The switch controls the live wire and uses a test pen to test the neutral wire. Why is there a slight light?
First of all, it should be clear that no matter whether the live wire (the technical term is the phase wire) is disconnected or not, the neutral wire will not be charged under normal circumstances. If the neutral line is live, it means there is a problem somewhere on the line. So how to find out where the problem is? For ordinary electricity customers, let's share a simple and practical quick search and processing method:
1. Regarding the description of this problem, because the neutral line is slightly bright, the cause of this phenomenon is generally oxidation at the overlap of the neutral line, resulting in poor contact. However, this situation can be ruled out as a disconnection of the neutral line of the main line. , because the neutral line of the main line is disconnected or has poor contact, the fault phenomenon and consequences are different, and will not be analyzed here.
2. Search in sections and narrow the scope. First, check whether the neutral line on the upper and lower pile heads of the switch is normal when the main switch is in the closing position. If the neutral line is normal and has no power, it is usually a problem in the rear section of the switch. You can check the joints on the line section by section. After finding the fault point, just rewire and bandage it. Because the problem is usually at the line connection. This situation occurs most often with old power lines from a long time ago. Nowadays, indoor wiring and installation are very scientific, and this problem generally does not occur.
3. If when checking the switch to put the pile up and down, there is no power in the neutral line of the upper pile head, but there is power in the lower pile head. In this case, the switch is usually broken. You can turn the switch on and off several times, and sometimes the power can be restored temporarily, but you should still Replace the switch promptly.
During the inspection, if the neutral line on the pile head of the switch is also live, in this case, you can usually only call for repair, because there may be a pole inspection, and the user cannot easily solve it.
There are two possibilities. First, in order to allow users to find the switch position smoothly in the dark, some wall switches have an indicator light connected across the switch. When the switch is turned off, the indicator light still remains. A small current passes through the switch. Second, any fluorescent lamp, whether it is an ordinary fluorescent lamp or an energy-saving lamp, has a certain delayed extinguishing characteristic of its phosphor, which is called "afterglow". Nowadays, science has advanced. With LCD monitors and corresponding display circuits, things that do not happen at the same time can be easily displayed on the same screen. For example, an electrocardiogram monitor displays a horizontal line that fluctuates up and down with the beating of the heart. In fact, all the fluctuations on this horizontal line do not happen at the same time, but have a time process. In the past, when there were only CRT monitors, only one point fluctuated with the beating of the heart. In order to display a line, a "long afterglow" monitor had to be used, so that the scanning point would not go out immediately after passing by, but would reappear after a long period of time. Slowly extinguishing it will turn the movement of a point into the display of a line. The oscilloscopes at that time also worked on the same principle.
The neutral line is the circuit of all electrical equipment. Since the neutral line has a certain resistance, the greater the resistance of the neutral line or the greater the current of the neutral line, the higher the corresponding voltage above it. Therefore, the neutral line does not have no voltage at all, and it is possible that the test pen is slightly bright. Of course, if there is poor contact in the neutral circuit, etc., the neutral voltage will be high. So it is best to use a voltmeter to measure the voltage.
If the fuse of one phase of the transformer is broken, it will also cause the neutral line to light up slightly when measured with an electric pen. When a motor is burned out and a phase on the line far away passes through the motor and is grounded, it will also cause the neutral line to light up slightly when measured with an electric pen. When the neutral line is disconnected and the power is passed through the electrical appliance, it will also detect that the neutral line is charged and the electric pen will be brighter.
It's very simple. As long as the neutral circuit is well connected, this phenomenon is unlikely to occur. If this phenomenon occurs, there must be a disconnection or poor conduction somewhere in the neutral circuit, or electrical appliances may be connected in series. The solution is to firmly connect the disconnected or poorly conducted parts of the neutral circuit. If two electrical appliances are connected to a circuit, cut off one electrical appliance and keep only one electrical appliance.
