A length of insulated wire with a plug at one end and a socket at the other, an extension cord comes in handy to connect an appliance, a power tool, or another electrical device to a power source beyond the reach of the item’s own cord. Yet helpful as they are, extension cords can be dangerous.
According to the Electrical Safety Foundation International (ESFI) about 3,300 home fires are started annually by extension cords, killing or injuring hundreds of people each year. These fires occur because of overheated wires, which happens when too much electrical current passes through wires that are inadequate for the job.
Replacing old extension cords can keep a home and its occupants safe. Read on for tips on selecting the best extension cord (or multiple cords) for indoor and outdoor use, and see why the following options are winners in their categories.
- BEST OVERALL: Iron Forge Cable 100 Foot Outdoor Extension Cord
- RUNNER UP: US Wire and Cable 74050, 50ft, Yellow
- BEST BUDGET: GE, Black, 3-Outlet Power Strip, 6 ft Extension Cord
- BEST STANDARD INDOOR: FIRMERST 1875W Low Profile 1Ft Extension Cord
- BEST SMART: TanTan Gosund Smart Power Strip
- BEST IN STYLE: Cordinate Designer 3-Outlet Extension Cord
- BEST FOR GENERATORS: Champion Power Equipment 25 ft. Extension Cord
- BEST FOR OUTDOORS: UltraPro, Black, GE 25 ft Extension, Indoor/Outdoor
What to Consider When Choosing the Best Extension Cord
Various factors go into choosing the best extension cord for a given space and situation: safety and intended use, gauge and power ratings, cord length and voltage, jacket strength, and plug and socket type. In addition, shoppers may want to consider extra features like aesthetic appeal and lighted plug ends.
The main distinction among extension cords is indoor versus general/outdoor use. Outdoor and general use cords can be used indoors, but an indoor extension cord should never be used outdoors.
After establishing the correct type required, consider a few other elements as well. The environmental conditions surrounding cord use are highly important. Additionally, buyers should think about frequency of use and which appliances the cord will support.
- Light-duty cords can range from 25 to 100 feet, with a 1 to 13 amp power rating and a 16-gauge wire. They are well suited for Christmas lights, fans, and hedge trimmers.
- Medium-duty cords can range from 25 to 150 feet, with a 14 to 15 amp power rating and 14-gauge wire. They are useful for powering lawn mowers and power drills.
- Heavy-duty cords can range from 25 to 150 feet, with a 16 to 20 amp power rating and 10- or 12-gauge wire. A heavy-duty extension cord is designed for chain saws, shop vacs, and power-hungry tools and generators.
Many reliable extension cords also have a safety rating that’s certified by an independent testing agency, such as Underwriters Laboratories (UL), Intertek (ETL), or the Canadian Standards Association (CSA), to ensure the cord meets federal and international safety standards.
Wire gauge is the thickness or diameter of an extension cord’s internal wire. This thickness is measured by an American Wire Gauge (AWG) number: the smaller the number (000 to 40), the thicker the wire. For most home and outdoor use, look for a gauge rating between 10 and 18 AWG.
You can typically find a cord’s AWG number, or gauge rating, on the cord’s outer jacket—the layer of thermoplastic that surrounds and protects the electrical wires. Gauge rating is usually paired with the number of conducting wires inside the cord. For example, a 16/3 cord means a 16-gauge wire with three wires inside the cord.
In addition to the gauge rating, you’ll often see three numbers associated with an extension cord’s power capacity that indicate amps, volts, and watts. These values are crucial for safety—a cord can overheat and catch fire when an appliance is plugged into a cord with a comparatively insufficient power rating.
- Amperes (amps) measure the volume or amount of electricity flowing through the wire inside the cord.
- Voltage (volts) measures the pressure or resistance of this electric flow.
- Wattage (watts) measures the resulting power, indicated by volts multiplied by amps.
