[TowerTalk] Fwd: UV and WX deterioration of THHN insulation, and effects

[Hans Hammarquist]

 I think Partick has a point. Why is the current trying to go through the insulating top layer of the copper wire.

Now, if you study the skin effect and apply the formulas you will find out that the skin effect on an insulating layer is very, very deep to the point that hardly any (actually non to pay attention to) is going via the insulator. Same thing with the oxidized layer on a bare copper wire. The skin effect "sends" all (almost) to the conducting copper wire. The only time there might be a problem is if the corroded layer is conducting enough to carry a sizable amount of current and thereby cause attenuation. I doubt that the THHN isolation can deteriorate to a conducting phase. 

Aluminum wires have the advantage that aluminum oxide is not conducting unlike copper oxide, the red oxide, is. 

Man, this start to be complicated. Better find that North Seeking Owl.

Hans - N2JFS

 

 

-----Ursprüngliche Mitteilung----- 
Von: Patrick Greenlee <patrick_g at windstream.net>
An: towertalk <towertalk at contesting.com>
Verschickt: Mi, 28 Dez 2016 8:57 am
Betreff: Re: [TowerTalk] UV and WX deterioration of THHN insulation, and effects

Skin effect... If skin effect can force conduction into the outer limit 
of the wire (the chemically altered part with poor conductivity) then 
why doesn't the skin effect force conduction out into the insulation and 
really have poor conduction? (or in bare wire out into the surrounding air)