Mine signal switch features single pole normally open double break switch contacts. Switch is actuated by a spring-loaded plunger which returns to the normal position when the operating force is removed. Standard pull spring on switch unit is 10 lbs. Visible signal observable from the front and both sides through portholes. Buzzer provides audible signal. It is used for visible, audible and remote control of signalling circuits. In non-hazardous areas of mines or process industry facilities where a rugged enclosure is needed for protection from falling ore and other material or dripping water.