Extension Cord Terms

Demystifying a common household tool

An extension cord (also known as a power extender, extension lead, or extension cable) serves to connect appliances to inaccessible outlets or distant power sources. Composed of a length of flexible electrical power cable (flex), a unit features a plug on one end and one or more sockets on the other end. Used almost exclusively to connect devices to main (household AC) power, extension cords have been used for as long as electricity has been prominent in residential homes.

Bells and whistles galore

Compared to earlier models, today’s extension cords come with a number of advanced features: polarized plugs and receptacles, grounded terminals, “power-on” indicators, fusible links, and residual-current devices (also known as a ground-fault circuit interrupter or GFCI). In general, heavier extension cords contain a greater thickness and density of wires inside, as well as the appropriate amount of shielding. Larger jobs (say a cord to power a refrigerator, versus a cord being used for a hairdryer) require larger, thicker cords. Specifically designed cords can service yards, wet areas, or places exposed to intense, prolonged direct sunlight, but make sure the cord you choose has been certified safe for that use.

Safety standards

Since domestic voltage runs at 110 volts (V) in the United States, the National Electrical Code (NEC) prohibits the use of extension cords in a 20 A circuit unless they are of 16 AWG or larger (for example, 14 AWG or 12 AWG). Gauge is a measure of the diameter of the conductor (the thickness of the cable). The gauge is based on the American Wire Gauge (AWG) System, in which the larger the wire, the smaller the AWG number. For example, a 12-gauge wire is larger – and can power larger wattage appliances – than a 14-gauge wire.

The NEC also prohibits the use of extension cords where attached to building surfaces; concealed inside walls, floors, or ceilings; or where run willy-nilly through holes or other openings in structures (such as doors and windows). Cords run across the floor should be covered with a suitable device to protect them from physical damage.

Different forms, same function

An extension reel is an extension lead that rolls up, usually into the socket end, for convenient storage and to prevent people from tripping over excess lengths of cord. Some extension reels contain more than one socket, so that one length of heavy cord can service more than one appliance.

A power strip is a block on the end of a power cable with a number of sockets (usually three or more), often arranged in a line. A power strip functions in the same manner as an extension cord, but generally contains a shut off switch and surge protector.

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