Surface-Mount Overhead Door Alarm Sensor

Designed specifically for overhead garage doors with wide gaps, this surface-mount magnetic switch alarm sensor combines mechanical resilience with environmental resilience. Its metal body and protective metal tube are fully epoxy sealed to resist moisture ingress, dust, and temperature fluctuations. Dimensions are approximately 60mm × 20mm × 15mm (±1–3cm), with a lightweight yet solid 85g build. The included adjustable L bracket enables rapid, tool-assisted alignment on vertical or horizontal door tracks — accommodating variations in rail thickness and mounting surface angle. Electrically, it operates as a normally closed (NC) contact: conducting when the door is shut (magnet within ≥50mm), and interrupting the circuit upon opening to alert connected security systems. Compatible with standard 28V DC alarm circuits (max 0.2A / 3W), it integrates seamlessly with existing UK home security infrastructure without additional components.