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For a 150-foot extension cord, use 14 AWG for light loads up to 7 amps, 12 AWG for typical household tools, and 10 AWG for heavy or continuous loads of 15 amps.
For the full breakdown, see our best 150 Foot Extension Cord guide.
Voltage drop is why long cords need heavier wire than short ones. A 15-amp tool that runs fine on a 25-foot cord can stall at the end of 150 feet of thin wire, because resistance over that distance steals voltage the motor needs. For a standard U.S. 120-volt household circuit, how to choose the right gauge for a 150 foot extension cord comes down to the amp rating stamped on the device’s nameplate.
What Gauge Should You Use At 150 Feet?
The rule for a full 150-foot run: step up the wire size as the amp draw climbs. The ranges below match the 150-foot guidance in the Electrical Safety Foundation International’s extension cord safety tips, plus published extension cord size charts.
- 14 AWG — roughly 1 to 7 amps. Plenty for lamps, phone chargers, radios, and small electronics. Call it light-duty only at this length.
- 12 AWG — roughly 8 to 10 amps. The common pick for typical household tools and yard gear: drills, hedge trimmers, mowers, and most shop equipment. One published chart extends this size to 12 amps at 150 feet.
- 10 AWG — roughly 11 to 15 amps. The safer choice for 15-amp circular saws, space heaters, air compressors, and any load that draws power continuously for a long stretch.
So the decision logic is short: read the amps, match the row, and when a device sits near the top of a range, move up one gauge instead of trusting the edge.
How To Match The Amp Draw To The Cord
Start with the nameplate. Every motor-driven tool or appliance carries a metal or printed sticker near