I bought a 10/3 guage cord. It still gets slightly warm, but not nearly as the 12 guage. I feel that it's safe.
My “lesson learned” horror story... I was trying to warm up a hangar using two space heaters. I plugged them into a cord reel extension cord and seemed good to go. Until the power went out in the hangar - tripped breaker that would not reset. Reason? The insulation on the portion of the extension cord still on the reel had melted, shorting the whole mess together. If I knew then what I know now...
Good story. And is exactly why back in post #19 I specifically stated that one of my qualifications for safe extension cord use is “fully uncoiled”. Retractable or wrapped/bundled extension cords are not an acceptable alternative. Cooled cords can’t dissipate heat and will melt themselves into a mass every time when asked to carry a big load... Uncoiled cords is one of those rules of electricity that simply must be followed...
Is coiled and cooled acceptable? We always “coiled” excess cable into a figure 8. Never had to put it on ice.