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Multi-strand AL


charlieb
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I've used a comment for years. Today I had "feedback" from a builder asking for a source for my comment.

" Multi-strand aluminum wire should have an anti-oxidation compound to prevent oxidation. Oxidation can cause a poor connection."

His request came at a good time. I have been working on a rewrite of my comments that has all comments defendable. No subjective comments.

So, is there a source for such a comment or did I create it in my sleep one night?

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Doug Hansen't comment on this issue taken from Electrical Inspection of Existing Dwellings - 2001 Edition:

"While not strictly required by code, the presence of anti-oxidant at all terminals would be an indication of a higher level of quality in workmanship."id="maroon">

ONE TEAM - ONE FIGHT!!!

Mike

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The NEC doesn't require it unless either the wire manufacturer or the panel manufacturer requires it.

I've seen GE and Murray panels that have specified using an anti oxidant compound when connecting aluminum wires to the panel lugs. They were both older panels. I've never seen instructions with wire.

In my area, it isn't much of an issue. The local munis require it, so the local electricians do it. It's not like some big burden, after all.

In the rare case where I don't see it, I look at the panel instructions. If they don't mention it, I don't either.

- Jim Katen, Oregon

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I emailed Douglas,

What I guy.

His response, for everyone's edification

There is a standard published by NECA (National Electrical Contractors Association) and the aluminum association. It’s called NECA/AA 104-2000 – Installing Aluminum Building Wire and Cable. It specifically recommends anti-oxidant for all aluminum cables #6 and larger. The material in that book mirrors the installation guidelines from Alcan, at www.cable.alcan.com. Southwire also publishes guidelines for their wire, and it does not include the specific recommendation about anti-oxidant (at least not in the 2005 copy in my file).

I think the main reason for using it is lubrication. Large lugs typically come with anti-oxidant packed inside them. It’s not that the manufacturer is assuming you will be inserting aluminum – it’s that whatever you are using is going to require a specific amount of torque, set by a torque wrench, and that the precise amount of torque is easier to obtain if there is something to lubricate the connection.

You’ve probably experienced this yourself, or if not, can imagine it. You’re tightening a large aluminum conductor. As you tighten it, you hear a sound like fingernails on a blackboard as it scrapes and crushes the aluminum into the shape of the lug. Surely that’s not a good thing. It’s also important that the lug be tightened to the exact specifications written on it or the panel – not too tight and not too loose. Around here, the city inspectors carry torque screwdrivers and torque wrenches. They will loan them exactly once to each new electrician. After that, if they show up to a job, and the electrician doesn’t have his own torque tools on site, it is an automatic correction notice. Good connections depend on proper pressure. Anti-oxidant helps you get that pressure.

As an added bonus, it will help prevent oxidation from building up at the exposed connection. In a lot of environments, that isn’t an issue. If you are in a hot or humid climate or near a body of salt water, it makes a lot of difference.

For what it’s worth, I don’t agree with Dr. Aronstein’s new piece at Dan Friedman’s web site. He lost me with his stuff about sanding down each exposed aluminum wire with emery cloth soaked in anti-oxidant. The amount of oxidation that forms on the surface of a piece of aluminum when the insulation is stripped and it is first exposed to air is negligible – it is measured in angstroms for goodness sake – and it is easily broken through by the pressure of the terminal. That is one more reason to exactly follow the torque specifications for the lug.

So yes, anti-oxidant is not strictly required by code, but…

If this causes you to lose the argument with the builder, ask to see his torque screwdriver…

Feel free to share this with the TIJ gang if you like.

Douglas Hansen

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Originally posted by Jim Katen

The NEC doesn't require it unless either the wire manufacturer or the panel manufacturer requires it.

I've seen GE and Murray panels that have specified using an anti oxidant compound when connecting aluminum wires to the panel lugs. They were both older panels. I've never seen instructions with wire.

In my area, it isn't much of an issue. The local munis require it, so the local electricians do it. It's not like some big burden, after all.

In the rare case where I don't see it, I look at the panel instructions. If they don't mention it, I don't either.

- Jim Katen, Oregon

In my market it is seldom applied. I've never seen it applied pre the mfr instructions. Among the common defect list are doubled neutrals, intermixing of neutrals and grounds, non-listed products inside the enclosure, no means of securing the NM cable and non listed breakers. This is new construction! I find the bus bars painted about 5% of the time.

As Mike O would say OTOF

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