World Library  
Flag as Inappropriate
Email this Article

Knife switch

Article Id: WHEBN0011539646
Reproduction Date:

Title: Knife switch  
Author: World Heritage Encyclopedia
Language: English
Subject: Electronic component
Publisher: World Heritage Encyclopedia

Knife switch

A knife switch is a type of switch used to control the flow of electricity in a circuit. It is composed of a hinge which allows a metal lever, or knife, to be lifted from or inserted into a slot or jaw. The hinge and jaw are both fixed to an insulated base, and the knife has an insulated handle to grip at one end. Current flows through the switch when the knife is pushed into the jaw. Knife switches can take several forms, including single throw, in which the "knife" engages with only a single slot, and double throw, in which the knife hinge is placed between two slots and can engage with either one. Also, multiple knives may be attached to a single handle and can be used to activate more than one circuit simultaneously.

Current uses

Though used commonly in the past, knife switches are now rare, finding use largely in science experiments where the position of the switch may be plainly seen in demonstration. The knife switch is extremely simple in construction and use, but its exposed metal parts present a great risk of electric shock, and the switch is subject to arcing when opened at higher voltages, which poses a further risk of shock or burns to the operator and can cause fires or explosions under certain conditions.

Open knife switches were supplanted by safety switches with current carrying contacts inside a metal enclosure which can only be opened by switching off the power. In modern applications, automatic switches (such as contactors or relays), and manual switches such as circuit breakers are used. These devices use a snap action mechanism which opens the switch contacts rapidly, and feature an arc chute where the arc caused by opening the switch is quenched. These devices also prevent injury due to accidental contact, as all of the current carrying metal parts of the switch are hidden within or surrounded by insulating guards.


This article was sourced from Creative Commons Attribution-ShareAlike License; additional terms may apply. World Heritage Encyclopedia content is assembled from numerous content providers, Open Access Publishing, and in compliance with The Fair Access to Science and Technology Research Act (FASTR), Wikimedia Foundation, Inc., Public Library of Science, The Encyclopedia of Life, Open Book Publishers (OBP), PubMed, U.S. National Library of Medicine, National Center for Biotechnology Information, U.S. National Library of Medicine, National Institutes of Health (NIH), U.S. Department of Health & Human Services, and, which sources content from all federal, state, local, tribal, and territorial government publication portals (.gov, .mil, .edu). Funding for and content contributors is made possible from the U.S. Congress, E-Government Act of 2002.
Crowd sourced content that is contributed to World Heritage Encyclopedia is peer reviewed and edited by our editorial staff to ensure quality scholarly research articles.
By using this site, you agree to the Terms of Use and Privacy Policy. World Heritage Encyclopedia™ is a registered trademark of the World Public Library Association, a non-profit organization.

Copyright © World Library Foundation. All rights reserved. eBooks from World eBook Library are sponsored by the World Library Foundation,
a 501c(4) Member's Support Non-Profit Organization, and is NOT affiliated with any governmental agency or department.