Yep, but copper is also supposed to be more efficient than tin (wich isn't really a good way to transmit power lol ^^) ... But we don't care. Does optic fiber conducts electricity ? It could (in the future ^^) conducts energy, but it would need a converter Light-Electricity ...
I've just suggested more cable because I'm bored of the "Tin for green gens, copper for small setup, opticfiber for long distance". How are you supposed to do if you haven't diamond enough to spend it to power only one machine but don't want extreme losses ?
That's why I've suggested one cable for each thing lacking in IC², to me.
the Glass fiber cables have a silver line in them (assuming you use that recipe) which is a very good conductor. The main issue i have is the uselessness of EV cables, which theoretically should have the lowest power loss, hence my suggestion for an aluminium cable which operates best at HV or EV (preferably in the 2048-8196 range) with extremely low loss, but needing to be uninsulated, therefore will electrocute anyone who gets too close.
Edit: on the iron topic:
if you double the voltage irl, this will half the current, and quarter the power loss for the same resistance.
So, if you quadruple the voltage (512 - 2048 ), this will quarter the current (ie 1/4 the number of packets), so, if using RL mechanics, would result in 1/16 the power loss for the same resistance, so using something with 10x the resistance, and still get less power loss (10/16, or at least should).