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Best Extension Cords

Updated April 2018
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BestReviews spends thousands of hours researching, analyzing, and testing products to recommend the best picks for most consumers. We only make money if you purchase a product through our links, and we never accept free products from manufacturers. Read more
BestReviews spends thousands of hours researching, analyzing, and testing products to recommend the best picks for most consumers. Read more
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We purchase every product we review with our own funds — we never accept anything from product manufacturers.

  • 67 Models Considered
  • 43 Hours Researched
  • 2 Experts Interviewed
  • 91 Consumers Consulted
  • Zero products received from manufacturers.

    We purchase every product we review with our own funds — we never accept anything from product manufacturers.

    Shopping guide for best extension cords

    Last Updated April 2018

    Most people have at least one extension cord in use in their home or business. Because these devices are so easy to use, you might be tempted to just grab one off the shelf, plug it in, and never give it a second thought. However, there are quite a few things to know about different extension cords. Having this knowledge will help you purchase a cord that not only meets your needs but is also safe to use.

    At BestReviews, we carefully researched extension cords and assessed customer feedback in order to find the market’s top offerings.  on the detailed research we perform in each product category. We talk to experts and assess customer feedback to give our readers all of the key information they need to make smart purchases.

    Understand that we never accept free samples from manufacturers. This allows you to feel confident that our selections and product reviews are unbiased. If you are ready to buy an extension cord, check our five top picks above. If you’d like to know more about extension cords, continue reading!

    Two flat prongs are standard on every extension cord plug. The round third prong is the grounding prong.

    What is an extension cord?

    Simply put, an extension cord is an electrical cord. When connected to the cord of an electrical device, the extension cord allows you to position the device farther from an electrical outlet than the device’s own cord would allow.

    You can find extension cords ranging in length from 6 to 100 feet or more. They also are available in different gauges to carry different levels of electrical power safely. But no matter how long or powerful extension cords may be, the basic interior components are all the same.

    Wires and insulation

    Inside the extension cord are copper or aluminum wires covered with colored insulation.

    • The black or red wire carries the power.

    • The white wire carries the current back to the source.

    • The green wire (or wire with no insulation) is the ground wire. You’ll find this wire in an extension cord with a three-prong plug.

    An indoor extension cord is usually white or brown. Outdoor cords are usually orange, red, green, or black.


    The jacket is the cover that you see on the exterior of the cord. If the jacketing on an extension cord is too thin, the cord could overheat, melt, and cause a fire.

    • Round: The jacket is round and thick on heavy-duty extension cords. Thick wires generate a lot of heat, and the thick jacket protects you and objects around the cord from this heat.

    • Flat: The jacket may have a flattish shape on a light-duty extension cord.

    Indoor extension cords have plastic jacketing, while outdoor cords usually have a waterproof, rubber-type jacket.

    Plugs and receptacles

    • One end of the extension cord has a two- or three-pronged plug.

    • The other end of the extension cord has a receptacle (the number of holes matches the number of prongs on the plug end).


    The length of the cord and the gauge together determine the safe power capacity of an extension cord.

    Staff  | BestReviews

    Extension cord designations

    Most extension cord manufacturers use a series of letters to designate the features of each cord. These letters appear in the name of the cord or in the specifications. For example, a common designation for a heavy-duty extension cord for home use is “SJTW,” which indicates a general cord made for outdoor use with standard insulation and a vinyl thermoplastic jacket.

    • E: Cord jacket made of thermoplastic elastomer rubber (TPE)

    • J: Cord with standard 300-voltage insulation

    • O: Cord jacket impervious to oil

    • P: Household cord with parallel wire construction

    • S: Cord for general use

    • T: Cord jacket made of vinyl thermoplastic.

    • UL: Cord certified by Underwriters Laboratories

    • W: Cord approved for outdoor use


    Some specialty extension cords have plugs for odd-shaped receptacles, such as those used in RVs.

    Staff  | BestReviews

    Understanding awg numbers

    When looking at extension cords, you’ll see the product’s American Wire Gauge (AWG) number printed on a tag or the cord itself. This number, for example 16/3, tells you the gauge of the wire in the extension cord (16) and the number of conducting wires inside the cord (3). Some extension cords only show the first number. You can figure out the number conducting wires in the cord by looking at the plug.

    • Gauge: Lower-gauge wire is thicker than higher-gauge wire. This means a wire with a lower gauge number can carry more electrical power safely than a wire with a higher number.

    • Conducting Wires: An extension cord has either two or three conducting wires. An extension cord with two conducting wires does not contain a grounding wire and has a two-pronged plug. An extension cord with three conducting wires has a grounding wire and a three-pronged plug.

    Don’t use an extension cord on an appliance that exceeds the cord’s maximum power capability. The cord could overheat and cause a fire.

    Outdoor extension cords

    An extension cord’s length and gauge help determine how much power it can carry safely. The longer the extension cord, the less power it can carry safely. Here are some common extension cord lengths and gauges, along with the suggested maximum amps to use with each type of outdoor extension cord.

    To run a device that needs 15 or fewer amps, you’ll need one of the following.

    • A 14- or 16-gauge cord of 25 or 50 feet.

    • A 12- or 14-gauge cord of 75 or 100 feet

    • A 10- or 12-gauge cord of 100 feet or more

    To run a device that needs 16 or more amps, you’ll need one of the following.

    • A 12-gauge or heavier extension cord of 25 or 50 feet

    • A 10-gauge or heavier extension cord of 75 or 100 feet

    It isn’t recommended that you use a cord longer than 100 feet.

    Extension cord prices

    Extension cords are available at many different price points. You can find good-quality extension cords for between $5 and $75. Look for the UL designation on any extension cord you buy. However, even a certified extension cord could fail if you overload it. In general, the price of an extension cord is determined by the following factors.

    • Length: Longer is more expensive than shorter.

    • Gauge: Lower-gauge (thicker) wires cost more than higher-gauge (thinner) wires.

    • Outdoor: Outdoor extension cords cost a little more than indoor cords.

    • Grounded Plugs: Cords with three-prong, grounded plugs cost more than two-prong cords.
    Electrical cords with smaller gauge numbers can safely carry more power than cords with larger gauge numbers.


    Q. Can I string multiple extension cords together?
    You can connect extension cords to each other safely as long as you don’t exceed the maximum load for each cord. This process works better if you connect two extension cords that have the same AWG rating. If you must connect extension cords, we suggest only using heavy-duty cords.

    Q. What are amps?
    An amp, short for ampere, is a unit of measure of electric current that flows through the wiring in any type of cord. Different sizes of wires will successfully carry different levels of amps. An extension cord is rated to be able to handle a certain number of amps based on its length and gauge.

    Q. What are some special features of extension cords?
    If you plan to use the extension cord in a harsh environment, you may want a product with special protections. For example, some extension cords are impervious to oil or can run outdoors in extreme temperatures. Some have non-standard plugs or receptacles that allow them to run certain appliances. And some have small lights in them, so you can tell at a glance if they’re working.

    Q. Why do some extension cords have two prongs and others have three prongs?
    The third prong in an extension cord serves as the connection to the grounding wire in the electrical outlet. A grounding wire greatly reduces the chance of a fire from an overloaded outlet. A grounding wire also reduces the possibility that you’ll receive an electric shock if the extension cord malfunctions.

    The team that worked on this review
    • Alice
      Web Producer
    • Bronwyn
    • Devangana
      Web Producer
    • Kyle
    • Melissa
      Senior Editor