FiberStrike® fiber optic interlock switches are the most advanced solution for monitoring the status of virtually any access portal (manholes, hand holes, doorways, vaults and power grids) today. Benefiting from the nearly limitless working distances allowed by fiber optics, these interlock switches can be networked over a wide perimeter while taking advantage of existing standard communication fiber networks. Detecting and locating any attempts to cut, break, open, tamper, or intrude any secure area. Additional advantages include the passive nature of each sensor with no need for power at any sensor location, immunity to environmental problems that plague electrically-based sensors, and the ability to network virtually any number of sensors over non-conductive optical fiber into a single monitoring system that can be tens of kilometers removed from the sensing area. While FiberStrike® switches have been created for intrusion detection at access portals such as hatchways, manholes and hand-holes, these sensors also are ideal for high EMI/RFI industrial environments requiring many open-close measurement points, or any other locations where knowledge of many go/no-go contact states in a network is required. A multitude of different switch actuator heads (arms, rollers, feeler rods, etc.) is available to meet particular applications.