BTW - the main purpose of painting, anodizing, plating, and phosphate treatment is to impede corrosion. Painting is cheapest ... and most likely to cause issues when it comes to conducting electricity and heat.
Anodizing and plating does little to impede the flow of electricity and heat. Standards and best-practices for marine low voltage (12-48 volts) direct current circuits is tin-plated copper wires.
I'm not sure about phosphate treatment. Next time I'm doing phosphate treatment, I'll do an experiment to see how much it insulates, if at all. (If I remember.)
