ECN Forum Forums General Topics of the Trade General Discussion Area Question on using aluminum

Ryan says, and I agree..

"I don't think I have ever seen anti-oxidant compound used in accordance with the manufacturer's instructions, which typically require the use of a wire brush."

But, I always put the anti-oxidant on a tooth brush sized wire brush (scratch brush) and work it into the conductors. It breaks the oxidation layer and works the compound into the individual strands.
Whether or not it helps I don't know (I believe it does), but I've seen several failures at meter sockets where a small dab of no-alox was just squeezed onto the conductor without spreading it.
It takes less than 30 seconds for each wire and seems to result in a "better job".

Bob,
Aluminum oxide is an insulator and forms almost instinctually when bare aluminum is exposed to air. The use of an anti-oxidant prevents the oxide from forming if correctly done. In many cases this required the use of a wire brush to remove the aluminum oxide after the anti-oxidant is applied to the wire. The other thing that helps is that the aluminum oxide is very brittle and the normal installation practices should shatter the oxide providing a bare connection, but if the termination is not "gas tight" the oxide will soon reform and may result in a failed connection. This brittleness is the basis for the use of pre-filled connectors. The crimping action will break the oxide and the anti-oxidant will prevent it from reforming. If you are sure that your connection will remain 100% gas tight, then there is no need for the anti-oxidant.
Don

quote"Live near an ocean and one would sing a different tune about no-ox.... Without it AL turns into a block of chalk over time."

Yep, I agree whole heartedly. The windward sides of the Island I live on get salt air that is like fog some days. It does havoc on terminations that have no antioxidant, or at least no recent applications of anti oxidant. Aluminimum screen frames are equally subjected to the yellow grundge oxidation factor.

Don, the same could also be said for copper to a FAR LESSER degree. Lesser to the point that only extreme cases are even recognized. Green/white patina copper oxidization is equally bad.

Even though not "required" on AL, failure to do so here will raise some eye-brows with Inspectors here. Call it workmanship.... If it is "snake-oil", it keeps Inspectors out of my hair....

e57,
Copper oxide is conductive, aluminum oxide is an insulator.
Don

Note bold "Far Lesser", and "to the point that only extreme cases are even recognized." Think about it the next time you need to make a scratch to test for voltage. Apparently copper oxide films were one of the first noted semi-conductors..... Anyway, point was oxidation = bad.

We're starting to use Al more and more on services and sub-panels, with the increasing price of copper. We always use Penetrox, yet the Poco here NEVER uses any Penetrox on their aluminum conductors...even the ones they terminate in meters for underground services.

For larger feeders and services, we always use al unless spec for cpr. Not a problem if installed correctly. As for noalox, always use it on the conductor and the termination threads.