Aluminum big wire anti oxidant

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.

Reply to
Stormin Mormon
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Absolutely, and I prefer the grey antiox paste

Reply to
RBM

aluminum doesn't rust. It's oxide protects it.

Reply to
AZ Nomad

ALox is an electrical insulator. When AL electrical connections start to oxidize the electrical contact area decreases leading to overheating and sometimes total meltdown.

Reply to
Pete C.

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.

Reply to
gfretwell

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.

Reply to
Chris Lewis

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.

Reply to
AZ Nomad

Which article is that?

Reply to
gfretwell

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.

Reply to
gfretwell

According to :

I may have "overspoke" 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?

Reply to
Chris Lewis

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.

Reply to
Tony Hwang

According to Tony Hwang :

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.

Reply to
Chris Lewis

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.

Reply to
AZ Nomad

I think most people have similar experiences. Al problems were usually traced to workmanship problems and the houses that were going to have problems had them. There are still millions of aluminum wired homes that have never had a problem. The new alloy and CO/ALr devices would perform as well as copper but the reputation is still out there. There is no NEC reason why you could not wire an aluminum house today. In fact ALCAN is trying to rehibilitate the aluminum reputation in presentations to inspectors and contractors as we speak. I doubt it is going to work out for them.

Reply to
gfretwell

. I believe in the US, antioxide paste is only required if the manufacturer requires it. But all the electricians I remember used it.

For 15 & 20A branch circuits wired with aluminum around the 1960s, a recommended procedure for making connections, based on extensive tests, includes abrading the aluminum surface and using antioxide paste.

Reply to
bud--

Not to be a nit-pic, but aluminum does rust. The color of the rust is white (aluminum oxide), unlike iron oxide which is reddish brown. Aluminum will pit, especially if exposed to acids.

Reply to
Phisherman

Oh, for christ's sake. Are you nitpicking just for the sake of nitpicking?

Take some iron. Stick it in a tub of water. Do the same with aluminum. Wait a year.

Tell me again how aluminum rusts. The iron will pretty much disolve. The aluminum will develop a film and then do nothing.

And how the f*ck would acids get into an electrical panel?

Reply to
AZ Nomad

yes, always

Reply to
Chris Miller

I can confirm alunimum does rust, turns into white dust.......

much worse with moisture around like in a basement.........

saw a thomas edison invention at the museum in detroit literally falling apart. it was sad

Reply to
hallerb

Extensive testing done for the Consumer Product Safety Commission showed properly made aluminum connections failed.

The new alloy wire and CO/ALR devices eliminate expansion problems, but oxide problems remain. With large wire, the wire is deformed when tightening lugs, which breaks the very thin aluminum oxide insulating layer. With 15 & 20A branch circuit devices the oxide can substantially remain intact.

For its lugs Ilsco recommends (?requires) the wire be wire brushed to remove oxide then an antioxide paste used. The equivalent is not likely to be done with small branch circuit wiring.

CPSC testing found a wire nut connection could develop minimal wire-to-wire contact (insulated by the oxide) with most of the current through the spring in the wirenut. The spring is not intended as the conducting path and could get red hot. (No arc at this stage so the new AFCIs won't trip.)

The CPSC estimated the old technology aluminum was 55 times as likely to reach "fire hazard conditions" compared to copper - an increased risk, not a certainty. The new technology should be a lot safer, but I suspect consumers won't want it and a lot of contractors won't want to install it - your bottom line.

Reply to
bud--

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