Extension lead

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CEE extension cable ring with plug and coupling, 400 V 16 A 6 h IP67

An extension line (also extension cord , extension cord , or short extension called) is a cable that can be connected when the length of the own connection cable of an electrical device is not sufficient, or other connection line.


The extension cord has a plug at one end and a coupling with the function of an extended socket at the other . The current then flows from the socket via the extension cable to the electrical device.

However, a power line (power cable ) must not be lengthened at will, as short-circuit detection by the fuse is no longer guaranteed due to the higher intrinsic resistance of a line that is too long and, under certain circumstances, there is a risk of fire and death for the user in the case of defective end devices. This applies in particular to the loop resistance of the protective conductor connection; it limits the cable length to the usual 50 m for cable reels, for example. If there is a high current flow through the cable, it is advisable to unroll the cable completely to prevent overheating (due to accumulated heat) or a cable fire.

A cable reel with extension cable for household use

Data transfer

The term extension cable not only refers to power cables, but also cables for data transmission , for example:

Since some electrical signals cannot be transmitted over any length of distance, extension cables are often subject to physical limits. For example, the maximum length for USB cable connections is 5 m, unless the transmitted signals are amplified via an intermediate amplifier.

See also

Web links

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