Door contact sensor BLOW 4931# (reed switch) model HO-03D, wired magnetic door/window sensor

Wired magnetic door/window sensor BLOW 4931# (model HO-03D) is a reed-switch type contact sensor designed to detect the open or closed state of doors and windows. The detector consists of a compact magnet and a separate reed-switch housing connected by wiring, enabling reliable state monitoring when integrated into wired alarm and security systems. The device provides a straightforward normally closed or normally open contact output depending on installation and wiring, allowing it to act as a trigger for perimeter protection, entry monitoring or arming/disarming functions.

Advantages

The sensor features a compact form factor that fits most door and window frames and a simple reed-switch mechanism that offers low-power, long-term reliability. Its wired connection eliminates battery management and reduces false alarms caused by RF interference. The separate magnet and contact housing allow flexible positioning for flush or surface mounting, while the straightforward electrical behavior simplifies integration with a wide range of wired control panels and alarm inputs.

Suitable for

• Perimeter protection of residential and commercial premises
• Monitoring individual doors and windows for unauthorized opening
• Integration with wired alarm panels, access control systems, and automation controllers
• Use as a zone trigger for arming and disarming sequences

Key specifications

• Detector type: reed-switch magnetic contact
• Mounting: surface-mounted or inset mounting depending on installation
• Connection: wired contact leads for integration into alarm circuits
• Operating principle: magnet actuates reed switch to indicate open/closed state
• Housing: compact plastic enclosure suitable for door and window frames
• Environmental suitability: intended for indoor use in typical residential and commercial environments

How to use

Install the contact housing on the fixed frame and the magnet on the moving leaf so that the magnet aligns with the reed-switch when the door or window is closed. Route and secure the sensor wiring to the alarm panel or control input, following the panel manufacturer’s wiring conventions for normally closed or normally open circuits as required. Test the sensor by opening and closing the door or window and verifying the corresponding state change at the control panel. Ensure mounting surfaces are clean and flat to maintain consistent gap and reliable switching.

Usage recommendations

Place the sensor where the magnet and contact can maintain a consistent gap when closed; avoid areas exposed to moisture or direct weathering. For reliable performance, follow the alarm panel’s wiring and tamper-monitoring guidelines and perform periodic functional checks as part of routine security maintenance.