Cord Length and Voltage Drop
While some extension cords may be longer than 100 feet, those between 1 and 100 feet are the most helpful and popular for tasks in and around the home. Cord length also affects how much voltage is lost due to electrical resistance over distance. The longer the extension cord, the greater the voltage lost, a property called “voltage drop.”
To avoid voltage drop, use the shortest extension cord possible for a given task. Longer cords have less capacity (greater voltage drop) than shorter cords with the same gauge rating. For example, a 16-gauge extension cord less than 50 feet long can power an appliance up to 1,625 watts. In comparison, a 16-gauge cord longer than 50 feet will have less wattage and only power a 1,250-watt appliance.
Wire is an excellent conductor, but to function safely and effectively, it needs insulation. This feature is referred to as a jacket.
Plastic or woven nylon is used to cover indoor extension cords. Heavy-duty plastics, rubber, and vinyl often coat the electrical wires in outdoor extension cords. These durable materials protect the wire from environmental exposure, electrical leakage, and overheating.
The strength, material, and purpose of the cord jacket are designated by different letters. You will often see a combination of these letters printed on the jacket itself. Here are the most common letters associated with indoor and outdoor extension cords:
- S – Indicates a flexible cord designed for general use.
- W – Indicates the cord rated for outdoor use.
- J – Indicates a cord with a standard 300 voltage insulation. If there is no J in the designation, the cord has thicker 600-volt insulation for heavier use.
- P – Indicates parallel wire construction, used in air conditioner cords and household extension cords.
- T – Indicates the cord jacket is made from vinyl thermoplastic.
- E – Indicates the cord jacket is made from thermoplastic elastomer rubber (TPE).
- O – Indicates the cord is oil resistant.
Plug and Socket Type
An extension cord plug may have two or three prongs. The third prong means the cord is “grounded,” providing an additional path for electrical currents and contributing to overall safety.
The ground pin (third prong) is an essential safety feature of heavier duty extension cords, and users should never remove or bypass it in any way. Grounded (three-pronged) extension cords should be used with larger appliances.
The socket is the part of the extension cord into which you plug appliances. This strip may contain multiple sockets (for two- or three-prong plugs) to power up multiple appliances, provided you don’t go over the wattage (power rating) on the cord’s label.
Note that you can insert a two-pronged plug into a three-slotted socket, but never the reverse. Also, always use an extension cord with three-pronged sockets with appliances that have three-pronged plug ends.
Several standout features may contribute to cord usefulness and safety, and if an extension cord is intended for indoor use, its appearance may play a role in your decision. Additional features may include:
- A built-in ground fault circuit interrupter (GFCI) is a safety device that automatically shuts down power to the extension cord in the event of a ground fault or short circuit.
- Lighted plug ends illuminate to indicate when the cord is powered. It is also a safety feature of outdoor extension cords for use in darker conditions.
- A connector box fits around both the extension cord plug and the plug on the connected electrical device to keep them from pulling apart.
- A locking socket is a mechanism built into the extension cord socket that keeps the device and cord securely connected.
- USB ports are a great extra feature on a power strip or extension cord in a home office. A phone or other mobile device can charge while powering a laptop or monitor.
- Embedded smart technology allows the integration of home Wi-Fi. Once connected, users can control plugs and ports by using the timer or through an app when away from home. A smart power strip can also offer surge protection.
Having more than one extension cord or surge protector throughout the house can look unattractive, especially if they all stick out like a sore thumb. Luckily, a variety of cord colors are available to match existing decor. You can also find wire cable covered in a braided fabric instead of the traditional plastic, which adds to a more pleasing aesthetic. Some cords come in bright colors for visibility—ideal for an outdoor extension cord—to prevent tripping and other accidents.
Our Top Picks
These top picks were selected according to the criteria detailed above. They include products in a variety of categories to suit unique needs. Read on to discover some of the best extension cords on the market today for safe power indoors or outdoors.
