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Knife switch

technology Maturity 11-13 Next article →

A knife switch controls the flow of electricity.

Open knife switch
Open knife switch

It has a metal lever called a knife. This lever is on a hinge. The hinge is on a base. The base is insulated. This means it does not let power flow through it. The knife has an insulated handle. You lift the knife to stop the power. You push it into a slot to start the power.

Electrical Machinery 1917 - knife switch
Electrical Machinery 1917 - knife switch

Some switches have one slot. We call these single-throw switches. Other switches have two slots. These are double-throw switches. The knife can go into either slot. You can also use one handle for many knives. This is a multi-pole switch.

DPDT knife switch in closed position
DPDT knife switch in closed position

These switches are rare now. They are mostly used for science shows. People like to see how they work. But they can be risky. The metal parts are out in the open. This can cause a shock. They can also make sparks called arcing. This can cause fires. New switches keep metal parts inside safe boxes.

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🖼️ Images & Media (4)
File:Open knife switch.jpg
Open knife switch.jpg
File:IEEE 315 Contacts, Switches, Contactors, and Relays Symbols (52).svg
IEEE 315 Contacts, Switches, Contactors,...
File:Electrical Machinery 1917 - knife switch.jpg
Electrical Machinery 1917 - knife switch.jpg
File:DPDT knife switch in closed position.jpg
DPDT knife switch in closed position.jpg
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