Review on 30-Amp Generator Extension Cord (25 Feet) - NEMA L14-30P/L14-30R, 10 Gauge SJTW Locking Power Cord For Manual Transfer Switch, Portable Generators, Power Outage - 120/250-Volt 7500W - GearIT (25Ft) by Tonya Wolfe

I design power electronics for a living and since this complete cord costs less than the individual connectors and wire I was very skeptical it wouldn't burst into flames if run at anywhere close to its 30A rating. Well, color me surprised, because each pole measured between 12 to 16 milliohms from end to end, and since 10 feet of #10 wire will contribute about 10 milliohms itself, those were very good total resistance values. An average resistance of 14 mR will result in about 0.4V of drop at 30A, for a round-trip loss of about 0.8V, or 0.33% of 240V; far less than the max 1-2% drop recommended for an extension cord (that said, you'd be pushing up against that limit with a 30' or longer cord).Time will tell if the cord will hold up to actual use, but it at least made a very favorable first impression for me.