Reed Switches NZ: Door, Window & Roller Door Sensors | ESS NZ

The Role of Reed Switches in Modern Security and Access Control

Reed switches are one of the most reliable and widely used components in security systems across New Zealand. Whether you are protecting a residential window, a commercial roller door, or a high-security access-controlled entry, a correctly specified reed switch provides the foundation for accurate door and window position detection. This guide covers the full range of reed switches available at Essential Security Supplies, helping installers and security professionals select the right model for every application.

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What Is a Reed Switch and How Does It Work?

A reed switch is a magnetically operated electrical switch. It consists of two ferromagnetic contacts sealed inside a glass or polymer housing. When a magnet (typically mounted on the moving part of a door or window) comes within the sensing gap of the switch body (mounted on the fixed frame), the contacts close or open the circuit. This change in state is detected by an alarm panel, access control system, or building management system.

Reed switches are available in two primary output configurations:

• NC (Normally Closed): The circuit is closed when the magnet is present (door closed). An alarm triggers when the circuit opens (door opens). This is the most common configuration for security applications.
• NC/NO (Normally Closed / Normally Open): Dual-output switches that provide flexibility for integration with different panel types.

Installation method and sensing gap are the two most critical selection criteria, covered in detail below.

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Surface Mount vs Flush Mount Reed Switches

The two primary installation methods are surface mount and flush mount (also called concealed or recessed mount). Selecting the correct type depends on the door or window frame material, aesthetics requirements, and the level of tamper resistance needed.

Surface Mount Reed Switches

Surface mount switches are fixed directly to the face of the door frame and door leaf using screws or adhesive. They are quick to install, easy to service, and suitable for most residential and commercial applications. The switch body and magnet are both visible once installed.

Flush Mount Reed Switches

Flush mount (concealed) switches are recessed into drilled holes in the door frame and door edge. They are invisible once installed, making them ideal for high-end residential installations, timber doors, and applications where aesthetics are a priority. They also offer a degree of tamper resistance as the switch is not accessible from the surface.

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Reed Switch Range at Essential Security Supplies

Our reed switch range covers residential windows, commercial doors, garage doors, roller doors, and high-security applications. Below is an overview of each model.

HC-31 Surface Mount Reed Switch (NC)

The HC-31 is a compact surface mount reed switch suitable for doors and windows with a sensing gap of 15-20mm. Its ABS housing, white finish, and copper terminal connections make it a reliable choice for standard residential and light commercial installations.

HC-38C Surface Mount Reed Switch (NC)

The HC-38C is designed for doors and windows with a 15-20mm sensing gap. With an ABS case, white finish, and 250mm lead wire, it is a straightforward surface mount option for alarm and access control integration.

HC-39 Surface Mount Reed Switch (NC)

The HC-39 is optimised for residential windows with a slightly wider sensing gap of 15-25mm. Its slim 23x13x6mm profile keeps it unobtrusive on window frames while maintaining reliable detection.

HC-41 Flush Mount Reed Switch (NC)

The HC-41 is a concealed flush mount reed switch for doors and windows. With a 10x20mm cylindrical profile and 15-20mm sensing gap, it is designed for recessed installation in timber or aluminium frames where a clean, invisible finish is required.

HC-56 Surface Mount Reed Switch (NC)

The HC-56 is built for garage doors, featuring a zinc alloy housing and a wider 30-40mm sensing gap to accommodate the larger clearances typical of garage door frames. Its grey finish and robust construction suit both residential and light commercial garage applications.

HC-55ZL Surface Mount Reed Switch (NC)

The HC-55ZL handles the largest sensing gaps in the range at 50-70mm, making it the correct choice for roller doors and garage doors with significant frame clearance. The zinc alloy body measures 106x38x10mm and includes a 550mm lead with a 380mm stainless steel protective tube for durability in exposed environments.

BP-30 Surface Mount Reed Switch

The BP-30 is a surface mount reed switch suitable for standard door and window applications.

BP-50 Flush Mount Reed Switch (White)

The BP-50 is a UL-listed and CE/RoHS-compliant flush mount reed switch with a 9x19mm contact and magnet size, a standard 15mm sensing gap, and 305mm 22 AWG leads. Its compliance credentials make it suitable for installations requiring certified components.

MS-424M Reed Switch Roller Door

The MS-424M is a heavy-duty roller door reed switch with a zinc alloy and silver contact construction. It supports both NC and NO output configurations and accommodates a 50-60mm sensing gap, making it one of the most capable roller door sensors in the range. The surface mount housing measures 105.7x50x50mm.

SMSS-1 Securitron High Security Reed Switch

The SMSS-1 is Securitron's premium tamper-resistant reed switch for high-security door position detection. It operates on 10-30VDC (12/24V DC compatible) and is available in three versions: MSS-1 with jacketed cable for hollow frame doors, MSS-1G with a 936mm stainless steel cable for other openings, and MSS-1C as a concealed unit for standard ANSI 4-7/8" strike cutouts. The anti-tamper output and false alarm reduction features make it the correct choice for access control and alarm systems in higher-security environments.

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Product Specifications

View our product range for full model-specific data and availability.

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Selecting the Right Reed Switch: A Quick Reference Guide

Use the following criteria to narrow down the correct model for your installation:

• Sensing gap: Measure the gap between the door/window and its frame when closed. Match this to the sensing distance specification of the switch.
• Installation method: Surface mount for speed and serviceability; flush mount for aesthetics and tamper resistance.
• Frame material: ABS-housed switches suit interior residential applications; zinc alloy models are better suited to garage doors, roller doors, and exposed environments.
• Output type: NC is standard for most alarm and access control panels. Confirm your panel's input requirements before specifying NC/NO models.
• Security level: For high-security or tamper-evident requirements, specify the Securitron SMSS-1 with its anti-tamper output and armored cable options.
• Compliance requirements: Where UL listing or CE/RoHS certification is required, specify the BP-50.

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Reed Switch Applications in New Zealand Security Installations

Reed switches are used across a wide range of security and access control applications in New Zealand, including:

• Residential alarm systems for doors and windows
• Commercial access control for monitoring door open/closed status
• Garage door and roller door position detection
• Gate and barrier monitoring
• Machinery safety barrier status detection
• Building management system integration

For guidance on reed switch selection for specific applications, refer to the New Zealand Security Association (NZSA) installation standards and best practice guidelines.

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Why Choose Essential Security Supplies for Reed Switches in NZ

Essential Security Supplies stocks a comprehensive range of reed switches from trusted brands including AAP, ESSL, and Securitron, covering every application from basic residential window sensors to high-security tamper-resistant door position detectors. All products are available for trade supply across New Zealand.

View our product range and order online today.