I think it is important for me to dispel a few quotes about Aluminum Wiring that I read in posts from time to time and in a NACHI Article. And for the purposes of this post…here is a link to that Article
Quote # 1 - The NACHI Article quoted “inherent weaknesses were discovered in the metal that lead to its disuse as a branch wiring material.”
Fact : That is incorrect, the issue was less about the compound and more about the improper terminations and installation practices of the product and less about the weaknesses in the aluminum itself. The issue during that period did however lead to industry changed in the compounds that helped elevate AA 8000 series to the building wire industry."
Quote # 2 - The NACHI Article quoted “aluminum will generally become defective faster than copper due to certain qualities inherent in the metal.”
Fact : The term “defective” is misleading and boarders on slander really. When Aluminum is properly maintained, terminated properly and is used in accordance with correct installation practices, it’s life span is equal to any other wiring compound. Do not get me wrong, I am a COPPER man but I would never say Aluminum becomes defective faster with all installation practices being equivalent. Poor workmanship and bad installation habits reduce the life expectancy of any system regardless of the conductive material being used.
Quote # 3 - The NACHI Article quoted: “In addition, the presence of single-strand aluminum wiring may void a home’s insurance policies.”
Fact : The dwelling that has AL wiring for their branch circuits may have trouble getting insurance depending on the misunderstanding of the insurer but how could having AL single stranded AL void a warranty that someone got in the first place…if they got the insurance then the insurer new it had AL wiring in the first place. Now, it may affect if you change insurers or someone buys a house that a new insurer disliked AL branch wiring but not sure how it would void a warranty since it is assumed you had it in the first place and no one is installing new single strand AL wiring anymore…not since the early 70’s.
Quote # 4 - The NACHI Article quoted “On April, 28, 1974, two people were killed in a house fire in Hampton Bays, New York. Fire officials determined that the fire was caused by a faulty aluminum wire connection at an outlet.”
Fact: While this may be true, the article is about the AL Wiring and not the terminations. Any connection will go south if the terminations are not done correctly, how many electricians do you think actually use a Torque Wrench or Torque Screw Driver on their terminations…come on now…be honest with yourself before you answer that question.
Quote # 5 - The NACHI Article quotes “Aluminum possesses certain qualities that, compared with copper, make it an undesirable material as an electrical conductor.”
Fact: - So we know that CU has (1) Electron the VAL Shell and AL has (3) Electrons in the VAL Shell…ok…we know that the DC resistance of the two are not similar…but then again…we know this and adjust for this in a size per amp basis…the larger the conductor the less resistance. Now I will not venture into AC reactance, capacitance and complex impedance since it was not discussed in this article…but there is a reason we upsize AL from CU…but I would not go as far as saying it is “undesirable material”…Just sayin!
Quote # 6 - The NACHI Article quotes less ductile. Aluminum will fatigue and break down more readily when subjected to bending and other forms of abuse than copper, which is more ductile. Fatigue will cause the wire to break down internally and will increasingly resist electrical current, leading to a buildup of excessive heat."
Fact: The old AA1350 was prone to that IF you installed it using a poor workmanship type manner. Granted we can’t watch every installation and determine what was installed improperly…However, the bending done during an installation process is usually not the same type of being tolerances one would experience with a piece of AA 1350, stripped of it’s protective insulation…and just bending it back and forth until heat builds up and the product fails…so considering Apples to Apples…I would worry more about the terminations itself than the actual wiring. Now, in the examples of fires…provide us one example of the actual AL wiring failing…other than the terminations (Connections)…and I will show you both CU and AL termination failures…
Quote# 7- The NACHI Article quotes “galvanic corrosion. In the presence of moisture, aluminum will undergo galvanic corrosion when it comes into contact with certain dissimilar metals.”
Fact: While the galvanic action is true…less us not forget it can happen in any situation where dissimilar metals are in contact. Any conductor that is installed needs to be observed carefully in any environment that it is placed.
Quote # 8 - The NACHI Article quotes oxidation. Exposure to oxygen in the air causes deterioration to the outer surface of the wire. This process is called oxidation. Aluminum wire is more easily oxidized than copper wire, and the compound formed by this process – aluminum oxide – is less conductive than copper oxide. As time passes, oxidation can deteriorate connections and present a fire hazard. "
Fact: it is true that AL is prone to AL Oxide and Oxidation and that specific compound or complex compound it is less conductive then a conductor without it at the terminations. However, on a properly installed termination that is torqued correctly the mechanical bond of the lug or screw to the contact points on the material will lessen the AL Oxidation process. In fact, in many cases the AL Oxide is only an initial corrosion type event and then provides a protective barrier to further corrosion. it does not affect the current carrying capacity of the conductor itself…so when using AL it is critical to terminate properly…Torque properly…use the correct type of lugs for the material being used…and clean the AL prior to termination…if this is done the AL Oxide will not breach the contact points on the material and the termination…again it is all about how you do the termination…having AL Oxidation on an AL Conductor in of itself is not a problem and will not alter the performance of the product.
Quote #8 - The NACHI Article quoted greater malleability. Aluminum is soft and malleable, meaning it is highly sensitive to compression. After a screw has been over-tightened on aluminum wiring, for instance, the wire will continue to deform or “flow” even after the tightening has ceased. This deformation will create a loose connection and increase electrical resistance in that location."
Fact: well the basis of this is correct. I would simply say that over compressing any conductor (AL or CU) will damage the connection which is why it is so important to get to know what a Torque Wrench or Torque Screw Driver is and how to properly use it…What you are referring to in the “loose connection” is referred to as “Creep” in the Wire and Cable Industry. Again it comes down to properly torquing a termination. You see…installer error might be more forgiving on CU than AL…but then again thats why the Electricians get paid the big bucks…(sarcasm)…If you install a 4/0 AL in an SE Cable to a lug and you do not use a torque wrench…then you are not doing your job properly…thats my opinion…learn how to use your equipment or leave the trade…Also in the Article it talks about expansion and contraction…FYI…all metals do this…read above to solve that issue.
OK…I will leave the rest of that Article alone because it does present some information that is very helpful to those individuals who are dealing with Insurance related issues or so on. However, the real problem I have with the article is the blanket statement that sums up the article.
NACHI quoted " In summary, aluminum wiring can be a fire hazard due to inherent qualities of the metal. Inspectors should be capable of identifying this type of wiring."
I STRONGLY DISAGREE…and I am a COPPER GUY at heart…the statement tends to lean in a direction that all AL Wiring is a fire hazard and that the inherent qualities of the metal are a poor conductor. The NFPA has listed AL within the NFPA 70 for many years and is still listed…We use AL for Service Conductors, Feeders in all types of applications without an problems. In fact, 9 of 10 homes inspectors right now probably have an AL Service Entrance Cable, Service Drop, Service Conductors Overhead or Underground and numerous feeders in their home as we speak…if you wish to call out AL Branch Circuit Wiring then so be it…but I would focus less on the compound itself and more on the actual improper terminations…and more on how AL has evolved as a result of the negative results of the late 60’s and early 70’s…
Here is a Summary- The Aluminum used TODAY is not the same Aluminum used in the building trades of YESTERYEAR. It has EVOLVED; giving AL in general a black-eye is misleading at best in my opinion.
Now those are my opinions…to which I am entitled.