Connect a motion detector


Motion detectors offer a lot of comfort. With their help you can operate electrical circuits without physical contact. How to connect a motion detector and what to pay attention to during assembly has been summarized in the following guide.

Operation of conventional motion detectors

Motion detectors work on a simple principle. A sensor detects movements and triggers a circuit on it. There are three main types of motion detectors:

  • with infrared sensor (passive infrared motion detector PIR)
  • with high-frequency sensor (HF or radar motion detector)
  • with photocell

All mentioned motion detectors have different characteristics. You must consider this before installing the purchase. This means that only radar or HF detectors can be installed invisibly, ie practically concealed, and still react. Motion detectors with infrared sensors, on the other hand, are very sensitive to light, which can also be decisive. Incidentally, PIR detectors are the most commonly used motion detectors.

Install the cable according to your own ideas before installation

The incoming and outgoing lines can be laid according to your requirements, ie on-wall or flush-mounted. When laying, make sure that you dimension the lines generously in order to be able to carry out the installation without difficulty (too short cables). When cabling then some special features must be observed.

Instructions for connecting a motion detector

We will not provide any direct instructions on how to install a motion detector as you will need to prove your expertise in connecting a motion detector to the 223V mains. Otherwise there is danger to life and of course the risk of a short circuit or possibly resulting in a cable fire. The following illustration for installing a motion detector is therefore more of a practical illustration.

Example installation for the connection of a motion detector

Of course, you first have to know where you need or want to attach the motion detector. Accordingly, the cables must be sized for wiring. When wiring, we describe how to connect a motion detector between a light switch and a lamp.

Depending on the consumer used, pay attention to the connection of the supply line

The following note: Surprisingly, according to VDE, it is permitted to switch the non-current-carrying neutral conductor N, for example, to place it directly on a luminaire, while the current-carrying line L is connected directly to the consumer. This distinction is explicitly important when using LED bulbs.

Because compared to other bulbs, the life of LEDs is not reduced by switching on and off and operating time (on / off), but almost exclusively by the operating time. If L was directly connected (not switched on) to the LED light, residual current could flow, which is like normal operating time. When switching the outputs should definitely come out of the light switch as follows:

  • switched: L
  • not switched: N
  • and of course the protective conductor PE

The motion detector is now equipped with four lines:

Connection diagram or scheme on the motion detector

  • L1 or L: input current carrying line (phase), black or brown
  • N: not current leading neutral, blue
  • L2 or output L: current leading to the consumer outgoing (often marked with an arrow), brown for example
  • PE: protective conductor, green-yellow

Connection of protective conductor PE

Of course, the fuse must be unscrewed or turned off before wiring. Then the protective conductor PE coming from the switch is connected to PE at the motion detector. For this purpose, a multiple terminal is used because the protective conductor is pulled further to the consumer and connected.

Cabling from neutral N

The same procedure then applies to the neutral conductor N. Coming from the switch, N is connected to N at the motion detector by means of a multiple terminal. In this terminal N is then clamped for de consumers.

Clamping of phase L / L1 and output or L2

In the current-carrying phase L, the connection runs a little differently. The phase L coming from the light switch is connected to the phase L or L1 on the motion detector. There is no need to use a multiple terminal as L or L1 will not continue to the consumer. Instead, with an additional line (if L or L1, for example, black, then brown) L2 or "output" or wired outgoing arrow wire is wired.

Attach the motion detector before connecting

Before installing the electrical wiring, the installation of the motion detector is prepared, so the holes set. Depending on the model used, the various cables must be installed either in an external junction box or in a box integrated in the motion detector. In the latter case, of course, you can not fix the motion detector before the electrical installation.

Tips & Tricks

If you want to "illuminate" large areas with a motion detector, you may need two motion detectors. Of course, you can also connect two motion detectors to a light switch. For this purpose, the two motion detectors are simply connected in series. Follow our link and get a detailed description of the connection and connection diagram.


Video Board: How To Wire A Motion Detector To An Alarm Control Panel