What gauge extension cord should I use for power tools and heavy equipment?

Use 12-gauge for real work — it handles 20 amps and is safe for power tools, shop vacs, and air compressors. 14-gauge is fine for lights and small household stuff under 15 amps, but can trip breakers or risk fire with high-draw tools. For cords over 50 feet, bump up to 10-gauge to avoid voltage drop.