What is the reason why a multimeter shows resistance when measuring a short circuit in a circuit
The situation is like this, I have encountered it many times:
Before the first power transmission of the circuit, I always use a multimeter to check whether there is a short circuit in the circuit before closing it. At this point, everything is normal, the multimeter has no beeping sound and displays infinity.
After using it for a few months, during routine maintenance, when using a multimeter to measure the on/off range and short circuit, if the probe is connected to two wires, it will beep once, and then there will be no sound. The multimeter screen shows a resistance value of over 60 to 80.
So it's unclear whether this is a short circuit or not, and the switch can be closed, it feels inexplicable.
1. At first, there was no resistance value between the two wires. However, when I checked again after using it for a period of time, when I turned off the fire zero wire, there was actually a resistance value, and the horn beeped. In my usual practice, I have seen this situation, and my judgment is as follows:
2. Given that the condition is that there is no resistance value between the lines when they are installed and debugged indoors and handed over to the user for use, how can the user experience resistance values between the lines after using them for a period of time? Is this a wire leakage? This phenomenon is the most sensitive issue for official electricians in the country, and their first reaction is to use a megohmmeter. Without a megohmmeter, the problem cannot be detected. This phenomenon is similar to that of old doctors and young doctors. When an old doctor hears a chief complaint, he knows what disease it is, while young doctors rely solely on instruments.
3. I often use the 400V stepless capacitor on energy-saving lamps as a resistor, and remove the neon tube starter from the old fluorescent lamp and connect it in series as an indicator light, because this form of indicator light has been seen in mobile sockets. The characteristic of an infinite capacitor is that it can store a certain amount of charge. If you pass through electricity, do not pay attention to the induction of electricity to human hands when touched.
4. When retesting the resistance value, there were only two reflections, and it disappeared afterwards, as I mentioned in the example above.
5. When there is a mobile socket on the user's wall socket, there is a switch and indicator light on the mobile socket. After turning off the main power, the mobile socket is not unplugged. (My experience summary, articles on electricity all remind you to unplug all plugs and indicator lights) It is this indicator light that causes the fire neutral line to be connected.
