Aluminum Wiring Question

Care to cite a reference for all of that Mr. Know-it-all gibberish? That's ok, I'll do it for you:

On Mon, 03 Nov 2003 02:50:13 GMT, "Nukie Poo" Gave us:

Gibberish? Fuck you. I know more about metals, joining metals, and binding metals together than you ever will. No matter where you look.

Translated that means: "no, I won't post any references because I don't have nor need any. I just made it all up. But that's good enough because I know everything, your reference - or any other you may find - notwithstanding."

Your true colors shine through as always! What a pathetic closed-minded ignorant individual you are. I think I'll go now and leave some dark matter in my toilet.

Politely put, it and the paper it was written from, have some really basic problems - not much in the line of metallurgical expertise, contact degradation, or micro analysis. It does, however, have some pictures which reinforce the basic theory - not theirs - the real one.

background on the paper and its position -

If the author of the paper wants to discuss it, anytime. IMHO, he brings to the table observations but since he did not include any required basis in his paper, he must have lacked the foundation to correctly interpret those observations.

And the call for emery, if you know what emery is, basic abrasion engineering, and the mechanics of the use of emery on aluminum, is absolutely stupid. Note, however, that the author of the paper did not call for emery (excerpt of his suggestion in its entirety below).

As to the whining in the referenced paper about 20 years, 20 years, 20 years

- methinks he doth protest too much - especially since he presents no basis for his procedure other than he saw some events, he found a procedure that has one redeeming step in its ten steps that worked for a year, and he wants to sell it to NYS.

As to my credentials vs credentials for the man who put his thoughts down on dead wood - I think I can hold my own. ME, EE, PE licensed in NYS (no less). Design, Forensic, and Safety engineering for around 30 years, degreed after six years of military test facility lead and civilian tech work on rather sensitive and powerful equipment. Been on ANSI, UL, and OSHA committees reviewing this stuff for about

25 years. Certifed as expert in the field in a fair number of state courts and federal court. And best - I have certified aluminum welding installations and (am allowed by NYS to) inspect aluminum welds

OK, so all can be reasonably skeptical of both - and we can deal with facts, jury style.

-------as to cleaning:

Aluminum is soft - shore a 125, roughly like nylon. Soft material holds hard bits mechanically impinged in the soft matrix.

Aluminum oxide is hard - Rockwell c 50+ like a hardened steel file.

Aluminum oxide lies on the aluminum and unless deepened by anodizing, is only a mil or two thick. (Yes, anodizing is an electrical process that uses charge to increase oxide depth - and current is charge per unit time, and yes, aluminum is sensitive to current density - but don't get ahead. If you guessed that some anti-oxidants consume oxide in electric fields and heat, as in the active anti-oxidant, rather than lay there coating like paint, as in passive anti-oxidant, you already are way ahead. )

Emery is corundum - aluminum oxide containing magnetic "contaminants". Magnetic from iron as in marensite, ferrite, and austenite iron. (welders will see two problems here -but patience - long term degradation from the iron ingrainment comes later)

So when one uses aluminum oxide to clean off aluminum oxide: The result of pushing brittle oxide chips into brittle oxide layers is aluminum oxide shards all over the place. Aluminum oxide ends up being pushed into the soft aluminum, resulting in an aluminum-aluminum oxide matrix on the surface. A conductor filled with resistor bits has less available conductor in the gross area than if the area was all conductor.

Short term - cleaning with emery without increasing contact area to compensate for currenty density changes will result in loss of connection.

But since those who knew changed the aluminum contact sizes and derated the wire capacity, he lucked out and hasn't killed anyone right away. Not because of the cleaning protocol, though- because the other changes assumed some dumbass will not clean properly. And statistically if all clean and a few screw up, remote cahnce of fires. If no one cleans, fires more common

------As to how the wire nut connection functions:

When I - that is I - tested the first wire nuts for miltiary use, the ONLY way they passed the test was for the copper wires to be laid side by side and the nut threaded over the parallel wires. The twisting of the wires before turning on the wire nut did not allow the pressure weld to form. On all sizes tested. Thus, the new-fangled wire nuts were approved for use in rf/power/military ONLY when wires were laid parallel, and NOT when twisted. The nuts may have changed (not that I can see), and the need for the weld may not be required these days- however, I use the metal screw type rather than the spring type. (Hey Paul, Jimmy - you know who this is - I tried to find you guys, but Jimmy said they moved you into a bunker in Quantico - e-mail me) His requirement for twisting the wires before attaching the nuts does not agree with testing. Unless he solders them twisted wires as we used to do many years ago, before wire nuts.