This all-purpose extension cord from Iron Forge Cable, designed for both indoor and outdoor use, features a flexible, green vinyl jacket that’s water-resistant and protects against moisture, abrasion, and sunlight. The 16-gauge wire has a power rating of 10 amps, 125 volts, and 1,250 watts, and the cords are UL listed for safety.
The 100-foot extension cord boasts reinforced blades to prevent bending or breaking. This extension cord can also handle most medium to heavy-duty applications, from running a lawnmower to powering string lights.
- Waterproof, UV-protecting, and flexible vinyl jacket
- Durable 12-gauge wire
- UL listed for safety
- Suitable for indoor and outdoor use
Prevent tripping over the cord and other accidents with this bright yellow extension cord from US Wire and Cable. The 50-foot cord stands out outdoors or among tools in a garage or workshop. It also includes an SJTW vinyl outer jacket that won’t split or crack in colder temperatures as low as -35 degrees Fahrenheit.
The 12-gauge wire features 15 amps, 125 volts, and 1,875 watts of power, as well as a lighted female plug that identifies when the cord is in use.
- Temperature-resistant vinyl jacket
- Illuminated plug indicates on/off status
- Bright yellow color is clearly visible for safety
- Color will stand out against surroundings
Make sure no one sticks little fingers or slim objects inside any of the receptacles of this three-outlet extension cord from GE. It boasts twist-to-close safety outlet covers that help prevent injuries. The 16-gauge cable also boasts power ratings of 13 amps, 125 volts, and 1,625 watts and is UL certified.
For use indoors, users can add three outlets up to 6 feet from the nearest plug with this inexpensive extension cord, and the two-prong plug features strain relief to reduce fraying. The cord is ideal for home offices, workshops, or garages.
- Affordable option
- UL listed with a tamper guard for safety
- Includes 3 outlets
- Available in multiple colorways
- Not suitable for outdoor use
- 6-foot length is short compared to other cords
FIRMERST’s 1-foot extension cord has a 14 AWG gauge rating and a power capacity of 15 amps, 125 volts, and 1,875 watts. The cord is UL certified and temperature resistant up to 167 degrees Fahrenheit. Plus, the flat plug design is well suited for the tight spaces between outlets and furniture, bookshelves, and desks.
The thick wires are encased in heavy-duty plastic that is sturdy but flexible. The wires can handle more amperage and wattage—with less chance of overheating compared to similar products with thinner 16 or 18 AWG wires.
- Set includes three extension cords
- UL certified with temperature resistance
- Thick, sturdy wire
- Low profile design works well for tight spaces
- Limited 1-foot reach
- Not recommended for outdoor use
Connect this smart power strip to a 2.4 GHz Wi-Fi router and gain full access to connected devices through voice commands, Amazon Alexa and Google Home, scheduled timers, and a free companion app. The three power outlets are controlled separately, and the USB ports are managed together.
The total output for the USB ports is 3.1 amps, enough to charge phones, tablets, and other USB devices simultaneously. The black extension cord supports 100 to 240 volts and has a maximum load of 10 amps. It features both surge protection and overload protection. The circuit breaker automatically breaks off power when the cord exceeds the threshold-eliminating damage to connected devices.
- Set includes 3 power outlets and 3 USB ports
- Compatible with Alexa and Google Home; controllable with a smartphone and voice commands
- Built-in overload and surge protection
- Requires a 2.4 GHz network
- Not suitable for outdoor use
Let’s face it: Most extension cords offer little in the way of home decor. Fortunately, the Cordinate cord is the exception. Rather than a thick plastic jacket, the 8-foot cord is wrapped in woven fabric to blend with its surroundings while preventing bends and tangles. It’s available in 12 colors and chevron-pattern designs to match various decor color schemes.
With a power capacity of 13 amps, 125 volts, and 1,625 watts, this cord is ideal for lamps, fans, and small household appliances. For added safety and to prevent electrical shocks, it also features slide-to-lock covers for each of the three polarized outlets. Additionally, the cord boasts a flat design that’s useful for rooms with limited space.
