The GWS detects penetration through walls, floors, ceilings, doors and other barriers by a "break wire" method. The grid wire is applied to the surface to be protected in a criss cross pattern such that a wire grid of approximately 4 inch squares, covers the entire surface. The wire grid is then covered with paneling or plywood for protection. Any penetration through this barrier in excess of a 4-inch square results in a break in one or more of the grid wires. The sensor does not produce an intrusion alarm by any means except a physical break in the electrical continuity of the circuit. A break in the electrical continuity of the circuit will result in an alarm being transmitted to, and recognized by, a control unit. The GWS is a component of the Joint-Services Interior Intrusion Detection System (J-SIIDS).