The nickname for an extension cord made to the film industry standard. Most often referred to a single 'hot' extension that is left lying around for occasional use.
1620px Extension Cord

The nickname for an extension cord made to the film industry standard. Most often referred to a single 'hot' extension that is left lying around for occasional use.

An extension cord, power extender, drop cord, or extension lead is a length of flexible electrical power cable (flex) with a plug on one end and one or more sockets on the other end (usually of the same type as the plug). The term usually refers to mains (household AC) extensions but is also used to refer to extensions for other types of cabling. If the plug and power outlet are of different types, the term "adapter cord" may be used. Most extension cords range from around two to thirty feet in length although they are made up to 300 feet in length.

The term "extension cord" has been in use since at least 1925.

Extension cords come in various colors, lengths, thicknesses and service duties. In general, the more power needed by the appliance, the thicker the cord needs be (meaning larger wires inside). Cords which will be used outdoors, in wet areas, around oils, or exposed to sunlight for long periods of time should be selected for such specific conditions. An extension reel is an extension lead that rolls up, usually into the socket end, which in some cases has more than one socket on it (often 2 or 4). Another type of extension reel hangs near the plug end and permits the user to draw the cord out by grasping the socket end.

Some extension cords also incorporate safety features such as a polarized plug and receptacle, grounded terminals, a "power-on" indicator, a fusible link, or even a residual-current device (also known as a ground-fault circuit interrupter or GFCI).

Some cords contain multiple female connectors in close proximity of one another; others have female connectors spaced along the length of the cord. Cords generally contain either grounded or ungrounded connectors. While a grounded male connector can be forced into an ungrounded female socket, this is unsafe.


A power strip with power indicator and individual switches for each socket (UK)

A power strip is a block on the end of a power cable with a number of sockets (usually 3 or more), often arranged in a line. This term is also used to refer to the whole unit of a short extension cord terminating in a power strip.

A removable power cord is similar but much shorter, and is designed to connect an appliance to a mains outlet. The female end mates with an appliance inlet.


Cords running across the floor should be covered with a suitable device to protect them from physical damage. However, they should never be covered with a rug or carpet, as this can produce a serious fire hazard.

To avoid the need for rolling-up excess length, using an extension reel or for cutting the cord to size, extension cords are sold in prefabricated lengths of 1 to 150 feet (30 cm to 45 m). Every foot of cord increases the electrical resistance, in turn decreasing the power the cord can deliver. Therefore, the longer the cord, the larger the diameter of the conductors need be to minimise voltage drop (wire gauge numbers are smaller for larger diameter wire). Because of this, it is best to use a cord that's exactly as long as needed and no more.

An extension reel can only carry full rated current when completely extended. This is because the portion of cord on the reel is not exposed to air causing the loss power, (the result of its series resistance), not to dissipate. An extension cord that is in use while coiled up or coiled in a reel can be a serious shock and fire hazard. The heat produced from the resistance cannot dissipate and is instead trapped between the tightly coiled cable, leading to the a fire or shock. Additionally, the ESFI recommends to never use an extension cord that is covered by a rug or blanket, or that is run through a ceiling or wall, since the heat may not be able to dissipate appropriately.

Key Terms

extension cord
extension cords
extension lead
extension reel
feet length

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Last modified on July 17 2019
Content adapted from Wikipedia
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