Why is the voltage between the neutral wire and the live wire 380V when measured by a multimeter?
The maximum possible reason for the voltage between the neutral line and the live line to be hidden at around 380V is that during the maintenance of the power supply and distribution line, a careless maintenance electrician accidentally connected the original single-phase 220V distribution neutral line to a phase line with a different phase sequence, causing the "neutral line" of the 220V voltage user to change to 380V voltage on the live line (although this situation is extremely rare, it cannot be ruled out that it may occur).
Some so-called "experts" without practical experience are enthusiastic about pretending to understand and answering electrical questions, believing that this is due to the open circuit of the neutral wire source in three-phase four (five) wire distribution, which leads to an extremely erroneous belief that the neutral wire has a voltage of 380V on the live wire. Because the neutral point displacement of the three-phase load caused by the open circuit of the neutral line source in the three-phase four (five) line distribution cannot be hidden within the same voltage value by the voltage of each phase to the user, and also because in such a situation where the neutral line source is disconnected; The electrical appliances turned on by users of different phase sequences will form circuits between phase lines of different phase sequences through the electrical appliances turned on by users of different phase sequences, so the voltage at both ends of the electrical appliances will constantly change due to the different load sizes of each phase.
that is; If the neutral point displacement of the three-phase load is caused by a zero line source break in a three-phase four (five) line distribution, the voltage of the larger phase will decrease when the load is turned on (including automatic start stop devices such as fixed frequency air conditioners, refrigerators, etc.), the voltage of the smaller phase will increase when the load is turned on, and the voltage of the three phases will constantly change high and low as the load (electrical appliances) between the three-phase users is turned on and burned out, if not handled in a timely manner; Ultimately, the vast majority of all electrical appliances (equipment) in the entire distribution system will burn out.
I recently came into contact with three-phase AC power, and the potential difference between each phase wire and the neutral wire is exactly 220V, which is also the type used at home. The potential difference between phase wires is exactly 380V. In other words, it is highly likely that one of the phase wires in your home is connected to the neutral wire, resulting in a potential difference of 380V.
If this situation occurs at home, it is necessary to consider hiring power grid personnel to troubleshoot, otherwise the high voltage can easily burn out electrical appliances.
Whether this is the case can actually be easily judged by oneself. You can find an electric pen and insert it into two socket holes one by one to see if each socket has electricity. If there is electricity in all sockets, it is the situation I described, where the neutral wire is connected to the phase wire. I noticed that the main user measured the voltage with a multimeter, indicating that they have a multimeter at home. You can insert the red probe of the multimeter into the socket separately, but do not insert the black probe. However, try not to touch the black probe with your hands. If there is voltage in both sockets, it can also be concluded that this is the situation I mentioned.
