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	Subject - untreated aluminum connections wireman I have seen a lot of aluminum wiring (terminal connections mostly) on jobs that hasn't been treated with anything. My question is; how long does it take for enough corosion to build up before it breaks down the connection. And I've seen some really old stuff that looks perfectly fine. Also, when splicing aluminum should you coat the wire before twisting it together? Or twist, and then coat before screwing on the wire nuts? JimmyDee Aluminum oxide is an insulator. It happens within a year from what I've seen. All aluminum should be coated with the anti-oxidant grease to help keep the termination from oxidizing. Wire should be coated first but I have also filled the wire nut to put more on the splice. I have seen aluminum terminations 20-25 years old that were good and 1 year old that were bad. (no grease or too little) Jim wireman Thanks Jimmy Dee. It makes sense. rick5280 Better check with the manufacturer of the equipment you are terminating. Some forbid the compound (Sq D). From UL, if the manufacturer wants the compound in their terminals, they are required to put it there for you. In other words, you can throw away your squeeze bottle of the black stuff! Rick Miell Ryan_J The NEC doesn't require the use of compound. If it is used, it must be used in accordance with the listing, which typically involves the use of a wire brush. See 110.14 and 110.3(B). Electricmanscott Ryan, the stuff I use says not to wire brush. Scott Vickrey I asked Ideal to repond to this post and they emailed me instead. So here's their response. IDEAL NoAlox antioxidant is a UL-listed material to be used when joining dissimilar metals wherein electrogalvanic corrosion may occur. The most prevalent application is joining aluminum lugs to copper (or copper alloy, such as brass) substrates. Antioxidants are appropriate whenever aluminum materials must be joined to copper or steel. While not specifically listed for this application, IDEAL NoAlox is often used when terminating electrical terminations to DC power sources (such as car, truck, generator, or boat batteries) to prevent the formation of stannous oxide. Moreover, IDEAL NoAlox is often used as an anti-corrosive on the threads of brass light bulb bases prior to installation into aluminum sockets, especially when the environment is humid and corrosion is a problem. Jim MacMurdo Director, Corporate Quality Assurance Ideal's website wireman Bravo Scott So NoAlox should be used when joining dissimilar metals.O.K. Is it not really needed for aluminium to aluminium splices or terminations then? David Hyatt Will it actually hurt to use on aluminum to aluminum splices? I usually try to use on all meters and panel lugs for feeders. I don't use SQ D anyway so thats not a problem. JimmyDee I always used it when splicing aluminum and so did everyone else I knew. To my knowledge, never had a failure. I have had many service calls on some of others failures and you could tell, they had not used the anti-oxidant. I've been told that the oxide of aluminum is a good insulator so it makes sense to use it even if it is not necessarily said to be needed. Jim wireman I believe JimmyDee. Time tested experience usually outweighs theory. earlydean Aluminum will oxide when moisture is present. Use the NoLox or Penetrox when the connections are made outdoors, or in area with high moisture content (damp basements). It is not required in dry areas, but it has never hurt any connection. I use Penetrox on all my aluminum terminations, just to be sure.