Oxidized wire

[lionelsoni]

In the "Questions-Answers" feature of the February, 2014, CTT, there is an item from one Greg Hurd about an American Flyer accessory that includes this:

"Another source of power loss is the wiring.  The earliest postwar log loaders had insulated cotton wire.  Air penetrates the cotton with age and oxidizes the metal surface of the wire.  This adds resistance and thus results in a voltage drop that can cause the motor to fail...."

The current flows almost completely uniformly through the cross-section of the wire, making any loss of copper by oxidation at the surface completely negligible.  The idea that oxidation would reduce the wire conductance to any noticeable extent may come from a common misunderstanding of the skin effect.  This is a phenomenon that does indeed concentrate the current in the outer part of a conductor, but to an extent that depends on the material's conductivity and on the frequency of the current.  At 60 hertz, the skin depth (the approximate thickness of the current-carrying skin) is 5/16 inch, far greater than the dimensions of wire used in any toy-train model.

[ADCX Rob]

I don't know how these things get to print.  There should be more fact checking somewhere.

[Buckeye Riveter]

Bob...After reading your comment, I went looking for the article and I agree whole heartily with your comments, and.............

In the same Q&A, the writer states that he uses rubbing and isopropyl alcohol to remove old grease from a 751 log loader, but then states that it can damage Flyer paint.   Why would I want to use something to clean that could possible ruin the paint?  If I were giving a tip on how to clean, I can't imagine proposing something in a publication that could harm the paint.   The article should propose using something that cleans the grease and does not harm the paint.  

This is a 751 log loader

cEQTnH XKO4