I have replaced so many of those red and black cords Doc I could puke.
Pretty sure it's a crappy connections in the female side of the cord corroding, and a not so good grade of copper inside them - both connects and runs.
I don't buy their current draw ratings as a nominal rating - designed for that amp draw at short intervals off and on, not for 5 days contiguously. Even a consistent 10-11 amp of draw on the 50' / 100' the insulation shrinks up due to heat on the wires. 8-10 months and I am tossing them. On the other hand - the yellow guys from lowes, they are stuuupid expensive - but I don't have those issues, plus both ends have the lights.
I have gone to the utilitech pro 10/3 gauge, 20A, 100' runs, and hacked off the female end and wired a 4 way outdoor box on the end. I'll connect them to the little mytee converter boxes. Sets come as 2 units, gray cord/black cord. Black cord hits any 220 plug (dryer, range) I'll pull off the old style gray plug and leave exposed wire to connect directly to the panel. 2 boxes/connects, 4 cords = 80 amp on tap, enough to power just about any resi job.
As soon as I have a free $100k to burn - I'm getting all new AM's, the PC low amp fans. 10 on high per 15 amp circuit. Should remove about 75% of the cord games on jobs.