So a standard cable needs to be chipped to show its rating to the device, its not that the device can pull what it wants or can get, but the cable itself tells it what it can supply. Extension cables can’t do that, because it doesn’t know what it’s plugged into, and that would be if they even bothered to put a chip in. They instead piggy back off the chip for the main cable. The problem comes when you you have a 240 watt cable hooked up to a cheap 120 watt cable, with the device being told it can push 240, and starts to super heat the extension cable