Ok, short lesson about cords, particularly when dealing with heavy electric loads.
Length matters, but not as much as people think...
Ok, mind back out of the gutter? Good!
If you decide to use an extension cord to charge lets say an EV you should know a few things.
1. It's not recommended for good reasons
2. If you're ignoring that recommendation you should fully understand what you are doing
There's a lot of reasons they recommend not using extension cords but there is indeed a safer way to use them. I'll point out some of the biggest hurdles but the real answer is always to set things up so you don't need an extension cord.
Gauge matters more than length. Gauge is the thickness of the wire and has a direct effect on how quick and how much the wire heats up for a given load.
Most "heavy duty" orange cords are 16 gauge. These are ok for light loads and some short use on some heavier loads but they should be avoided for most power hungry equipment and NEVER used for EV charging. If you must use them you should derate your charge to 8 amps or less.
Charging an EV should ideally be done on a 12 gauge or better yet a 10 gauge. When it comes to gauge you're better off with a 100 ft 10 gauge than you are with a 10 foot 16 gauge.
There are other critical factors
-check outlet condition with a two prong plug and see if it holds tightly, good resistance plugging and unplugging, not lose.
-Never use any plug with a broken off ground lug
-Never leave a cord wound up, piled, or in any state that traps heat.
-Check for voltage drop if possible through your charge unit or vehicle screen
-Use high safety devices like the Tesla universal mobile connector that check plug temperature and voltage drop (obviously temp check would only be at the connector plug)
Electrical safety is way more serious than people take it. It's very safe when done proper and very deadly when not. I'm always happy to answer questions if you have them.
Be safe out there!