Contact Strip Switch No. 11 Mk I (Service)

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Description: The device consists of two arms, each 2 ft. 9 in. long, connected to-gether by 6 in. of double-lead, flexible wire, and having another double lead of flexible wire provided with plugs to fit into the battery supplied with the switch. Each arm con-tains two brass strips held apart by insulating spacers every six inches. The strips are enclosed in red rubber tubing, the  ends of which are closed with waterproof rubber plugs. Supplied with each set is a 9-volt dry-cell battery, fitted with two sockets to re-ceive the contact-strip plugs, and with two screw terminals, to which are attached the leads to the detonator of the main charge.

Functioning: The passage of a vehicle over either arm forces the brass strips into contact with each other, completing the electrical circuit. The battery sets off the elec-tric detonator,firing the explosive charge.

Use: This switch is employed in a specialized form of trap designed to destroy wheel-ed or track vehicles. It is laid across a road surface in the probable path of enemy ap-proach

Installing: Before connecting the battery to the charge, test the contact strips with an electric blasting cap to make certain that the brass strips are not in contact, that pressure produces the proper contact, and that contact is not maintained after the pressure ceases.

Disarming: Disconnect the detonator leads from the battery.

Remarks: Because of the red covering of the contact strips, each arm should be painted, sprinkled with earth, or covered with grass, etc., to conceal it. It must not, however, be buried.