John T {green wiring}

A question for you that has been buggin' me. Does the "green powder oxidization" inside a bat cable casing have any affect on the current carrying function of the cable. We're talking powder the full length of the cable BUT no breaks and good clean connections at both ends? I guess I'm asking whether current travels in the individual wires or does it travel over the surface and what role does the powder play if any? Thanks in advance for your reply. RB

EXCELLENT QUESTION, Im no metallurgist or chemist but here are my thoughts:

Does the "green powder oxidization" inside a bat cable casing have any affect on the current carrying function of the cable. That whats called "patina" spelling????????? Green copper oxide???


Looks to me like the chemical process of oxidation causes the breakdown of some of the copper (you now have less wire circular mils) and converts it to some extent to a conductor (copper oxide) thats likely higher resistance then the pure copper it was before, SO MY BEST GUESS IS THE NET RESULT IS SLIGHTLY MORE RESISTANCE (now less copper in paralell with higher resistance copper oxide) THEN IF IT WAS STILL PURE COPPER

I guess I'm asking whether current travels in the individual wires or does it travel over the surface and what role does the powder play if any?

Sure current travels in the wires and at that low DC frequency "skin effect" is negligible but again it looks like you now have less pure copper as part of it got converted to copper oxide so you have copper in paralell with higher resistance copper oxide SO ID GUESS WIRE THATS PART OXIDIZED has to be more resistive then if it were still pure copper

Hey, this is as much a chemistry and metallurgy question then electrical engineering and IM NOT knowledgeable on EITHER so no warranty but still the above makes sense to me. Less copper and instead some of it now copper oxide just has to be a worse conductor then if all still in the pure copper state??????

John T

I'm not John, just an imposter lol. Electricity with higher frequencies (in the U.S. it is 60 HZ or 60 cycles per second) it tends to travel on the surface, what they call the skin effect. If we were to increase the frequency to 400 hz, then the skin effect would be much greater. With DC voltage there is not a frequency to help this skin effect so I believe that it is through the entire wire. My guess is the oxidation would hinder the current flow some, but I have no idea how much. good question so I will wait for an answer with you

oops John beat me to it.

Any time you have green crud in a bettery cable it is time to replace the cable!!!!!!!!!! I have seen semi trucks not start because or green crud on/in one cable and I replace that cable!!!!!!! End of problem! Armand

Any time you have green crud in a battery cable it is time to replace the cable!!!!!!!!!! I have seen semi trucks not start because of green crud on/in one cable and I replace that cable!!!!!!! End of problem! Armand

From Argonne National Laboratory's Educational Programs---"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 [commonly found] temperature.

Copper oxide was used in rectifiers in the early days of the 1900s (before Selenium or Gallium Arsenide, or silicon diodes) Jim

Thanks Jim, I kinda figured copper or other metallic oxides arent great conductors. That green lookin copper oxide??? powdery substance cant be as good as the copper from whence it came for conducting electricity where free readily available electrons are needed in the outer shell......

Hey this ought to be right down your alley right Professor??????

John T

Green Patina: much admired natural protective coating of a blue-green patina characterizes older copper roofs, including ancient cathedrals as well as bronze statues and other copper metal surfaces exposed to the weather. Because of the time required to achieve this, much research has been done on artificial patination, with varying success.

In natural patination the major coloring agent in the film is basic copper sulfate.

Have a feeling battery acid, H2SO4, is turning copper into a copper sulfate.

My current alley is paved with asphalt, but I was into 208 3 phase today making room in my laboratory for a new CNC lathe - 15" swing HAAS. I have a very old TIG/Stick welder that has at least 100 pounds of Selenium rectifier in it. 200 amps of rectification at 40 volts (open circuit). The High freq. system is oscillator driven. (I think there are Flemming Valves hiding in there!!!) Jim

I was told that the electrons travel over the outside of a strand of wire. This was explained to me how stranded wire conducts electricity better than solid copper. If this is true then I think oxidation would degrade the conductivity of the wire.

(quoted from post at 18:36:34 06/05/13) A question for you that has been buggin' me. Does the "green powder oxidization" inside a bat cable casing have any affect on the current carrying function of the cable. We're talking powder the full length of the cable BUT no breaks and good clean connections at both ends? I guess I'm asking whether current travels in the individual wires or does it travel over the surface and what role does the powder play if any? Thanks in advance for your reply. RB

Click to expand...

electrons repell each other and end up equally spaced away from each other. this is why they tend to flow more on the outer than inner. some say frequency enhances, others say current flow, then some say pressure or voltage will enhance it by putting more electrons into the same space. If the power is only external, it will have very little effect, only to the effect of the loss of some of the conductor, which should be a factor of less than 10 million to one. If the copper in breaking down internally then the factor of loss could be 100 to 1 or even 10 to one and become significant. Connections on both ends and conductor

From my old radar fixin' days (Raytheon and Lear-Siegler units): at extremely high frequencies, the skin effect becomes so great that the waveguide that carries the energy is hollow, much like a rectangular pipe. IIRC the cross section of the tube is calculated using the wave length of the carrier on whichever axis is used to polarize the antenna. Typically the waveguide inner surface is gold plated, and the pipe is pressurized to prevent moisture intrusion which due to localized heating of condensate will cause severe degradation of the system. Also seem to recall that the THEORETICALLY calculated speed of the propagated energy in the waveguide can be somewhat greater than the speed of light in some systems. Been a long time, this is subject to constructive revision based on technological advances and corrections to an aged memory!
Checking edit function!

Thanks very much to all who posted. Some were over my head but I got what I was asking for and more. Thanks again. RB

I have had an old 84 F250 4x4 that runs a 460 engine for a long time. For a while, it had the odd problem of starting fine cold, but hardly turning over when it had been stopped for a few minutes after coming up to normal operating temperature. This puzzled me, because the battery cables looked great on the outside, the battery was new, the connections were shiny and it didn"t happen EVERY time. I messed around with the truck being somewhat unreliable for a couple of years, trying this and that.

Finally I tried changing the battery cables, and the problem went away. I decided to investigate and cut into the insulation on the old positive cable. Inside the outwardly perfect looking insulation, I found mostly blue powder. There were less than 10 strands of copper wire that had not oxidized and come apart. I was surprised that the old truck would start at all with that cable!

So, to answer your question, yes, the corrosion does reduce the amount of current a cable can carry. Just how and why a cable can corrode inside without any outward sign remains a puzzle. But that was what happened with my truck. And now I examine battery cables much more closely when one of my machines has a starting problem.

I would replace the cable with a quality new one. Good luck!

When a cable starts looking green a little oil will stop the process.Braided cable is for flexibility.Try some 0 gauge solid wire on your welder leads.If you believe in the skin effect on DC some copper pipe would make a better conductor.