First Brucedp5 said: >> So is aluminum that such a good idea for power line/wiring use of any kind? Then David Roden responded:
Aluminum wire has been used for larger (stranded) power cables for many decades, and it's given good service. You do have to size it larger because of its higher resistance, and use Noalox or other goop on the connections to prevent oxidation from raising the resistance at the connection. For a while, IIRC something over 4 decades ago, solid AL building wire in #12 and #14 was used in place of #14 and #14 for residential branch circuits. It proved to be unreliable and hazardous. I think that was because the solid (vs stranded) wire deformed too much under receptacle and switch terminal screws. With thermal cycling the connections loosened, developed oxidation, and heated up. There were some home fires as a result. But AL is fine in larger sizes and in stranded type. Like a lot of things, aluminum wire is just fine when used properly. David is correct about the issue with aluminum wiring in houses several decades ago. Except for very old stuff, almost all overhead power lines that your utility uses is a composite wire consisting of a steel core with an aluminum jacket. It is called aluminum cable steel reinforced (or ACSR) - and yes, I've seen a few other names for it. Pure aluminum does not have the tensile strength for long spans without breaking. Because of skin effect, the outer portion of a wire is carrying most of the current, so having a steel core does not affect the current carrying capability much. The stuff I have seen has individual wires a little under quarter inch in diameter with the steel core being about 1/3 of the diameter. Cables are made from a bunch of these wires. What I was holding was a bundle about an inch and a half in diameter. If more current capacity was needed on high voltage transmission lines, multiple cables were run together - generally spaced about 6 inches or so apart (maintained by spacers) and hung from the same insulator strings. Two or three cables is common. This is generally called "bundled cables". This is not to be confused by the three separate phases that are on separate insulators. ACSR is also made with several steel wires in the center of the cable with pule aluminum wires surrounding it. Jim Walls -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.evdl.org/private.cgi/ev-evdl.org/attachments/20160414/ea339ba9/attachment.htm> _______________________________________________ UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub http://lists.evdl.org/listinfo.cgi/ev-evdl.org Read EVAngel's EV News at http://evdl.org/evln/ Please discuss EV drag racing at NEDRA (http://groups.yahoo.com/group/NEDRA)
