Patent landscapes › Home & cleaning

Is a extension cord patented?

Short answer: specific designs of a extension cord have been patented many times, but "a extension cord" as a general idea is not what is protected. What matters is the exact combination of features in your version.

What our index shows
  • 355 US and WO patent publications since 2000 have a title matching “extension cord” or a close variant (our index of 9.7 million patent families; one publication per family).
  • Among the 174 best keyword matches we examined, 36 were published in 2020 or later, and the earliest was published in 2000.
  • Most frequent assignees in those matches: LAI LI-CHUN (5), POWERTECH IND CO LTD (3), O'ROURKE KEVIN (3), NUNES VINICIUS JOSE GOMES (2).
  • Most common patent classes (CPC subclasses): H01R (124), H02G (27), B65H (19), H02J (15).

Counts come from keyword matching on titles and abstracts, so they are indicative, not a legal count. Some matches are different products that share a word.

14 real patent publications related to a extension cord

  1. Extension cord plug enclosure US-2025279609-A1 2025 · PROTECT A PLUG D/B/A
    An enclosure for an extension cord connector having a first container member forming a first receptacle and a second container member forming a second receptacle. The adjoining edges of the first and second receptacle form a conti…
    View on Google Patents
  2. Apparatus for Powering a Laptop Computer Without an Extension Cord Using Rechargeable Batteries Compatible with Conventional Power Outlets US-2020285289-A1 2020 · BUCKLEY ISAAC AARON
    An apparatus for powering a laptop computer without using a power cord. The laptop is sold with two interchangeable batteries, which can charge by being plugged directly into a wall outlet, along with an internal battery to power …
    View on Google Patents
  3. Electrical extension cord with a unitary and convertible two or three prong plug end US-9660382-B2 2017 · Beaty Cleodis
    What is presented is an extension cord with a convertible electrical plug end that can be connected to grounded and ungrounded power supply outlets. The extension cord comprises an extension cord and a plug end and is configured t…
    View on Google Patents
  4. Surge Protected Extension Cord with Multiple Outlet Sections US-2016329673-A1 2016 · MCCORMICK JAMES DOYLE
    An adjustable length power strip that is designed to protect connected electrical devices from power surges. The apparatus is configured to resemble traditional power strips and extension cords. The apparatus includes a primary po…
    View on Google Patents
  5. Full- auto retractable, built in extension cord and multi-outlet adaptor jack WO-2016036328-A1 2016 · CANAYAKIN RECEP DORUK
    The invention relates to a full-auto retractable, built in (in-wall) extension cord and multi-outlet adaptor jack that is an electrical unit powered by any in-wall power line ranging from 110V to 250V. The unit is designed to be i…
    View on Google Patents
  6. Portable Device for Supplying Outlets Including Retractable Electrical Extension Cord US-2011197794-A1 2011 · NUNES VINICIUS JOSE GOMES
    “PORTABLE DEVICE FOR SUPPLYING OUTLETS INCLUDING RETRACTABLE ELECTRICAL EXTENSION CORD” consists in a body ( 1 ), on a pillar shape, with a wide base ( 2 ) in order to confer stability to the device. On the top of the body, there …
    View on Google Patents
  7. Extension cord capable of providing estimated power costs incurred by an electrical appliance plugged thereinto US-7511633-B2 2009 · CHANG CHIA-MING
    A method for providing estimated power costs incurred by an electrical appliance, which is plugged into a receptacle of an extension cord, includes enabling operation of the extension cord so as to measure electric current flowing…
    View on Google Patents
  8. Charge apparatus of an extension cord plug US-7426126-B1 2008 · LAI LI-CHUN
    A charge apparatus of an extension cord plug is provided. The charge apparatus is set inside an outlet and connected to an USB interface outside the outlet. When the outlet is electrified, the plug thereon is able to provide power…
    View on Google Patents
  9. Extension cord retention and plug retention system US-7168973-B2 2007 · CREDO TECH CORP
    A retaining system including a power cord retaining system and a cord plug retaining system for use with a power tool. The power cord retaining system is configured for accommodating an extension cord and includes a cord capture f…
    View on Google Patents
  10. Biasing and adjustable extension cord-retaining device for preventing disengagement of male-to-female adaptor plugs US-6846196-B1 2005
    A retaining device for use with interconnecting plug ends of first and second extending cords. A main gripping body exhibits a first pair of arcuately extending and spaced apart gripping portions. A secondary gripping body is slid…
    View on Google Patents
  11. Retractable extension cord housing having a low-profile plug holder US-6848937-B1 2005
    A retractable extension cord housing with a low-profile plug holder retractably houses an extension cord in a hollow body and has an external surface. The plug holder comprises a plug recess, a cord groove and an optional retainin…
    View on Google Patents
  12. Wiring outlet with retractable extension cord mechanism US-6648677-B1 2003
    A wiring outlet assembly having a fixed wiring outlet and a moveable wiring outlet socket member adapted to seat within a cavity of the assembly and removably positionable from the cavity; the removable outlet socket member being …
    View on Google Patents
  13. Electrical extension cord with convertible plug and accommodating receptacle US-6464519-B1 2002
    An electrical extension cord includes a male plug convertible between standard residential or blade-type plug elements and twist-lock blade elements, and a female receptacle plug designed to accommodate both standard and twist-loc…
    View on Google Patents
  14. Extension cord plug cover US-6250946-B1 2001
    An extension cord plug cover that is sealable over a connected extension cord plug and socket to provide a watertight seal therearound. The plug cover includes a hard plastic clamshell cover filled with a resilient closed cell foa…
    View on Google Patents

What this means for your idea

Because patents cover specific combinations of features, the useful question is not “has a extension cord been patented?” but “has my combination of features been described before?” Household products tend to differ in the mechanism (how something attaches, folds, dispenses or cleans) rather than the basic idea.

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Guides that help with this

First-look landscape. Not exhaustive. Not legal advice. This page lists keyword-matched publications from a limited database; it does not say whether any product is or isn't covered by a patent, whether a patent is still in force, or whether your idea is patentable. Consult a registered patent attorney or agent.