Motion detector subsequently connected to a lamp

Often comes the idea, the comfort of a motion detector only when the electrical installation is already completed. This means home improvement often faces the problem of subsequently connecting a motion detector.

Note before retrofitting

Motion detectors offer a lot of comfort in different situations. But most motion detectors are not planned in the house, so they must be retrofitted. However, before you buy a motion detector, you must clearly define what requirements this device must meet:

  • free monitoring field (without obstacles)
  • must or can be behind obstacles
  • Size of the area to be monitored (range of the motion detector)
  • Consideration of the existing installation

Consideration of the existing installation

The existing installation is particularly important. A distinction is still made between incandescent bulbs, fluorescent tubes, energy-saving lamps and LED bulbs. In particular, LEDs require significantly less voltage. At the same time residual current can be present on the phase with motion detectors. LEDs can light up easily (permanently), fluorescent tubes can be ignited again and again. Therefore, a motion detector with a switched relay should be used in such lighting.

If you have LED lighting and want to install a switch in addition to the motion detector, it is essential to ensure that phase L is switched (according to the VDE, it is also permissible in Germany to pass the neutral conductor N through the switch).

A special situation exists when a motion detector is to be subsequently connected to, for example, a staircase lighting, which has a timer. Then a system or a motion detector with impulse function is needed.

Free surveillance area or obstacles

Both are possible. There are different types of motion detectors with which the respective requirement can be met. For example, PIR detectors (infrared) that require direct contact because they react to heat; or HF detectors, they themselves work behind walls.

The size of the area to be monitored

How big the area in which the motion detector should trigger is also crucial. In addition, it may be necessary that a motion detector is insufficient. Then two detectors can be connected to a lamp subsequently. The two motion detectors are then connected in series. It should be noted that the two switching times of the two detectors can add up.

Tips & Tricks

The connection of a motion detector is not very difficult. If you want to connect a motion detector, you will find the right guide.

Video Board: PASCO Motion Sensor