How do I make sure the electric pen's zero and ground lines are correct?
How does the electric pen confirm the ground wire and zero wire? The electric pen measures the zero wire, live wire and ground wire
1. Turn on the power, use the electric pen to measure, the one that will light up is the fire wire.
2. Disconnect the neutral wire, only connect the live wire, turn on the light at home, measure with an electric pen, and the other one that will light up is the neutral wire.
3. The rest is the ground wire.
The neutral and ground wires are used directly
The electric pen can't be tested, they are not charged to the ground, so the test pen will not light up. The live wire can be tested with a test pencil.
In the case of a residual current protection device (leakage circuit breaker), the live wire and the neutral wire can be distinguished experimentally, and a bulb is connected between the live wire and the neutral wire, and the bulb glows normally, while a light bulb is connected between the live wire and the ground wire , the leakage circuit breaker will trip immediately.
Household electricity is generally 220V ~ 250V single-phase electricity. The live wire passes through the load such as light bulbs and other electrical appliances to form a loop through the neutral wire, so that the electrical appliances can work normally. Some electrical appliances with metal casings also need to be connected with a grounding wire. When the electrical casing is accidentally charged, it can be led to the ground to ensure the safety of electricity use.
In wire layout and daily maintenance, in order to distinguish wires for different purposes, wires of different colors are generally used to distinguish them.
Fire wires generally use warm-colored wires, the most common being red wires. If a more standard construction is pursued, different circuits can use different colors of live wires to distinguish them. In addition to the red wires, yellow wires and green wires can also be used. However, using multiple color lines to distinguish will increase the cost of wire procurement to a certain extent.
The zero line generally adopts a cool color line, the most common one is a blue line, and some also use a black line.
According to the standard, only yellow and green two-color wires can be used for the ground wire. Since the ground wire is very important to the safety of electricity use, the color requirements are very strict, and wires of other colors cannot be used instead.
by color
Red live wire Blue neutral wire Yellow and green two-color ground wire
if the colors are indistinguishable
In practical application, you are given three wires, one is live wire, one is neutral wire, and the other is ground wire, assuming that the colors of the three wires are the same! 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. Can you use a clamp-type ammeter to measure the live wire with an electric pen? The current of the phase wire (live wire) and the neutral wire is the same, and there is no current on the ground wire when it is normal.
3. The neutral wire has current flowing; the ground wire is used for protection, and there is no current in normal operation. Only when there is a short circuit and leakage, there is current. The grounding resistance is required to be small, and the equipment end is generally grounded for protection.
Use an electric pen to measure the live wire, put the test lamp (wired light bulb) on the live wire and one of the other two wires, if the light is on, it means the zero wire. If the light does not come on. Description is ground. (The lamp 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 be on no matter which wire is connected.)
4. In the case of 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, the voltage between the live wire and the neutral wire is on the right side of 220, and the voltage between the ground wire Around 190 volts. If you connect an energy-saving lamp, you should be able to see the brightness and darkness. The bright one is naturally the neutral line, which is for reference only.
5. There is another simple way
We use a test lamp (a light bulb with a wire) to connect the live wire and one of the other two wires. If the light is on, it means that it is the 0 wire. If the light is on, the leakage switch will jump. Description is ground.
