Editing Extension cord (section)

==Signal cable extenders==
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{{Main|USB}}
[[File:USB extender cable.jpg|thumb|USB extender cable (passive type; non-standard)]]

'''Extension cords''' sometimes refer to cables that add to the length of signal transmission cables or combined signal/electrical cables (for example, [[Universal Serial Bus|USB]] cables). They are more likely to be called "extenders" or "extender cables" or "cable extenders". Such extenders have one male and one female connector.

Passive USB extender cables do not meet the USB standards and thus are forbidden to carry the USB logo. The only cable structure recognized by the official USB standards is one with either a type A plug or a type C plug on one end, and either a type B plug or a type C plug on the other end (adapters with a type C plug and a type A or type B socket are also allowed, while adapters with a type C socket and a type A or type B plug or socket are explicitly not allowed<ref>{{cite tech report|title=Universal Serial Bus Type-C Cable and Connector Specification Release 2.0|type=Specification|date=August 2019|publisher=[[USB Implementers Forum]]|page=32|quote=USB Type-C receptacle to USB legacy adapters are explicitly not defined or allowed. Such adapters would allow many invalid and potentially unsafe cable connections to be constructed by users.}}</ref>). This restriction is intended to prevent cable lengths greater than the maximum allowed by the USB standard from being assembled and to avoid an accumulation of resistance in the connections exceeding the design limits of USB, in order to ensure consistent plug-and-play operation of the USB system without the need for users to calculate cable lengths or enforce technical rules.

The intention of USB is to make sure any standard-compliant cable can be used to connect any two compatible devices, and the connection will work, without question.  To this end, the USB standard limits the maximum length of any compliant (and thus logo-bearing) USB cable (to about 15 feet). For a longer cable length, a USB hub is required. Despite being nonstandard, these extender cables are readily available from many sources.

Another class of USB extenders are actually USB hubs with a length of cable permanently attached.  These do comply with the USB standard, if not more than a limited number of them are connected together.  However, they require power from the USB connection and so may reduce the power available for the device at the "B" end.