Test pen to measure neutral wire, live wire and ground wire
1. Turn on the power and use an electric pen to measure it. The live wire will light up.
2. Disconnect the neutral wire, connect only the live wire, turn on the lights at home, and measure with an electric pen. The other one that will light up is the neutral wire.
3. The rest is the ground wire.
Neutral and ground wires are used directly
The electric pen cannot test it. They are not charged to the ground, so the test pen will not light up. The live wire can be tested with a test pen.
In the case where there is a residual current protection device (leakage circuit breaker), the live wire and the neutral wire can be distinguished experimentally. A light bulb is connected between the live wire and the neutral wire. The bulb will light normally, and a light bulb is connected between the live wire and the ground wire. , the leakage circuit breaker will trip immediately.
Household electricity is generally single-phase electricity of 220V to 250V. The live wire passes through loads such as light bulbs and other electrical appliances, and then forms a loop through the neutral wire, so that the electrical appliances can work normally. Some electrical appliances with metal shells also need to be connected to a ground wire. When the electrical shell is accidentally charged, it can be led to the ground to ensure the safety of electricity.
In wire arrangement and daily maintenance, in order to distinguish wires for different purposes, wires of different colors are generally used to distinguish them.
Live wires generally use warm-colored wires, the most common being red wires. If you pursue a more standard construction, different circuits can use different colors of live wires to distinguish them. In addition to red wires, yellow wires and green wires can also be used. However, using multiple colors of wires to distinguish them will increase the cost of wire procurement to a certain extent.
The neutral line generally uses a cold-colored line, the most common one is blue, and some also use black lines.
According to the standard, the ground wire can only use yellow and green two-color wires. Since the ground wire is very important for electrical safety, the color requirements are very strict and cannot be replaced by wires of other colors.
According to color
Red live wire, blue neutral wire, yellow and green two-color ground wire
If the colors cannot be distinguished
In practical applications, you are given three wires, one is the live wire, one is the neutral wire, and one is the ground wire. If the three wires are the same color! How can you tell the difference?
1. The correct connection method is: the phase wire (L) is generally red or brown; the neutral wire (N) is blue or green; the protective earth wire (PE) must be yellow and green.
2. When using an electric pen to measure live wires, will you use a clamp-on ammeter? The current in the phase wire (live wire) and the neutral wire are the same, and there is no current in the ground wire normally.
3. The neutral wire has current flowing through it; the ground wire is for protection. There is no current during normal operation. There is current only when there is a short circuit or leakage. The grounding resistance is required to be very small. The equipment end is generally protected and grounded by the shell.
Use an electric pen to measure the live wire, and place the test light (wired light bulb) on the live wire and one of the other two wires. If the light is on, it means the 0 wire. If the light is on or not. It says it's a ground wire. (The light test method is effective when the ground wire is not connected to the earth. If the ground wire is connected to the earth, the light will turn on no matter which wire is connected.)
4. When there is a power supply, it should not be difficult to find the live wire. The difficulty lies in distinguishing the neutral wire and the ground wire. Theoretically speaking: the voltage between the live wire and the neutral wire is to the right of 220, and the voltage between the ground wire Around 190 volts. If you connect an energy-saving lamp, you should be able to tell the brightness. The bright one is naturally the neutral line, for reference only.
5. There is a simple way
We use a test light (wired light bulb) to connect the live wire and one of the other two wires. If the light is on, it means the 0 wire. If the light comes on, the leakage switch will trip. It says it's a ground wire.
