (at least with CO/ALR devices done as per specification), it is considerably less forgiving of sloppy workmanship.
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Chris Lewis,

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wrote:

The difference is that copper was 1/10th the cost of aluminum 30 years ago. And 1/5th the cost of aluminum twenty years ago.
Nowadays, copper is 2-3 times the cost of aluminum.
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Should I go squirt a bunch of noalox on the connections at the church camp, in the disconnect box, near the water front?
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On Sat, 22 Mar 2008 20:54:48 -0400, "Stormin Mormon"

I thought Mormons didn't get drunk and post to usenet?
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Thanks, I'm glad you think that.
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Nope. Aluminum was cheaper than copper 34 years ago (when I wired my grandfather's cottage)[+].
Aluminum wire for residential circuits became common in the early-mid 70's for the very reason it was cheaper than copper _then_. They sure and hell wouldn't have used it _then_, and we wouldn't be going on about the hazards of Al _now_, if it was 5-10x copper pricing back then.
Al pricing is primarily determined by electricity costs. Whereas copper is more heavily influenced by supply/demand of the ore, which is getting somewhat harder to come by.
If you go here and compare both copper and aluminum, you'll see that both copper and aluminum have had more-or-less the same fluctuations in price over the past 15 years. Copper a teensy bit steeper. But both have approximately doubled over the past 15.
[+] Supplier: "Do you want aluminum or copper?" Me: "What's the difference?" Supplier: "Al is a bit cheaper, copper is a bit easier to work with" Me: "Grandpa, copper please?" GP: "Okay...."
40 years later, thank heavens.
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Chris Lewis,

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Whoops, sorry, left out the links:
http://www.infomine.com/Investment/HistoricalCharts/ShowCharts.asp?c=Copper http://www.infomine.com/Investment/HistoricalCharts/ShowCharts.asp?c=Aluminum
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