Wire Gauge (AWG)
Affiliate link — we may earn a commissionWire gauge measures the diameter of an electrical conductor using the American Wire Gauge (AWG) system. The scale runs backward: lower numbers mean thicker wire with higher ampacity. 14 AWG handles 15 amps, 12 AWG handles 20 amps, 10 AWG handles 30 amps. For extension cords, gauge and length together determine how much current the cord can deliver without voltage drop. A 100-foot 16-gauge cord loses enough voltage to brown out a 15-amp circular saw. A 100-foot 12-gauge cord delivers the same power cleanly. The wire gauge is printed on the cord jacket or on a tag near the plug.
Why It Matters
An undersized extension cord doesn't just run the tool slowly. It overheats the cord, which can melt the insulation and start a fire. It also starves the motor of voltage, which makes it pull more amps to compensate, creating a feedback loop. Match the cord gauge to the tool's amp draw and the cord length. For a 15-amp tool on a 50-foot cord, use 12-gauge minimum.