------As to those certified welders chomping at the bit about emery, corundum having iron, and aluminum joints - to have a reliable aluminum weld that lasts over a couple years, any and all iron has to be excluded from the joint. Thus, steel brushes on an aluminum welding table means instant decertification of the installation, steel wool or steel brushes are not even allowed in the area - the harder steel bits break off in the soft aluminum and gets welded into the matrix - and you get embrittlement in a couple years - if it passes the first test. ( only stainless is allowed, and that brush may never leave the weld area in case some rookie will use it on steel - that is all the steel contamination it takes) . Having iron in an aluminum joint embrittles it - be it corundum, steel slivers, or a barbell.

In any connector which assumes a weld, either from pressure or first current from the wirenut preload, iron must be excluded or it will embrittle. And since all aluminum connectors weld at the peak-to-peak contacts of the irregular surface, iron must be excluded.

silicon carbide - yes. pure aluminum oxide - maybe. carundum aka emery - no/

-----As to the original suggestion, from the paper:

Reducing the Fire Hazard in Aluminum-Wired Homes Sept. 12, 2000 p. 4

1. REDUCING THE POSSIBILITY OF CONNECTION OVERHEATING

A. USE OF ANTI-OXIDANT AND ABRASION

To make the lowest resistance and most permanent connections to aluminum wire, the following procedure must be followed:

1) After stripping the insulation off the wire for the proper distance, using a stripping tool that does not nick the wire, coat the bare aluminum with Burndy "Penetrox A" compound. (Caution: some other "oxide inhibitor" compounds sold for the purpose are flammable. Penetrox A is not. Do not substitute.)

2) Abrade the surface of the aluminum wire, with the compound on it, with #240 grit "wet-or-dry" abrasive paper. Maintain the coating of compound while abrading.

[not a problem if silicon carbide is used, but not iron-contaminated corundum, aka emery]

3) Coat mating parts of the connector or terminal with the inhibitor compound.

4) After completing the connection, thoroughly clean off excess compound which is not inside the connection.

------as to the conenction of aluminum wires under a wire nut:

3) Apply "Penetrox A" compound to the aluminum wire(s) and abrade as per Section 1.A.2 above. 4) Hold the stripped ends of the wires parallel, and then twist them tightly together in the clockwise direction using a pair of pliers. 5) Cut off the excess length of bare pretwisted wires.

6) Fill the spring inside the connector with Penetrox A.

7) Screw the Scotchlock connector onto the pretwisted wires as far as it will go.

this is acceptable only if the anti-oxidant is an active one, and if the connector is sized to melt the aluminum laying in contact and to form a weld using first current under spring pressure

otherwise all you have is a wet twisted pair of wires pushed together by a spring -

BTW, I am almost certain he found some anti-oxidants he tried, passive ones, did not survive the current test. Thus he added the sanding step. I would bet that others, active ones, passed with flying colors without sanding. It is not the first time NYS has taken a good idea and went a little too far.

So, you heard facts .. check em if you still wonder.

it is up to you all to determine if axle grease and emery cloth and a pliers is adequate, or if a proper cleaning, proper wire nut, and a proper anti-oxidant is better. On your house.

nuff said.....

On Mon, 03 Nov 2003 12:41:22 GMT, "Nukie Poo" Gave us:

You're full of shit. I'll say it again:

Freshly cut aluminum is not in immediate danger of instant oxidation. For you to think it is, shows you to be of questionable education in that area. Deal with it. I don't need references, you do.

notwithstanding."

