Summary for pvc insulation contamination Discussion
Contamination from additives in wire insulation is the likely issue behind the observed contact resistance differences, not the bulk copper conductivity. Tobias D. reports that some fine-stranded wires gave poor voltage-drop results in spring clamp terminations even when the copper looked clean, while other wires with visibly oxidized strands performed better. He also found that cleaning the strands with ethanol improved the measurements, suggesting a surface film or residue on the copper. He notes that the copper conductance from different manufacturers was similar, so the problem appears to be on the strand surface, possibly from insulation additives migrating out of PVC or even halogen-free jackets. The thread does not give a definitive chemical explanation, but it points toward contamination from the insulation material affecting the contact interface. Manish Tripathi adds a related question about why PVC insulation causes copper tarnish.
Q. I work on the optimization of the voltage drop of electrical connectors with a wire termination. Especially for fine stranded wires I observed an influence of the “wire quality” on the voltage drop. Some wires had really poor measured values, but the copper was not coloured. Other conductors with black, oxidized copper strands had better values that the not coloured strands. Cleaning the wires with bad voltage drops in ethanol improved the values.
At least in Germany, fine stranded wires are defined by the electrical conductivity, not by the actual diameter. I determined the conductance of the copper material of some wire manufacturer, there are no notable differences. But if I connect the wires to a spring clamp connection and measure the voltage drop between the tin coated copper bar and the wire there are large differences. The reason has to be found on the surface of the strands and I am sure it is not (only) oxidation. Some halogen free wires had also high voltage drops. So I suppose that the contamination results from any additives of the insulation material. After cleaning with ethanol the voltage drop becomes much better. I am interested in information about the additives, its migration and the effects on the copper surface.
Tobias D.
– NRW, Germany
October 11, 2016
Q. Why after PVC insulation Copper Tarnishes?
MANISH TRIPATHI
TAMRA DHATU – BHIWADI,ALWAR.RAJASTHAN
October 16, 2016