There's nothing wrong with that provided it's not a job site OSHA might
visit. The hardest part of making an extension cord like that would be
finding 10ga male and female ends. If they are rated for 12ga then the
250' of wire between the two might as well be 12ga.

Dan


I disagree. What he would be doing is effectively reducing the resistance of
the 250' length of the circuit. Since he's only running a 20A circuit, the
connectors wouldn't factor in as long as they are rated for 20A. His idea of
using larger guage wire would result in less voltage loss, and higher
capacity. Much less likely to overload and catch fire, especially if the
wire gets damaged in any way (as often happens on a construction site). Also
much better for electric motors. Very good idea for a 250' circuit.

You could do the same thing with a garden hose- using same size male and
female couplers on the ends as smaller hose, but increasing the diameter of
the hose will result in higher water pressure over a given distance.