I've got a Henry hoover, well, a 'Nuvac' to be precise. The power cable is twelve miles long and wraps around his head. If I'm just like, hoovering a rug, do I really need to completely unwind all this? Or just pull out what I need?
I've got a weird feeling that you're not supposed to use appliances with a coiled power cable for some unknown reason. False memory? Or one of those 'you might die one time in a million' things?
The heat built up during the short time you're vacuuming won't cause any issues. The wattage means it's only pulling approx 3 amps, which isn't enough to trouble the flex as 0.75mm2 is rated at 6A. You'll probably cause more of a safety issue by having the twelve miles of flex looped around your ankles.
Just pull out what you need.
IAAE
There is some general advice that wind up extension cords should be completely unwound before use - because the resistance in the wire causes some heat generation and thus could result in overheating. Personally I've never bothered if it was for a small job and have never detected any warming of cables. If you were leaving something plugged in for many hours or using a very high power draw device it might matter. I'm guessing a hoover is <750W and gets used for 15 minutes at a time so I'd certainly not bother - I've never noticed others doing so either. If it does get hot and smokey you are right there to act on it.
There is some general advice that wind up extension cords should be completely unwound before use
My extension cord is marked for two ratings, just googled it to check:
Max. Power Unwound (W) 3120 W
Max. Power Wound (W) 720 W
So you can see the drop off. It’s partly caused by trapping the heat that’s caused by resistive losses in the cable, I think there’s also an element of inductive losses increasing.