Extension Cord
I plug in my trailer a couple of days before a trip so we can stock the refrigerator/freezer. The trailer is a 30 amp. system. I run an extension cord from a regular house outlet to the trailer usin...
Forum Discussion
Why do the cords need to be unwound...
Two primary reasons, though one does not apply all that well to 30 amp cords.
First: All wires have multiple current ratings,, ONE of them is "Free Air"
Another is "Coiled" and yet another is "in a wall" This has to do with how well the wire can cool off when current heats it up. Somewhere I once saw a chart fo the coiled capacity but frankly, that was long ago. With the wires in a coil air does not circulate around the cable as well and it gets hotter.
Second is induction.. Coils offer "inductive" resistance (R sub j if I'm not mistaken, is the symbol) and like regular resistance I^2 R applies.. If you have one ohm of Rsub J and 20 amps, that's 400 watts of HEAT.
Two primary reasons, though one does not apply all that well to 30 amp cords.
First: All wires have multiple current ratings,, ONE of them is "Free Air"
Another is "Coiled" and yet another is "in a wall" This has to do with how well the wire can cool off when current heats it up. Somewhere I once saw a chart fo the coiled capacity but frankly, that was long ago. With the wires in a coil air does not circulate around the cable as well and it gets hotter.
Second is induction.. Coils offer "inductive" resistance (R sub j if I'm not mistaken, is the symbol) and like regular resistance I^2 R applies.. If you have one ohm of Rsub J and 20 amps, that's 400 watts of HEAT.
