How to properly install a motion sensor

How do they work, where to put and how to install them

Especially for those, who get afraid in the dark, motion sensors are a gift from heaven. A dark alley, garden or area will automatically light up and help you navigate on difficult surfaces, like wet or icy roads, whilst literally shed light on noises, which you cannot identify. But motion detectors do not only come handy for the easily scared. They also contribute a lot to everybody’s safety, when the light is switched on. Best is that motion sensors for lighting applications are not expensive and can be installed easily.

How do motion detectors work?

In order to use one on the outside, let’s first take a look, what is happening on the inside. When you ever have had a closer look at a motion sensor, you might have seen the eyes, which remind of the eyes of a fly. These eyes actually are ‘electronic eyes’, which detect heat waves, or also known as “infrared waves”. These waves radiate from moving objects and can be sensed by the sensor across its viewing field. In particular, warmer objects, such as living beings (humans, animals) or cars, are perfectly suited for turning on the light. In order to save energy by using daylight, a special photocell prevents the motion sensor from switching on the light. Motion can be detected from a top view of up to 240°, whilst the distance range is adjustable on most sensors, some of them extending 20 metres.

Adjusting the ranges is a very useful perk, as motion sensors, which are placed outdoors can react to trees in the wind, a passing by car or just your neighbour’s dog. In order to prevent the motion sensors not only getting on your nerves, but also on the whole neighbourhood’s nerves, just reduce the range and/or narrow down the field of view and only the desired area will make the light turn on.

Furthermore, outdoor motion sensors, which are especially created for outdoor use often come together with a switch, which allow to turn on the light manually. This comes especially handy, when you intend to have the light turned on all night, even without movement.

KNX boardroom with chairs in room with large windows

Where to put them?

The easy answer is: Put them, where you want the light to be turned on, when you get there. This would apply to front and back entries, driveways or areas in your garden. Benefits of placing the motion sensors at areas of property access is that not only your way will be illuminated, but it will also get unauthorised intruders to retreat, making the motion sensor the best low-cost security device.

The ideal position is at a height of 2 – 3 meters above the ground and where it would sense most movement in the pre-adjusted range across the sensitivity zone rather than directly toward the detector. Needless to say that the corner of a room is the worst place in order to make the most efficient use of a motion sensor.

electrician apprentice looking at wiring in home

How to install motion detector lights, step-by-step

Safety first! Therefore, in case you do not have any technical background, but do not want to miss the advantages and benefits of the first level smartness of your home, call a professional. A full list of all certified installers can be found here.

Motion sensors are fairly easy to install, but as it is with every individual person, each brand has its own individual characteristics. Therefore, in order to fully understand what you are dealing with, have a look at the manual first. Also before actually buy the model, which you have chosen, have a closer look at the box, in order to understand what is inside the box. And again, in case you are not sure, better ask someone, who can help you with the installation, such as a certified KNX Partner.

close up of wiring in knx integrated home

Once you have made your choice, get started with the installation:

  • Check your gear: What you need in normal cases are multi-screwdriver, voltage tester and Wire stripper/cutter
  • Switch off the electricity and make sure with the voltage tester if the electricity is really switched off
  • Install the wall-mounted fixture in your wall and wire the fixture. At this step, take into consideration the different wires from neutral, hot and ground as well as each individual step, which you can find in the manual of the sensor
  • Mount the fixture and aim the sensor. When aiming, consider what purpose your sensor should serve and how to use it in the most efficient way.
  • Lastly: Set the control, according to your sensor’s purpose



  • Although you might have switched off the electricity, never touch the overhead power line, neither with your body nor with your ladder.
  • Furthermore, aluminium wiring should only be done by a certified professional, who is trained in using these wires.
  • Once you proudly finished your work, be certain by having a professional check your installation.

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