LED lamp flashes - what is the cause?

If the LED light only flashes or glows after switching off, the question often arises as to what is the cause. In this article you can read about possible reasons for after-flashing or afterglowing, and what can be done to eliminate them.

Cause of flashing and afterglow

LED lights often start at very low currents. This phenomenon is also known from energy-saving lamps. As soon as a low voltage develops on the lamps, they briefly start to flash or glow slightly, even if they are actually switched off.

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Even the smallest currents and even applied electromagnetic fields can be enough to make an LED light glow.

Such currents can arise from different causes:

  • from a changeover circuit
  • of illuminated switches (glow switch)
  • of leakage currents
  • of dimmers
  • from nearby electromagnetic fields

Changeover circuits

With changeover circuits, these problems occur frequently, even if they are carried out correctly. The reason for this is the recurring currents that cause the LED to glow, even with correct execution.

If a so-called "Hamburg circuit" has been built, you can assume that in this case always Currents will flow. Such circuits should not be used when LEDs are light sources.

Glow switch

Illuminated switches also generate very low currents and should be replaced if possible.

Leakage currents

Leakage currents can occur quite frequently, especially in older installations. This is often unavoidable. Renewing the installation in critical areas often helps here.


Not all LEDs are dimmable, only suitable dimmers may be used. Here, too, there may be a reason for LEDs to glow afterwards. Only the light bulb could always be dimmed without any problems.

electromagnetic fields

Even nearby electromagnetic interference fields (such as a cable close to the luminaire) can cause minimal voltages in the lamp.


Basically, the solution is to connect a sufficiently large resistor in front of the lamp, which prevents corresponding currents when switched off. However, the principle must always be adapted to the individual case.

Tips & Tricks You are not alone with your problem. These problems recur in many households. There is currently no professional solution for retrofitting. However, your electrician can analyze the problem and fix the cause of the problem by installing an appropriate device.