- Includes 3 outlets
- Built-in slide-to-lock covers
- Compact design
- Available in 12 colorways
- Not suitable for outdoor use
- Outlets only support 2-prong cords
This 25-foot extension cord from Champion Power Equipment boasts 30 amps, 125 volts, and 3,750 watts of power. It extends a single 30-amp locking outlet 25 feet away from the generator and provides three 15-amp outlets at a safe distance from the generator exhaust.
The service-grade extension cord is abrasion- and weather-resistant and comes with dust covers to keep the outlets clean and clear when not in use. It is also cold and heat resistant with a 10-gauge wire that remains flexible in extreme temperatures.
- High power output
- UL listed for safety
- Resists abrasion, weather, and temperature
- Includes a 30-amp locking outlet and 10-gauge wire
This UL-listed extension cord includes three power outlets and a host of features to meet power-extending needs for outdoor spaces. It has a power capacity of 13 amps, 125 volts, and 1,625 watts that’s especially suitable for lighting. The cord features molded plugs and is double insulated for enhanced durability, longevity, and safety.
- Affordable choice
- Includes 3 outlets
- Double insulated for safety
- Durable molded plugs
- Available in multiple colorways
- May not be suitable for heavy-duty use
For ample power supply, UL-listed safety, and indoor/outdoor flexibility, we recommend the Iron Forge Cable extension cord as our top pick. Those who need more power capability for a home office, countertop, or entertainment center would be better off using the GE cord, featuring 3 outlets and multiple color choices.
How We Chose the Best Extension Cords
Extension cords make power more accessible to electronics indoors and out, and key factors go into the top models; in particular, wattage capability, safety, and durable construction. The featured products reflect different lengths, colors, and price points to accommodate specific user needs.
Many of the above options are made with insulated or vinyl jacketed cord for use in different weather and temperature conditions. Most units are UL listed for safety, and some include a surge protection or a temperature regulator. Certain high-end options are even compatible with smart home systems and stand out with other useful features, like LED lights and USB ports.
Safety Tips for Using Extension Cords
It’s essential to follow some simple safety tips to ensure you and your loved ones remain safe when using extension cords.
- Don’t remove the grounding pin to fit it into a two-prong outlet.
- Make sure to use the correct rating.
- Check to see if it’s intended for indoor or outdoor use.
- Match the wattage rating to the appliance or tool—don’t use a lower rating.
- Stop using the cord if it feels hot to the touch.
- Never run an extension cord under furniture or rugs.
- Steer clear of plugging in multiple appliances to one cord.
- Don’t coil or bend when in use.
- Don’t plug two or more together.
- Refrain from nailing, taping, or stapling to the floor.
- Shield receptacles with childproof covers when not in use.
- Use polarized or three-prong plug extension cords.
- Do not run cords through doorways, walls, floors, or ceilings.
Some overload warning signs to look out for when using an extension cord:
- It is hot to the touch.
- A colored wire from the inside of the cord is visible.
- A smell of hot plastic or burning near an outlet or appliance.
- Blackness or burn marks near a power outlet, plug, or appliance.
- Broken or frayed plugs.
- A blown fuse or circuit breaker.
Q: What is the safest extension cord?
You can look for a safety rating on the cord or its packaging from UL, ETL, or CSA to ensure the cord meets federal and international safety standards. It’s also important to make sure the extension cord matches the intended use, including the wire gauge rating, wattage, and suitability for indoor versus outdoor environments. Remember also to ensure the jacket strength matches the job purpose.
Q: Which is better, a 12- or 16-gauge extension cord?
The smaller the wire gauge, the thicker the wire cable. A 10- to 12-gauge wire is considered a heavy-duty extension cord, a 14-gauge wire is a medium-duty cord, and a 16-gauge wire is a light-duty cord.
Q: What is the heaviest duty extension cord?
A 10- to 12-gauge wire is considered a heavy-duty extension cord, a 14-gauge wire is a medium-duty cord, and a 16-gauge wire is a light-duty cord.