LEDs can glow or flicker after being turned off due to residual electrical charge remaining in the circuit or due to electromagnetic interference (EMI) from nearby electrical sources. When an LED light is turned off, especially if it is controlled by a dimmer switch or electronic control device, there may still be a small amount of electric current flowing through the circuit. This residual current can be enough to cause LEDs to emit a faint glow or flicker intermittently, even though they are supposed to be off.
The phenomenon where LEDs continue to emit light after being turned off is often attributed to leakage currents in the control circuitry or the LED driver. LED drivers typically contain components like capacitors that can hold electrical charge temporarily after power is removed. This stored charge can cause LEDs to remain dimly lit or flicker sporadically until the charge dissipates completely.
LED ghosting specifically refers to the situation where LEDs continue to glow or flicker after being turned off, resembling a ghostly effect. This effect is more pronounced in LED fixtures controlled by dimmers or electronic switches, where residual currents or EMI can interact with the LED’s semiconductor characteristics, causing them to illuminate slightly or flicker.
In some cases, LEDs may stay on or flicker when the power goes out due to the presence of backfeed voltage or voltage fluctuations in the electrical system. Backfeed voltage can occur if there is a fault or a nearby power source that continues to supply voltage to the circuit even when the main power supply is disconnected. This backfeed can be sufficient to power LEDs at a reduced brightness or cause them to flicker as the voltage fluctuates.
To mitigate these issues, it’s essential to ensure that LED fixtures are compatible with the dimmer switches or control systems being used. Using dimmers specifically designed for LED lighting can help minimize residual currents and prevent ghosting or flickering after the LEDs are turned off. Additionally, addressing grounding and wiring issues in the electrical system can reduce the likelihood of residual currents or backfeed voltage affecting LED operation, ensuring reliable performance and minimizing unwanted illumination when LEDs are supposed to be off.
