Why is the zero line slightly bright when tested with an electric pen
Firstly, it should be clarified that regardless of whether the live wire (the professional term is the phase wire) is disconnected or not, the zero wire will not be charged under normal circumstances. If the zero line is live, it indicates a problem somewhere in the line. How can we identify the problem? For ordinary electricity customers, share some simple and practical quick search and processing methods:
1、 In response to this problem description, the reason for this phenomenon is generally due to oxidation phenomenon at the overlap of the zero line, resulting in poor contact. However, this situation can be ruled out as a problem of main line zero line disconnection, as the fault phenomenon and consequences caused by main line zero line disconnection or poor contact are different. We will not analyze it here.
2、 To search and narrow the scope in sections, first check whether the zero line on the upper and lower pile heads of the switch is normal when the main switch is in the closed position. If the zero line is normal and has no power, it is usually a problem with the rear section of the switch. You can check the joints on the line section by section, find the fault point, and then rewire and wrap it. Because the problem usually occurs at the line connection. The most common occurrence of this situation is usually the old power lines from a long time ago. Nowadays, indoor wiring and installation are very scientific, and this problem usually does not occur.
3、 If there is no power on the zero line of the upper pile head and no power on the lower pile head when checking the upper and lower piles of the switch, this situation is usually due to the switch being broken. You can open and close the switch several times, and sometimes it can temporarily restore power, but you should still replace the switch in a timely manner.
If the zero line on the switch's pile head is also live during inspection, this situation can generally only be reported by calling for repair, as there may be pole climbing inspection, which users cannot easily solve.
There are two possibilities. Firstly, some wall switches have an indicator light connected across the switch to allow users to find the switch position smoothly in the dark. When the switch is turned off, there is still a small current flowing through the indicator light. Secondly, all fluorescent lamps, whether ordinary fluorescent tubes or energy-saving lamps, have a certain delayed extinction characteristic of their fluorescent powder, called "afterglow". Now that science has advanced, with liquid crystal displays and corresponding display circuits, it is easy to display things that do not happen simultaneously in the same screen. For example, an electrocardiogram monitor displays a horizontal line that fluctuates up and down with the beating of the heart. However, in reality, all fluctuations on this horizontal line do not occur at the same time, but have a time process. In the past, when there was only a CRT display, only one point fluctuated with the beating of the heart. In order to display a line, a "long afterglow" display had to be used, so that the scanning point did not immediately turn off after passing, but gradually turned off after a long period of time, making the movement of a point become a display of a line. And the oscilloscope at that time also had the same principle.
The zero line is the circuit of all electrical equipment. Due to the presence of a certain resistance in the zero line, the higher the resistance or current of the zero line, the higher the corresponding voltage above it. So the zero line is not completely devoid of voltage, and it is also possible for the measuring pen to be slightly bright. Of course, if there is poor contact in the zero line circuit, it will cause the zero line voltage to be too high. So it's best to use a voltmeter to measure the voltage.
A broken fuse in one phase of the transformer can also cause the zero line to light up slightly with an electric pen. When a motor is burned out and a phase is grounded far away from the line, it can also cause the zero line to light up slightly with an electric pen. When the zero line is disconnected from the power supply, it will also be measured through an electrical appliance that the zero line has an electric pen that is relatively bright.
Simply put, as long as the zero line circuit is well connected, this phenomenon cannot occur. If this phenomenon occurs, it is certain that there is a disconnection or poor continuity in the zero line circuit at some point, or there is a connection to the electrical appliance. The solution is to firmly connect the parts of the zero line circuit that are disconnected or have poor conductivity. If two electrical appliances are connected in a circuit, one electrical appliance should be cut off and only one electrical appliance can be retained.
