A tripwire is a passive triggering mechanism. Typically, a wire or cord is attached to a device for detecting or reacting to physical movement.

Military applications

Such tripwires may be attached to one or more mines⁠especially fragmentation or bounding mines⁠in order to increase the area where triggering may occur. Trip wires are frequently used in

booby trap A booby trap is a device or setup that is intended to kill, harm or surprise a human or an animal. It is triggered by the presence or actions of the victim and sometimes has some form of bait designed to lure the victim towards it. The trap may b ...

s⁠where either a tug on the wire, or the release of tension on it, will trigger the explosives. Soldiers sometimes detect the presence of tripwires by spraying the area with

Silly String Silly String (generically known as aerosol string) is a toy of flexible, sometimes brightly colored, plastic String (structure), string propelled as a stream of liquid from an aerosol can. The solvent in the string quickly evaporates in mid-air, ...

. It will settle to the ground in areas where there are no wires; where wires are present, the "strings" will rest on the taut wires without triggering the explosive, due to the product's light weight. Its use in detecting tripwires was first discovered in 1993 by Sergeant First Class David B. Chandler, Chief Instructor of the

United States Army The United States Army (USA) is the primary Land warfare, land service branch of the United States Department of Defense. It is designated as the Army of the United States in the United States Constitution.Article II, section 2, clause 1 of th ...

's Sapper Leader Course. That year it was introduced to students attending the course, and it was later used in combat for this purpose by U.S. troops in the

Iraq War The Iraq War (), also referred to as the Second Gulf War, was a prolonged conflict in Iraq lasting from 2003 to 2011. It began with 2003 invasion of Iraq, the invasion by a Multi-National Force – Iraq, United States-led coalition, which ...

. Another detection method is the use of green

line laser A line laser is a device that employs a laser and an optical lens to project the laser beam as a line rather than a point (e.g. laser pointer). This may be achieved by passing the beam through a cylindrical lens or a Powell lens. Depending on the ...

s to illuminate and thus expose trip and command wires. The bright laser beam reflects off the tripwire and can be seen by the user.

Industrial applications

A tripwire may be installed in the vicinity of industrial equipment, such as a conveyor belt to enable workers to stop the equipment quickly. These may also be called emergency stop pull-cords.

References

{{Reflist Anti-personnel weapons Warning systems Security