Extension Cord Sizing Guide: AWG, Amperage & Distance for Contractors (2026)
Mar 21, 2026
Using an undersized extension cord on a jobsite is a fire hazard and an OSHA violation. This guide covers wire gauge selection, amperage ratings by length, and OSHA requirements.
Wire Gauge and Amperage by Length
| AWG | 25 ft | 50 ft | 75 ft | 100 ft |
|---|---|---|---|---|
| 16 AWG | 13A | 10A | 7A | 5A |
| 14 AWG | 15A | 13A | 10A | 7A |
| 12 AWG | 20A | 15A | 13A | 10A |
| 10 AWG | 20A | 20A | 15A | 15A |
These ratings assume 3% maximum voltage drop.
Cord Jacket Types
SJTW — Standard thermoplastic, water-resistant. Most common for general indoor/outdoor use.
SJOW — Oil-resistant. Required for industrial environments with oils or solvents.
SOOW — Heavy-duty, oil-resistant, extra flexible. The premium choice for construction sites.
OSHA Requirements
OSHA 1926.405(a)(2) requires all extension cords on construction sites to be three-wire grounded, rated for hard usage, and GFCI-protected in wet locations. Damaged cords must be removed immediately.
