How to Choose Extension Cords Buying Guide
Extension cords kill people. Not often, but the cause is always the same: wrong gauge for the load, indoor cord used outdoors, or a cord run under a rug where heat can't escape. The right cord is a boring purchase that lasts 20 years. The wrong one is a fire hazard. Here's how to get it right.
Wire Gauge: The Single Most Important Spec
Wire gauge (AWG — American Wire Gauge) determines how much current a cord safely handles. Lower AWG number = thicker wire = more capacity. The number is usually printed on the cord's jacket.
16 AWG: Handles up to 13 amps (1,560 watts). Suitable for: lamps, phone/laptop chargers, small fans, clock radios. NOT suitable for: anything with a heating element, power tools, or appliances over 500W. Most cheap extension cords sold at dollar stores and convenience stores are 16 AWG — they're fine for phone chargers, dangerous for anything power-hungry.
14 AWG: Handles up to 15 amps (1,800 watts). Suitable for: most household appliances including toasters, coffee makers, window fans, and desktop computers. The most versatile gauge for indoor general use. A $12–$20 14-gauge cord from AmazonBasics, GE, or Southwire covers 90% of indoor needs.
12 AWG: Handles up to 20 amps (2,400 watts). Suitable for: power tools (drills, circular saws, jigsaws), space heaters, portable air conditioners, and shop vacuums. Also the correct gauge for outdoor cords with multiple outlets. Visibly thicker and heavier than 14 AWG. Prices: $15–$40 depending on length.
10 AWG: Handles up to 30 amps. Used for heavy equipment, welders, and large power tools. Not a consumer purchase — sold at electrical supply stores.
How to check: The jacket usually reads "16/3", "14/3", or "12/3" — the first number is gauge, "/3" means three conductors (hot, neutral, ground). If it only says "/2," it has no ground wire — avoid for any grounded appliance.
Length and Voltage Drop
Every foot of extension cord adds resistance, which drops voltage. For sensitive electronics and precise power tools, this matters. Practical rules:
Under 25 feet: Negligible voltage drop for most applications. Use whatever length you need.
25–50 feet: Upgrade one gauge size from what you'd normally use. If a 16-gauge would work at 10 feet, use 14-gauge at 35 feet to compensate for resistance.
50–100 feet: Upgrade two gauge sizes. A 16-gauge at 75 feet can cause motors to overheat and electronics to malfunction. Use 12-gauge for anything beyond low-wattage lamps at this distance.
Over 100 feet: Use 10-gauge or run a dedicated outlet. Long extension cord runs are not a permanent solution for any high-draw appliance.
For outdoor tools and generators, buy the shortest cord that reaches — every extra foot is wasted money and resistance. Most people buy 100-foot cords "just in case" and then wonder why their power tool runs hot.
Indoor vs. Outdoor Ratings
Indoor extension cords have thin PVC jackets rated for interior temperatures and no UV exposure. Outdoor extension cords have thicker, weather-resistant jackets (often rubber or SJTW thermoplastic) that withstand moisture, UV radiation, and temperature swings from -40°F to 140°F.
Never use an indoor cord outdoors: The insulation cracks from UV and temperature cycling, exposing live wires. The three-prong plugs corrode from moisture. This is the most common extension cord safety violation. Outdoor cords cost $15–$35 and last 10+ years outside.
Outdoor cord indoors: Fine — the heavier insulation doesn't cause problems. If you buy one outdoor cord, it works in both places.
Look for these markings: "W" in the cord designation (e.g., SJTW) means weather-resistant. "Outdoor rated" on the packaging. Most orange extension cords are outdoor-rated; most white and beige cords are indoor only.
Wet location vs. damp location: Wet location (UL Type W) cords are fully waterproof — used for landscape lighting and permanently outdoor applications. Damp location (SJTW) handles rain and moisture but not submersion. For a backyard or patio, damp location is sufficient.
Number of Outlets and Power Strips vs Extension Cords
There's an important distinction between an extension cord (runs power to a different location) and a power strip (multiplies outlets at one location). They're sold side by side but serve different purposes:
Extension cord: One outlet at the end, or up to 3. Long and thin. Designed to move power 10–50 feet. Not designed to stay permanently connected — the heat generated by continuous load degrades the cord over time.
Power strip: Multiple outlets, usually 6–12. Short or no cord. Often has surge protection. Designed for desk setups, entertainment centers, and anywhere you need many outlets in one spot.
Surge protectors: A power strip with a metal oxide varistor that absorbs voltage spikes. Essential for TVs, computers, gaming consoles, and any electronics with sensitive components. A $15–$30 surge protector from APC or Belkin pays for itself when a lightning storm or utility surge comes through. Look for joule rating (1,000+ joules) and "UL Listed" — not just "surge protection" marketing language.
What not to do: Daisy-chain extension cords (plug one into another) — this violates UL certification and creates a fire hazard. Don't run cords under rugs — heat buildup from the load has no escape and degrades insulation. Don't use a single extension cord to power multiple high-draw appliances simultaneously.
Safety Labels to Verify Before Buying
UL Listed: The gold standard for extension cord safety in the US. Means the cord was independently tested against UL 817 standard. Look for the "UL" mark on the cord jacket itself — not just the packaging, which can be faked. If the cord has no UL listing, don't buy it.
ETL Listed: Intertek's equivalent to UL. Equally valid and tested to the same standards. Common on cords from hardware stores.
OSHA requirements: For any commercial or jobsite use, cords must be UL or ETL listed AND the right gauge for the load AND inspected regularly. Damaged cords (frayed insulation, cracked plugs, warm connectors) must be removed from service immediately.
Amperage and wattage labels: The cord itself should be stamped with its amperage rating. A 15A cord cannot safely run a 20A tool. When in doubt, go heavier gauge — a 12-gauge cord runs cool on light loads but a 16-gauge cord runs hot under heavy loads.
What We Recommend
General indoor use: 14-gauge, 25-foot indoor cord from AmazonBasics or GE ($12–$18). Covers 90% of household needs. Power tools and shop: 12-gauge, 25–50-foot outdoor-rated cord, orange jacket ($20–$35). AmazonBasics, Husky, and Southwire all make reliable versions. Outdoor landscaping: 12-gauge SJTW outdoor cord ($25–$40) from Conntek or Woods Industries. Computer and electronics desk: A surge protector with 6+ outlets and 1,000+ joule rating ($20–$35 from APC or Belkin) rather than an extension cord. See our power strip guide for full surge protector recommendations, and floor mats for protecting the area where cords run.