Can copper wire get more resistive with time?

[JL Sargent]

We do some non-destructive electrical testing at work. The subject came up whether copper wire can get more resistive simply from age and or weathering. I suspect it can. What do you think?

[christ1]

The wire can/will corrode over time and will increase the resistance. But the copper wire itself is not changing resistance. It is the corroded oxide layer that forms on the copper surface which has a higher resistance resulting in the overall measured resistance to increase.

With regard to speaker wire, you can cut off a small section and re-strip the wire to reveal uncorroded wire. With all that said, the amount of resistance change in speaker wire applications is generally going to be negligible.

[Don Richard]

External corrosion won't affect DC resistance significantly, but it can impact skin effect to varying degrees

[Guest " "]

External corrosion won't affect DC resistance significantly, but it can impact skin effect to varying degrees

For audio purposes....the above is an important statement.

If we accept the premise that the frequency determines how close to the shin transmission occurs....and understand at what frequency skin effect begins depending on wire guage of the individual strands. SO the answer needs to include an analisys of the wire strand gauge to identify the % skin effect at varying frequencies.....then you need to establish that those frequencies are relevent to audio.....some are...some are not. Emphasis on understanding this at the wire strand guage level not the wire bundle level.

[T.H.E. Droid]

In short, no. The main problem with aging is your terminals at each end and/or a mechanical defect such as breaking strands from overflexing or pinching. Crimped or even soldered terminal ends can easily corrode over time resulting in high resistance or even failure.

[boom3]

The answer is to remove and clean connections from time to time to prevent contact rectification due to oxidation.. Bulk resistivity of metallic conductors does not change merely with age. If subjected to some extreme stresses, they may develop internal fractures, but "extreme" is the key word here.

[sunnysal]

AC current and high frequencies would be most affected by corrosion on a wire´s surface. DC at audio frequencies MUCH less so. however given the extreme eye for detail many audio lovers have it is not impossible to assume that people would want to maintain nice, shiny., corrosion free wires. needless to say corroded connections are a problem. T