Abstract: A magnetic switch assembly (100) for electrically coupling with an electrical circuit of an alarm system (16) and for detecting relative movement between a first, stationary member (102) and a second, moveable member (104) is disclosed. The switch assembly includes a switch means (106) adapted for mounting within the first stationary member and a corresponding electromagnet assembly (108) having an electromagnet (120). The switch means includes a housing (110), a pair of spaced switch elements (112,114) supported in the housing that are electrically coupled with an alarm device or system, a ferromagnetic body (116) such as a ball positioned within the housing and moveable between the switch elements, and a ferromagnetic core (118) positioned above or adjacent one of the switch elements for biasing the body to either its closed or opened position. The electromagnet (120) is coupled with a suitable source of electricity and is switchable between on and off states.