Why does the zero line of the measuring pen not emit light
Not only is there current passing through, but it is also equal in magnitude to the current in the live wire, because the zero wire is connected in series with the live wire and the consumer, and the current in the series circuit is equal everywhere. If you don't believe it, use a Ammeter to measure it. As for why it cannot be measured with a measuring pen, it is simple because the measuring pen is used to distinguish between the live wire and the zero wire, or to determine whether a conductor is connected to the live wire, and cannot determine whether there is current. When the metal body of the stylus tip contacts the live wire or a conductor connected to the live wire, a circuit is formed from the live wire through the stylus, the human body, and the ground. Because there is a 220V voltage between the live wire and the ground, a weak current flows from the live wire through the stylus and the human body to the ground. The neon tube of the stylus emits light, but it is not the same as the current in the live wire. When the metal body of the stylus tip contacts the zero line, there is no voltage between the zero line and the ground, so no current flows through the stylus, and the neon tube of the stylus does not emit light.
Measure the zero wire of 5 wires in the junction box of the electric pen and multimeter
Two of the wires were wrapped in adhesive tape, namely red wire green adhesive tape and green wire yellow adhesive tape. The water electrician marked the wires when threading them, and these two wires definitely represent a certain meaning. Below, I will use a measuring pen and a multimeter to distinguish their fire zero wires
Use an electric pen to test 5 wires separately and identify the live wire (usually red is the live wire). For example, if the E red wire is the live wire, then connect the DE two wires to the socket and use a desk lamp or charger (mobile phone or other) to insert them. If there is a missed protection trip, it means the other wire is the ground wire, and if there is no trip, it means it is correct. If the C line comes from the same pipeline as the DE line, it must be the ground wire. Then, connect the AB lines to the socket and observe if the circuit breaker trips.
The method of detecting wires with a multimeter is because the live wire is 220V from zero to ground. First, identify the three wires and set the multimeter to an AC voltage range of 200V, as shown in the figure. Wrap the probe in your hand for a few turns, and the other one contacts the wire. If the voltage is high, it is the live wire, if the voltage is low, it is the zero wire, and if there is no voltage, it is the ground wire. After confirming the three wires, measure the voltage of the two wires and the live wire separately. If not, insert them separately.
