Why do LED lights still have a little glow after being switched off?
Por Amy Topsun lightingFebruary 10th, 2025vistas 36
In daily life, sometimes we encounter situations where the LED light still emits a faint light after turning off the switch. The five common reasons may include the following:
5 common reasons
1. The switch controls the neutral line (wrong wiring)
Problem: If the switch is installed on the neutral line instead of the live line, the light is still connected to the live line after it is turned off, forming a weak loop current.
Judgment: Use a tester to detect the light outlet after switching it off. If the neutral line end is energized, it is a wiring error.
2. The switch has an indicator light or night light
Problem: The LED indicator light or night light module built into the switch will form a tiny current loop, causing the LED light to produce a faint glow.
Typical phenomenon: Common in double-control switches or smart switches with indicator lights.
3. Line induction or leakage
Problem: The induction electricity generated by long-distance parallel wires or leakage caused by aging line insulation forms a weak current.
4. LED driver design defects
Problem: The driver filtering of some low-priced LED lights is imperfect and sensitive to tiny currents, resulting in the afterglow phenomenon.
5. Smart device interference
Problem: Smart switches, dimmers, or IoT devices require a standby power supply and may maintain a small current.
How to solve it?
1. Correct the circuit wiring
Make sure the switch controls the live wire instead of the neutral wire. An electrician needs to adjust the circuit (key item to check).
2. Change the switch type
You can use a standard switch without an indicator light or choose a model with an indicator light connected parallel to the front end of the switch (professional installation is required).
3. Add a bleeder resistor
To release the induced current, connect a 500kΩ~1MΩ/1W resistor in parallel at both ends of the LED lamp (pay attention to the risk of resistor heating).
4. Use a resistor-capacitor absorber
Add an RC circuit (such as a 0.1μF capacitor in series with a 100Ω resistor) to absorb high-frequency interference current.
5. Replace high-quality LED lamps
Choose a brand of LED lamp with a driver circuit and a bleeder circuit that is not sensitive to weak currents.
6. Check the insulation of the line
If there is leakage in the old house line, the wires must be repaired or replaced.
Precautions
1. Safety first: Professional electricians must power off and handle live operations to avoid the risk of electric shock.
2. Smart device adaptation: If using a smart switch, confirm that it is compatible with LED lights and turn off the "night dim light" function.
3. Simplify the circuit: First, remove unnecessary dimmers or complex control modules and test the basic circuit.
By checking the above reasons and solving them in a targeted manner, the glow light phenomenon after the LED light is turned off can be effectively eliminated. If it is difficult to solve it by yourself, it is recommended that you contact a certified electrician for system testing.
