Sensors

Understanding How Sensors Work

The principle behind sensors for lighting control is the detection of specific environmental factors, such as motion or the amount of light. Depending on the application and the desired accuracy, different types of sensors are available.

How Motion Sensors Function

Motion sensors detect movement within a defined detection area and then activate a connected device, such as lighting. Various detection technologies exist:

• PIR sensors (Passive Infrared): These are the most commonly used motion sensors. A PIR sensor responds to changes in infrared radiation (heat) within its detection field, such as the body heat of people or animals. When a temperature difference is detected between an object and its surroundings, an electrical signal is activated. These sensors do not work through walls or glass. Find more information about PIR sensors in our article.
• HF sensors (High-Frequency): These active sensors emit electromagnetic waves in the high-frequency range. These waves are reflected by objects and living beings. Through the Doppler effect, motion is detected by a change in the frequency of the reflected waves. HF sensors are independent of temperature and can even detect through thin materials such as glass, wood, or plasterboard, allowing for concealed installation.
• Ultrasonic sensors: These sensors emit high-frequency sound waves and measure their reflection. Like HF sensors, they react to any movement regardless of temperature and can detect through certain materials.

Motion sensors can be configured for range (how far the sensor detects), the duration the light stays on after activation, and light sensitivity (at what level of twilight the sensor becomes active).

How Dusk-to-Dawn Switches Function

A dusk-to-dawn switch, also known as a day-night sensor or light sensor, measures the amount of ambient light (lux). As soon as the light intensity drops below a preset level, the connected lighting is automatically switched on. When it gets light again, the lighting automatically switches off. This type of sensor is often used for street lighting, garden lighting, or advertising lighting.

The sensitivity of a dusk-to-dawn switch is often adjustable, allowing you to determine at what light level (expressed in lux) the lamp switches on or off. Many dusk-to-dawn switches also have an adjustable delay, so that brief changes in light (for example, from lightning or car headlights) do not immediately lead to unnecessary switching of the lighting.

Practical Applications for Sensors

Integrating motion sensors and dusk-to-dawn switches offers various benefits in different environments. These smart additions contribute to both comfort and functionality.

Lighting Control for Convenience and Energy Savings

• Outdoor lighting: Sensors are widely used for outdoor lighting, such as at entrances, driveways, or backyards. A motion sensor switches the light on upon arrival or when detecting unwanted visitors, providing security and a welcoming appearance. A dusk-to-dawn switch ensures your garden lighting automatically turns on at dusk and off at sunrise, contributing to a pleasant atmosphere without unnecessary energy consumption.
• Hallways and storage rooms: Indoors, motion sensors are suitable for spaces where light is not needed continuously, such as hallways, stairwells, basements, or storage rooms. The light turns on automatically when someone enters the room and off again when there is no more movement, which saves energy and prevents the light from being left on unnecessarily.
• Public spaces: In public buildings such as schools, offices, or warehouses, sensors ensure that lighting is only on when people are present, leading to significant energy savings.

Sensors for Increased Safety

In addition to controlling lighting, sensors also contribute to the safety of a property.

• Burglary prevention: Outdoor lighting that automatically turns on when motion is detected can deter potential intruders. Some sensors can also be linked to alarm systems.
• Orientation and preventing trips: Lighting of paths and stairs by motion sensors reduces the risk of falling in the dark.

Considerations for Choosing and Installing Sensors

For a functional and durable installation of sensors, there are several technical aspects to consider.

Selecting the Right Sensor

• IP rating: For outdoor applications, the IP rating (Ingress Protection) is very important. It indicates the degree of protection against dust and water.
  • IP44: Splash-proof, suitable for sheltered outdoor locations.
  • IP54/IP55: Protected against dust and splashing water, suitable for most outdoor conditions.
  • IP65: Jet-proof and completely dust-tight, suitable for exposed locations and direct contact with water jets.

  [Reference object: Link to our IP rating explanation page for a comprehensive table] View our detailed explanation of IP ratings for more details.

• Detection range and angle: These specifications determine the size of the area the sensor can monitor. Pay attention to the mounting height and the presence of obstacles that could affect the detection range. Sensors with a wider detection angle (e.g., 180° or 360°) are suitable for broader areas.
• Light sensitivity (lux): Adjustable on dusk-to-dawn switches and some motion sensors. This determines at what ambient light level the sensor becomes active.
• Maximum load: Always check the maximum switching capacity (in Watts) of the sensor to ensure it can handle the connected lighting.
• Power supply: Sensors are available for mains power (230V) or with batteries for wireless installations. The choice depends on the location and the availability of power outlets.

Practical Installation Questions and Solutions

Thorough preparation is important for a successful sensor installation. Below, common questions and their corresponding solutions are discussed.

How do I correctly connect a motion sensor to my outdoor light?

Connecting a motion sensor requires careful steps and a good understanding of electrical wiring. The most common connection involves three wires: live wire (brown), switched live wire (black), and neutral wire (blue), supplemented by an earth wire (yellow/green) for safety.

1. Switch off the power supply to the relevant circuit completely at the fuse box to work safely. Use a voltage tester to verify that the power is indeed off.
2. Determine the desired mounting location for the sensor. Consider the detection range and avoid obstacles that could hinder its operation.
3. Connect the brown live wire to the L terminal of the sensor. The black switched live wire, which runs to the lamp, is connected to the L1 terminal of the sensor. Connect the blue neutral wire to the N terminal of the sensor and the yellow/green earth wire to the earth symbol.
4. Mount the sensor securely to the wall. For outdoor sensors, ensure the wiring is waterproofed, for example, with casting resin joints or suitable cable glands on a junction box.
5. After installation and checking all connections, the power can be switched back on. Test the sensor and set the desired parameters, such as light sensitivity and on-time duration.

What is the difference between a motion detector and a presence detector?

Although the technology is similar, motion detectors and presence detectors differ in sensitivity and application area.

• Motion detector: Responds to larger, distinct movements. Once motion stops, the timer resets and the light switches off after the set time. These are suitable for areas like hallways, driveways, or outdoor spaces where brief presence is sufficient.
• Presence detector: These sensors are significantly more sensitive and detect even the smallest movements, such as typing on a keyboard or turning a page. They are designed to monitor continuous presence and keep the light on as long as any movement is detected, even if it is minimal. Presence detectors are particularly suitable for offices, meeting rooms, or restrooms where people are present for longer periods with subtle movements.

Where should I place the sensor to prevent false alarms?

Correct placement is important to prevent unwanted activation (false alarms) and ensure reliable operation.

• Avoid direct sunlight: Do not place sensors in direct sunlight, as sudden temperature changes in the sensor itself (for PIR) or rapid changes in brightness (for dusk-to-dawn switches) can lead to unnecessary activation.
• Keep distance from heat sources: For PIR sensors, they should not be placed too close to heat sources such as ventilation grilles, air conditioners, or heating elements, as the temperature differences can trigger the sensor.
• Avoid obstacles: Ensure the detection area is free from obstacles like trees, shrubs, flags, or cars that could unintentionally activate or block the sensor.
• Optimal mounting height: Consult the sensor's specifications for the recommended mounting height. This affects the effectiveness of the detection range and sensitivity. For outdoor sensors, a height of 2 to 3 meters is often recommended.

By taking these practical considerations into account during selection and installation, you will create an effective and trouble-free system for automated lighting control with sensors.