A safety switch 2 used in conjunction with a cable as a machine guard, the switch being actuated to cut power to attendant machinery when a predetermined tension in the cable is varied by for example pulling the cable, or the cable becoming loose. The switch 2 comprising a sliding cam 14 which is connected to a connection point 12 for the cable via a spring loaded shaft 10 which shaft also supplies said predetermined tension and acts to move said sliding cam 14 in a first plane when the predetermined tension is varied. The sliding cam 14 then acts on a transverse cam 36 moving it in a plane transversely disposed to said first plane which in turn acts to cut said power 30, 52.