Again, translated that means: "I have no references and I'm getting really pissed that you don't accept everything I say as gospel." Sorry Mr. light bulb, your word ain't enough. BTW, when you wrote research papers in school, I bet your bibliography looked something like this:

1. DarkMatter (or whaterver your stupid name is)
2. ibid
3. ibid
4. ibid
5. ibid
6. ibid
7. ibid
8. ibid
9. ibid
10. ibid
11. ibid
12. ibid
13. ibid
14. ibid
15. ibid

On Tue, 04 Nov 2003 03:26:04 GMT, "Nukie Poo" Gave us:

You're a goddamned retarded usenet troll, boy.

The funny part about this whole thing is that I just ran this question by an electrical inspector. He said it was good practice to put antioxidant on big aluminum wires, but they really don't need it and I shouldn't bother trying to fix them.

Well, as with a lot of things, I find that RTFM works best. If the panel manufacturer recommends it, use it. If they say no anti-oxidant required, don't worry too much.

AFAIK, anti-oxidant isn't needed for branch circuit wiring with Al, but that is branch wiring, so there you go.

daestrom

It might be worth mentioning that it is the small branch-circuit type of wiring that has earned Aluminum its' infamous reputation as a fire hazard, not the heavier-gauge feeders and services. The latter is still allowed by the NEC whereas the former is no longer in new installations.

"Nukie Poo @verizon.net>"

Could you cite a specific article, or other information disallowing small gauge Al wiring? What is the specific cut off size?

I'm not a fan of Al wire so this one must have slipped by me.

Thank you.

Louis--

********************************************* Remove the two fish in address to respond

Louis,

I can't cite a reference because I just discovered that I am wrong, according to the 2002 NEC, Articles:

310.2 "(B) Conductor Material. Conductors in this article shall be of aluminum, copper-clad aluminum, or copper unless otherwise specified."

334.104 "Conductors.The insulated power conductors shall be sizes 14 AWG through 2 AWG with copper conductors or sizes 12 AWG through 2 AWG with aluminum or copper-clad aluminum conductors. The signaling conductors shall comply with

780.5."

The practice has been banned in our area for many years; I made an incorrect assumption that the NEC had discontinued its' approval of solid Aluminum conductors for branch circuit wiring. Thanks for making me look it up.

"Nukie Poo @verizon.net>" Louis,

If it makes you feel any better, you were correct in mobile homes, where

550.15 prohibits aluminum for branch circuits. Also, many local codes could prohibit it.

Ben Miller

"Nukie Poo @verizon.net>"

Rats! Sounded like a good idea though!

Thank you.

Louis--

********************************************* Remove the two fish in address to respond

The problem was by the time they identified the problems with aluminum and got them in the (75) code the damage was done. With the new alloy and the CO/ALr devices it is really supposed to work OK. I think another thing is the 3d world is a little more stable and copper is cheaper than it was in the early 70s. When you can get a box of 12/2 copper for $15-20, why would you pay $3-4 for aluminum rated devices? In 1975 I was paying $35 for 12/2 Romex. That would be ~ $70 in today's dollar.

"Nukie Poo

Yeah - but banned or not, can you buy Al #10 or #12 anywhere these days?

Also, on a side note - have you heard that New York State licensing now requires 11 years experience? What's up with that, if it's true?

Too many hacks out there. But I think the test and practical are too easy, at least in my area. I had this one newly-licensed contractor ask me in the supply house the other day what size conduit a 400amp service would require.

It's effectively banned by 110.3(B) and 406.2(C). Listed devices are expensive, hard to find, and GFIs and dimmers are non-existent. Connectors are also a problem. There is a wire nut listed for copper to aluminum connections, but none are listed for aluminum to aluminum. "Nukie Poo @verizon.net>"

Good! Reading this thread got me thinking about my oven. I replaced the thing a couple of years ago, and of course it's wired with aluminum. I had to move the cable, so had to yank the end off to snake the cable through a new hole in the floor. There was no antioxidant, but no obvious sign of any heat or corrosion either, so I just bolted it all back together. I did check to make sure the receptacle was rated CU-AL. I hope al is kosher?