Why does the test pen not emit light when measuring the zero line?
Not only does the current flow through, but it is also equal to the current in the live wire, because the neutral wire is connected in series with the live wire and the electrical appliance, and the current in each part of the series circuit is equal. If you don't believe me, test it with an ammeter. As for why it can't be detected with the electric test pen, it is very simple, because the electric test pen is used to distinguish the live wire and the neutral wire, or to judge whether the conductor is connected to the live wire, and cannot judge whether there is current. When the metal body of the test pen tip touches the live wire or the conductor connected to the live wire, a circuit is formed from the live wire through the test pen, the human body to the earth, because there is a 220V voltage between the live wire and the earth, there is a weak current from the live wire through the test pencil and the human body Flowing to the earth, the neon tube of the test pen emits light, but it is not the same as the current in the live wire. When the metal body of the pen tip of the test pen touches the zero line, since there is no voltage between the zero line and the earth, no current will flow through the test pen, and the neon tube of the test pen will not emit light.
The electric test pen distinguishes the live and zero wires of the 5 wires in the junction box
Two of the threads were wrapped with tape, that is, the red thread was covered with green tape, and the green thread was covered with yellow tape. The plumber made a mark when threading the wires. These two wires must represent a certain meaning. Next, I use a test pen and a multimeter to distinguish their live and zero wires.
The detection method of the electric pen is as shown in the figure below. Use the electric pen to detect 5 wires to find out the live wire (generally red is the live wire). Or other) plug in, if the leakage protection trips, it means that the other wire is the ground wire, and if it does not trip, it means it is correct. If the C line and the DE line come from the same pipeline, it must be the ground line, and then connect the two lines of AB to the socket to see if the circuit breaker trips. can solve the problem
