another one is about coiling power cords,
now i realise this would form some level of inductance, but being how the neutral is next to active, inside each individual wire, should it not effectivly cancel it out (current in cancelled out by current out) or atleast make it negligible
now i know the other factor is temperature, but for a full 10A load, the wire size has to be AWG 10 (2.5mm^2) (1 milli ohm per foot/ 3.3 milli per meter) which for copper wires is only 0.33W per meter of wire heat, which even if bundled up, comes to only 3.3W of heat for the normal 5m leads, (nuetral is also a wire producing heat)
and ok, i'll do the math for say the shitty chinese leads that use only 1.5mm^2 wire (AWG 14), its 8.3 milli ohm per meter, it comes to 0.83W per meter, and this would be more likely to have propigated the story, as for the norm 5m lead, comes to 8.3W,
please note that the math was based upon copper wires under the australian standards, where only a 10 degree rise is allowed, and the chinese leads sometimes use the 35 degree rise standard,