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Tricks Of The Trade: Mythbusting the Copper vs. Aluminum Debate

Written by Retired Columnist. Posted in Ask The Expert, Columnists, Magazine, Retired Columnists, Topics, Tricks of the Trade

Published on January 30, 2008 with No Comments

By James C. Elledge, IFMA Fellow, CFM, FMA, RPA, RIAQM
Published in the January 2008 issue of Today’s Facility Manager

QI have a question about aluminum vs. copper electricalwiring—particularly when connected to large, main electrical switchgears. I have been told that “in the old days,” large aluminum mainfeeders (connected to switch gears) would expand and contract overtime, and their lug connections would become loose. This would create ahuge problem (and fire risk) for any building. According to anelectrical contractor involved in one our projects, the new aluminumconductors are designed much better and don’t have this problem anymore.

Mycompany’s standard practice for 20 years has been to use copperconductors, but with the price of copper going through the roof, we’dsave a huge amount of money by using aluminum.

My chiefengineer had some problems with aluminum in an older building and wantsto stick with copper. But since code allows either, I wanted toinvestigate all of my options. What’s your opinion?

Name withheld upon request

AHere are a few excerpts from a 1995 white paper from Copper.org that make the case for copper:

“Copperis recognized as the quality product, while aluminum is mainly usedbecause it is cheaper. It [aluminum] has been successful mainly inoffice buildings and shopping centers where cost pressures aregreatest, and where quality materials are sometimes squeezed out in thebidding process.

“Copper’s unquestioned superiority overaluminum building wire is at the point of connection. Although improvedaluminum building wire materials have been developed to alleviate thetendency for connections to loosen as the metal ‘cold creeps,’ noamount of alloying will change the inherent nature of aluminum toimmediately form, upon exposure of a fresh surface to air, a tightlyadherent, high resistance oxide film.

“A survey of U.S.electrical contractors on their preference of building wire materialsshowed that they preferred copper 20 to 1 over aluminum. The onlyreasons for using aluminum were for lower first cost and light weight.Copper was considered superior in all other respects.”

Now for the other side of the argument, from Christel Hunter, a senior field applications engineer with Alcan Cable:

“Aluminumwiring was evaluated and listed by Underwriter’s Laboratories forinterior wiring applications in 1946; however, it was not used heavilyuntil 1965. At that time, copper shortages and high prices made theinstallation of aluminum branch circuit conductors an attractivealternative.

“As aluminum wire was installed more frequently,the industry discovered that changes were needed to improve the meansof connecting and terminating smaller aluminum wire. The use of steelscrews with utility grade aluminum wire resulted in a connection pointthat was more sensitive than copper or aluminum wire terminated withthe previously used brass screws. Almost all reported problems involved10 AWG and 12 AWG branch circuit connections.

Several factorsled to the reported failures of aluminum conductors with steel screws.One of the most often cited reports on aluminum wiring, “The Report ofthe Commission of Inquiry on Aluminum Building Wire,” evaluatedinformation published between 1941 and 1978 and identified 19 differentfactors that might have affected the contact resistance of aluminumwiring. The most likely and often identified culprits were:workmanship, thermal expansion differences, and creep.

“However,newer AA-8000 aluminum alloys have creep rates very similar to copperbuilding wire. This means that AA-8000 conductors perform very muchlike copper conductors at terminations.

“Corrosion is oftencited as a contributing cause of failure at aluminum connections.Nowadays, a thin, protective layer of oxide on aluminum conductorscontributes to the excellent corrosion resistance of aluminum. Whenterminations are made correctly, the oxide layer is broken during thetermination process, allowing the necessary contact to be made betweenconducting surfaces.

“Furthermore, AA-8000 series aluminumalloy building wires are manufactured according to ASTM B-800. In theU.S., they are generally compact stranded according to ASTM B-801.Equal ampacity AA-8000 aluminum and copper conductors can usually beinstalled in the same size conduit.”

The early installers ofaluminum tended to use the wrong product to save money. That’s an easyenough problem to solve, but when someone has a bad experience withaluminum, it is very difficult to get that person to use it again.Maybe this is what happened to your chief engineer.

So whathave we learned? I think we’ve busted the myth that aluminum wiring isunsafe and should never be used for commercial purposes. If you use theright product for the job and follow proper installation practices,aluminum wiring may be up to the test. With copper demand so strongworldwide, it might not be such a bad idea to consider aluminum as aviable option for large wiring projects.

Elledge,facility/office services manager for Dallas, TX-based Summit AllianceCompanies, is the recipient of the Distinguished Author Award from theInternational Facility Management Association (IFMA), is an IFMA Fellow, and isa member of TFM’sEditorial Advisory Board. All questions have been submitted via the “Ask TheExpert” portion of the magazine’s Web site. To pose a question, visit this link.

About Retired Columnist

This expert formerly served as regular contributor to Today’s Facility Manager magazine. His vast knowledge of the facility management profession continues to provide a rich resource for facility managers by way of this online archive.

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