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Name: Glenn C.
Status: Educator
Age: 30s
Location: N/A
Country: N/A
Date: 2001


Question:
I am a safety instructor for 45 electric co-operatives in Minnesota. Recently I was asked by a power line worker, which is a better conductor- Copper or Copper Oxide. While I have been cruising around the web, I seem to find mostly that the copper oxide works best in superconductor applications. The line workers I instruct deal in kilovolts in various aluminum and copper wire conductors on a daily basis as they work at an electric utility. What is a straight forward answer I can use? Is the copper oxide better? Is that only in superconducting applications? Is the copper oxide found in corroded (when exposed to the weather) copper connections related? If so, then why does it act as resistance at typical ambient temperatures?



Replies:
At temperatures your workers will encounter, copper metal is a MUCH better conductor than copper oxide. The new "high temperature" superconductors (which actually are superconducting only at temperatures far below that of dry ice) contain copper and oxygen, but they also must contain other elements, such as yttrium and barium, as well. Copper oxide alone doesn't do the trick.

Richard E. Barrans Jr., Ph.D.
Assistant Director
PG Research Foundation, Darien, Illinois


Metal oxides are generally not very good conductors, in fact, most are dielectrics and hence non-conductors. Some metal oxides are semi-conductors (and also super conductors at low temperature in some cases). Certainly, copper and aluminum are much better conductors than their corresponding oxides at any temperature linemen will encounter.

Copper, lead, and aluminum oxides formed by corrosion are decidedly poor conductors. I am not an electrical engineer but I know if I let the terminals of a battery become corroded, the battery no longer delivers electricity (i.e. the corrosion products are insulators).

Superconductivity -- the disappearance of electrical resistance -- only operates at very low temperatures obtainable only in labs at the present time -- although there is a lot of research seeking higher temperature superconductors.

Most metals, including copper and aluminum, form thin metal oxide film layers when exposed to air for even a brief time -- this is what makes a new penny turn dull after a few days or weeks. These oxide layers are so thin however that for all practical purposes they do not interfere with the conductivity across such layers.

Vince Calder



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