I'm trying to understand the real risk of using aluminum today, and conflicting and confusing information doesn't help. I have lots of questions and am not sure where to start.I have gathered the old aluminum that caused all the problems was AA-, and the "new" stuff created in the 70s is the AA- series. Also, I couldn't find the thread, but someone (iwire maybe) once made a comment that larger sizes of wire never had a problem. If so, what is considered the larger sizes. Did 8AWG connections for 30A dryers with the old aluminum have problems?For the larger sizes, say 2AWG and larger for services, do people use antioxidant for all aluminum or just the old . I find it odd the UL says it is based on the recommendation of the connector. Also, I think they say copper and aluminum are the same, which makes even less sense since aluminum oxide is a poor conductor compared with copper oxide. Someone said the series doesn't oxidize (one site I found says otherwise), which if true would also say applying antioxidant should be based on the wire and not the connector.I hear that the series is just as good as copper, which again I don't believe with aluminum oxide being a poor conductor. If the statement is really series installed with antioxidant is as good as copper, I might accept that. But I also hear copper is more forgiving for a bad installation. That to me says copper is better. If an installation could be measured, a higher level is needed for aluminum to be acceptable. What is needed to make the installation of aluminum as good as typical copper installation (for a service lateral)?I torque all my connections in a panel now, even the 14AWG. I always wonder how accurate does the torque need to be. One way that copper could be more forgiving is the torque spec is wider (I don't know what it is). If a lug says 50 in-lb, what is the real range of being a good permanent connection, both for copper and aluminum? Part of my concern is how accurate is the torque wrench being used. Just specifying 50 in-lb as a spec doesn't cut it, unless it is a minimum (which I don't think it is), since it is impossible to torque it to EXACTLY 50 in-lb.Another thing, even if we can say the series aluminum is great and fixes the past problems, I find my suppliers only carry a few sizes that are series. I was surprised to find is not only readily available, it is the only thing available for some sizes. Related to this is the code doesn't say USE, RHH, and others have to the series. Does anyone know why it only requires it for certain insulations (and small conductors nobody makes)?
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I agree with &#;. Often the cheapest, simplest way to answer such a question, is to pay someone who has the means to answer it!However, I will also recommend some simple chemical tests, for the sake of DIY folks. NOTE: While "simple" these methods are NOT SAFE unless proper precautions are taken. I will be discussing the use of some highly corrosive and some mildly toxic substances. Eye protection and gloves are a must! The reactions will also release heat and flammable gasses (also possibly splashing the corrosive contents, so use vessels > 5x bigger than the solutions they contain).By dissolving known quantities of the metal in question in either acid or base you can learn a fair amount about what's in it (I would recommend a gram or two of metal to begin with--larger quantities will give more precision in determining the composition, but danger scales non-linearly with size--if you double the size of your reaction, it is wise to treat it as 4x as dangerous etc.)Aluminum will react with concentrated solutions of sodium hydroxide in water (20 grams of NaOH dissolved in 80 mL water), as will zinc, and probably silicon. Magnesium, nickel, copper and iron will not react with this alkaline solution, and will remain as solid precipitates (note, these precipitates may be quite flammable, even pyrophoric, when dry KEEP THEM WET--see Raney nickel: https://en.wikipedia.org/wiki/Raney_nickel Aluminum, zinc, magnesium and iron will all react with concentrated solutions of hydrochloric acid (add 30 mL of concentrated HCl, sometimes called muriatic acid, to 70 mL water). This will leave nickel, copper, and silicon behind.In each case you can separate out the precipitates (by filtration or centrifugation, or just decanting.) KEEP THEM WET! They can then be dissolved using nitric acid. The species in solutions (original and dissolved precipitates) can be determined by reaction with chemical indicators (such as 2,10-phenanthroline) or by using solubility profiles to selectively precipitate out salts of each metal.AGAIN: DON'T TRY any of this until you have done your research, figure out how to protect yourself (and your friends, family, pets, neighbors etc.) and have a plan for executing the experiments, as well as contingency plans for spills and fires (be prepared!)
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