What is the reason for the multimeter to show resistance when the circuit is short-circuited?
Before the first power transmission of the circuit, I always use a multimeter to measure whether there is a short circuit in the circuit before closing it. At this time, everything is normal. The multimeter does not beep and displays infinity.
After using it for a few months, during routine maintenance, a multimeter was used to measure the short circuit situation in the on/off range. When the probe was placed on two wires, it would beep and then there would be no sound. The multimeter screen displayed a resistance value of over 60 to 80.
So I can't figure out if this is a short circuit or not, and the circuit breaker can be closed, it feels inexplicable.
1. At first, there was no resistance between the two wires. However, when rechecked after using them for a period of time, there was resistance when the fire neutral wire was turned off, and the buzzer sounded. In my daily practice, I have seen this situation and my judgment is as follows:
2. The known condition is that there is no resistance between the wires when the indoor installation and debugging are handed over to the user for use. How did the user experience resistance between the wires when they are unloaded after using for a period of time? Is this a wire leakage? This phenomenon is the most sensitive issue for national electricians, 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. Old doctors know what disease they have when they hear a chief complaint, while young doctors rely on instruments.
3. I
The 400V infinite capacitor commonly used in energy-saving lamps is used as a resistor, and the neon tube starter on old fluorescent lamps is removed and connected in series as an indicator light, as this type 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 use electricity and accidentally touch it, there will be an electrical induction on your hand.
4. When retesting the resistance value, there were only two reflections, and it disappeared afterwards, as in the example I mentioned 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 (based on my experience, articles related to electricity all suggest unplugging all plugs and indicator lights). This is because the indicator light causes the fire neutral wire to be connected.
