The LED light is still flashing after turning off the lights, what's going on?
LED lights have brought us too much convenience. It is no compliment to say that the reason why today's nightlife can be so colorful is that LED lights are indispensable. But LED lights also have their flaws, that is, the "glass heart" - LED lights are much more sensitive to current than incandescent and fluorescent lamps. Therefore, if something goes wrong, it will show you the way of flickering and shimmering after turning off the light. Flashing and shimmering belong to the same type of failure, and the causes and solutions are the same, so they can be regarded as equal. Of.
The cause of the LED light flickering after turning off the switch is uncertain, and you need to rule it out one by one. There are three possibilities that may cause the LED light to flicker after turning off the switch:
1. The switch controls the zero line;
2. The lamp produces a self-inductive current;
3. After the switch is turned off, it still conducts current.
Below I will discuss the characteristics and solutions of each cause.
switch control neutral
Switching to zero control is a big taboo in lighting circuit wiring, and it is also the most common mistake made by many non-professional electricians. In the imagination of ordinary people, as long as there is a neutral wire and a live wire, the lamp can be lit, just like this▼
figure 1
But have you ever wondered what would happen if you reverse the order of the neutral and live wires? such as this ▼
figure 2
The above two pictures fully reflect the difference between the neutral wire and the live wire - the live wire always has a high potential, while the potential on the neutral wire is always zero. Let's look at Figure 1 first, where the live wire goes into the switch first, and then into the light. If the switch is opened at this point, the live wire is cut - the potential across the lamp is zero. Look at Figure 2 again. In this figure, the live wire enters the lamp first, and the switch controls the neutral wire at this time. When the switch is opened, the neutral in the line is disconnected - it is true that a circuit without a neutral cannot produce current (to be precise, a continuous high current). But the lamp is still connected to the live wire, in other words, the lamp still has a high potential.
The high potential across the lamp creates a potential difference, which in turn produces a weak current. A small current flowing through the light will cause flicker - this small current actually affects the starter of the light, and incandescent lamps without a starter will not flicker.
Long-term so, not only has an impact on the life of the lamp. It also poses a threat to the safety of maintenance personnel when replacing lights. Therefore, if this happens, the line should be adjusted in time.
How to determine whether the switch is controlled by the live wire? Use an electric pen to measure the switch or lamp terminal. Under normal circumstances, after the switch is disconnected, the switch part of the wire can light the electric pen, but the lamp part cannot. If the opposite is true, then the switch controls the neutral.
Also, if all the lights in the room are flickering, it is possible that the neutral wire is reversed at the distribution box. At this time, the wiring in the distribution box should be adjusted - the neutral wire of the lighting circuit should be reversed.
Lights generate self-inductive current
If the wiring at the lamp is dense, it is possible to induce induced electricity—two wires placed in parallel, close together, will form a capacitance. Having a high potential on one of the wires (live) and not the other (neutral) causes the neutral to be charged. At this time, the electricity on the zero line is induced electricity.
If the induced electricity on the zero line is small at this time, it will accumulate on the internal capacitance of the light starter until the electricity is enough, and then it will be released at one time - it looks like the light is flickering. If the induced electricity on the zero line is large at this time, a current will continue to be generated on the line, causing the lamp to glow faintly.
It is difficult to eliminate the self-inductance current, and the recommended method is to consume this part of the power. The method is to buy a 220V AC relay, connect the relay coil in series with the lamp - use the relay coil to eliminate the self-inductive current.
The switch still conducts current after the switch is turned off
Some switches don't completely break the circuit when turned off, but still draw a small current in the circuit - I'm talking about switches with an indicator light. The indicator light of this kind of switch still needs to work after the switch is turned off, so although the switch is turned off, there is still a conductive part inside.
This part of the current is very small, so it will not have much effect on most lamps. However, if it is an LED light that is more sensitive to current, it may cause shimmering or flickering. There are two solutions at this time. The first is to connect a relay in series as mentioned above. The second is to remove the indicator light, or replace the switch.
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