Why are the neutral and live wires of advertising lights all 12 volts?
The live neutral line is a sign that there is no good grounding. If it is well grounded, the current will flow into the ground and the meter will not be able to detect it. come out.
1. The grounding resistance does not meet the process requirements, especially the grounding resistance of the neutral line is too large (the process requirements may be less than 1 ohm).
2. The PE wire does not meet the requirements. The cross-sectional area may be too small, or the line may be too long, the wire resistance may be too large, and the voltage drop at the measurement location may be large. Check whether the neutral grounding resistance meets the requirements (less than 1 ohm), and see whether the cross-sectional area of the PE (ground) wire is a little smaller or the line is a little longer.
3. The three-phase load is unbalanced, resulting in zero drift. The main reason is: Under normal circumstances, there should be no power on the neutral line. Therefore, once there is electricity, it must be a symptom of a fault; the simplest one is electromagnetic induction, and at this time, the neutral line is not well grounded and cannot form a loop; secondly, the electrical equipment leaks or the phase wire hits the shell, but the current is not large. , so it has not tripped yet.
Extended information
The neutral line is mainly used in the working circuit, which is the main line drawn from the neutral point of the generator and transformer and grounded.
The ground wire is not used for the working circuit and is only used as a protection wire. Utilizing the absolute "0" voltage of the earth, when leakage occurs in the equipment shell, the current will quickly flow into the earth. Even if the PE line is open-circuited, it will flow into the earth from the nearby grounding body. (After grounding the neutral point of the transformer, lead out the main line and repeat the grounding every 20-30 meters)
There are also ground wires connected to electrical appliances - wires connected to the earth; live wires, neutral wires, and ground wires They are all wires connected to the three-hole socket, and a sinusoidal oscillating voltage difference is maintained between the live wire and the neutral wire. Since the earth and neutral wires have the same potential, the voltage difference between the live wire and the ground wire also maintains a sinusoidal oscillation. When the human body comes into contact with the live wire, the current from the live wire flows through the human body into the earth or the neutral wire, and an electric shock accident occurs. However, you will not be shocked if you touch the neutral wire.
Connect the shell of electrical appliances that can conduct electricity to the ground wire. In the case of leakage, the current will flow directly into the earth through the ground wire without passing through the body, thus avoiding electric shock accidents.