The Differences Between Indoor & Outdoor Extension Cords

Extension cords are the perfect solution when you need to power a device whose cord doesn't reach an outlet. However, indoor extension cords are very different from outdoor extension cords, and the two should not be confused. An outdoor extension cord can be used indoors, but you should never use an indoor extension cord for outdoor tasks. Knowing the difference indoor and outdoor cords will help you eliminate safety hazards.

Yellow electric wire extension cord on the reel
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The Differences Between Indoor & Outdoor Extension Cords

Insulation

The main difference between indoor and outdoor extension cords is the insulation used in their construction. Indoor extension cords do not have the same materials and protective insulation as outdoor extension cords do. Outdoor cords are made with durable insulation to protect against moisture and temperature changes. Sunlight can also break down the insulation used for indoor extension cords, but outdoor extension cords use a special material to protect against light damage. Outdoor extension cords are also constructed to prevent damage from chemicals, such as oil.

Gauge

The gauge of an extension cord is determined by the size or diameter of the conducting wires inside. Larger-gauge conducting wire allows more current to flow through the extension cord, which is required at greater lengths and for different pieces of equipment. Indoor extension cords rarely come in lengths longer than 25 feet, while outdoor extension cords come in lengths up to 150 feet or more. You will need the proper combination of gauge and distance specifications to safely power your appliances.

To power a leaf blower, for instance, you'll need a 16-gauge light-duty cord within 50 feet of an outlet. An indoor table lamp will need an 18-gauge cord specified for up to 25 feet. A circular saw requires a 12-gauge, heavy-duty outdoor extension cord for up to 100 feet. An indoor vacuum can use a common 16-gauge indoor extension cord.

Plug Type

Another difference between indoor and outdoor extension cords is the plug type used. Many indoor extension cords have a two-prong plug, and outdoor extension cords come with a three-prong plug. The third prong on the extension cord is a grounding wire that reduces the risk of electrical shock or fire. A two-prong extension cord is generally used on lamps or small appliances found indoors. A three-prong plug is only used with an outlet that has a ground slot. Combining a three-prong-plug extension cord with a two-prong-plug extension cord can be hazardous.

Amperage

Amperage differs from appliance to appliance. Indoor extension cords generally have a lower amperage rating than an outdoor extension cord, since outdoor devices require more amps than indoor appliances. For instance, whereas a lamp utilizes approximately half an amp, a leaf blower can use up to 12 amps. Most indoor extension cords would be unable to accommodate the amperage needs of a leaf blower.

Ground Fault Circuit Interrupter Extensions

A ground fault circuit interrupter extension can make your outdoor appliance use even safer. A GFCI is a circuit breaker designed to automatically shut off if it senses that power is flowing through something it should not, such as water or a person. Use of a GFCI along with your outdoor extension cords is a smart move. Be sure to plug the GFCI directly into your outlet, and then plug in your outdoor extension cord. Never plug the cord in first!

Selecting Cords

Before purchasing an extension cord, you need to take several factors into consideration, including the environment the extension cord will be utilized in and the power requirements. The indoor extension cord is generally used for small electrical devices such as household appliances, lamps or computer equipment, while the outdoor extension cord is used for greater lengths and higher amperage and voltage requirements, and requires protection from the environmental conditions. All extension cords come with information about length, amperage ratings, voltage ratings and whether the cord is intended for indoor use, outdoor use or both.