LED afterglow, what causes it and how can it be resolved.

Friday, 2 June 2023
A phenomenon that is becoming more prevalent and is a consequence of the increasing efficiency of COB LEDs is afterglow. The LEDs become so efficient that they require very little energy to glow after being turned off.

This is caused by leakage current, which is almost impossible to prevent. Many devices have capacitors or transformers, creating a - although small - leakage current. By switching not only the phase but also the neutral, the glowing effect in LED lamps due to leakage current can be counteracted, but you need to use a double-pole switch. The double-pole switch has the disadvantage that the neutral must also be present at the switch itself, whereas with a single-pole switch, only the phase is present. Often, an additional neutral wire needs to be laid from the switch to the light point. However, a double-pole switch does not always solve the problem.

In the case of long installation wires and full conduits, the phase and neutral wires may generate a small inductive voltage. This is not a defect, problem, or incorrect connection; it is a characteristic of electrical alternating current. Even when the phase and neutral are switched off, other current-carrying wires in the same conduit may generate inductive voltage. If this happens, the LED lamp may still light up, even if the double-pole switch is turned off.


Solutions:

  1. Swap the L&N.
  2. Install resistors, see diagram below.
  3. Connect the negative terminal to the ground on the secondary side of the LED driver.