After comprehensive analysis of the closed switch, LED lights will still weak light of reason and solution

After a comprehensive analysis of the reasons and solutions for the weak light of the LED lights after turning off the switch. LED is a solid-state semiconductor device that can convert electrical energy into visible light, that is, light-emitting diodes, which can directly convert electricity into light. Many owners will find after the decoration is completed and settled, sometimes the lamps and lanterns will turn off the switch at night and still emit dim light. Is this a decoration problem or a lighting problem? Should you pay for decoration? Renovation is a troublesome thing, and there are dim lamps after the decoration, I believe it is difficult for everyone to have a good mood. So today we will analyze the reasons for which lights have dim light after decoration:

First, let’s start with the principle of LED: the core of the LED is a semiconductor light-emitting diode chip. One end of the chip is attached to a bracket, one end is the negative pole, and the other end is connected to the positive pole of the power supply, so that the entire chip is encapsulated by epoxy resin. A single LED lamp bead can only work under low voltage (about 3V) and low current (about a few milliamperes), and the light emitted is very weak. Many LED lamp beads need to be connected in series or in parallel; at the same time, a single LED lamp bead is unidirectional (single-phase conductivity of the diode). In order to make full use of the positive and negative half-cycle current of the alternating current, an integrated circuit chip is required. The AC 220V power supply is transformed into voltage and current DC to meet the power supply requirements of the LED lamp bead assembly, so that it can emit light normally.

LED lights require small currents and are very sensitive to voltage and current. In use, they will cause induced light emission due to various complex reasons. So what is the reason why the LED light still emits weak light when the switch is turned off, and what is the solution?

1. The neutral line is live

This is the most common situation, ①because the hot wire directly enters the base of the lamp when the plumber is arranging the wires, and the neutral wire enters the control switch. As a result, even though the switch is disconnected, the live wire still has current flowing through the light to reach the switch, causing the light to remain slightly bright. Solution: In this case, adjust the wiring and let the switch control the live wire.

The switch controls the neutral wire, causing current to flow through the lamp

②Because the plumber connected the wrong line when the main gate was connected, and the fire-neutral line was connected reversely, this accidentally reversed all the fire-neutral lines, causing all switches to control the neutral line. The solution to this situation: just reverse the incoming line.

The switch correctly controls the live wire

③If the switch is controlling the live wire, and the traditional mechanical wall switch is used, and it still emits light, the neutral wire is charged. It is a very common phenomenon that the neutral line is charged. If the neutral line is not well grounded, the three-phase load of the transformer is unbalanced, the line is too long, the wire diameter is too small, or the neutral line current is too large, the neutral line will be charged.

Solution: Re-ground the neutral line or carry out low-voltage transformation (this requires the property to be easily solved by the power supply company).

2. Wiring error occurs in the dual control switch

Wrong connection, although it can also be used

There are several wiring methods for dual control switches. If the wrong connection method is used, the traditional incandescent lamp will not turn on, but for the LED lamp, because it is actually a direct current, it will turn on slightly after turning off the light. Solution for this situation: Install the normal control live wire connection and re-wire.


Correct connection, any switch can cut off the power

The wiring method of the double control switch: single connection double control switch, there are three contacts at the back, namely L, L1, L2. Connect the two L1 and L2 respectively, the live wire is connected to the L contact point of a dual-control switch, and the neutral wire is connected to the L contact of the other dual-control switch.

3. The switch has an indicator light, and uses electronic and touch switches

There is an indicator light inside the switch, a slight current will flow after the light is turned off

Electronic touch switch

If the lamp uses electronic touch switches, such as infrared, voice control, and remote control switches. There may also be dim light after turning off the light. Solution for this situation: ① Change the switch. ② Connect a 500K resistor in parallel at the inlet of the lamp. However, this method is measured by professional technicians, and non-professionals are better not to operate casually. And this method is invalid for the neutral line charging or the dim light caused by the patch leakage.

LED strip

4. Non-isolated driver, light source patch and substrate leakage

Many lamps are driven by inferior resistor-capacitor step-down voltage due to cost considerations, or the quality of the light source patch is poor, and there is patch and substrate leakage. The substrate copper coating and substrate capacitance effects can also cause light leakage. This is why in a room, some lights are bright and some are not bright.