Yes, you will have double heat output due to twice the resistance which causes twice the voltage drop and more or less the same current. But this heat output is spread across twice as much wire, so unless the extension cables are coiled together on the ground each will heat up the same amount as a single one would.
fmstrat@lemmy.nowsci.com 5 weeks ago
These changes are not linear with extension cords, as the gauge variance is less than changes in length. 100% longer doesn’t mean 100% thicker. Also the heat does not just occur in the wire. Whatever is at the end of that cord has to work harder due to the voltage drop, and harder means hotter.