Extension Cords: Gauge, Length and the Mistakes That Cause Fires

Extension cord fires cause thousands of home fires every year. Most are preventable by matching the cord to the load. Here is what you need to know.

AWG gauge — thicker is safer

AWG (American Wire Gauge) measures wire thickness. Lower numbers mean thicker wire and higher ampacity: - **16 AWG**: Up to 13A — lamps, phone chargers, low-draw devices - **14 AWG**: Up to 15A — most household appliances, power tools - **12 AWG**: Up to 20A — high-draw tools, space heaters, air compressors - **10 AWG**: 20A+ — heavy equipment

Never use a cord thinner than the device's rated amperage.

Length affects capacity

The longer an extension cord, the more voltage drop it creates. For high-draw tools, use the shortest cord that reaches — or step up one gauge to compensate. A 100-foot 16 AWG cord is not suitable for a table saw that a 25-foot 16 AWG cord might handle.

Indoor vs. outdoor ratings

Outdoor extension cords are insulated with weather-resistant jackets and rated for direct sunlight and moisture (look for "W" in the cord designation, such as SJTW). Never use an indoor extension cord outside.

Three-prong vs. two-prong

Three-prong cords provide grounding — essential for tools and appliances with metal housings. Two-prong cords are fine for double-insulated devices. When in doubt, use three-prong.

What never to do

Never run extension cords under rugs (heat cannot escape), daisy-chain multiple cords, or use a cord rated for less amperage than the device demands. Never use extension cords as permanent wiring — they are a temporary solution.

Before you buy

Check the amperage rating of every device you plan to run, choose the appropriate AWG, and buy the shortest cord that reaches. Verify UL listing on the label.