Why is there no light coming from the test pen when it measures the zero line?
The neutral wire is linked in series with the live wire and the electrical appliance, allowing the current to flow through while still being equal to the current in the live wire because of the series connection. Test it using an ammeter if you disagree with what I'm saying. The reason it cannot be identified with the electric test pen is fairly straightforward: the electric test pen can only determine whether the conductor is connected to the live wire or to distinguish between the live and neutral wires. It cannot determine whether there is current.Since there is a 220V voltage difference between the live wire and the earth, there is a weak current flowing from the live wire through the test pencil and the human body when the metal body of the test pen tip makes contact with a live wire or conductor connected to a live wire. The neon tube of the test pen emits light as it flows to the earth, but the current there 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.
How to use the digital display test pen?
Answer: The correct use of the digital display test pen should master the following:
(1) Button description:
(A key) DIRECT, direct measurement button (far away from the LCD screen), that is, when using the pen tip to directly touch the line, please press this button.
(B key) INDUCTANCE, inductive measurement button (closer to the LCD screen), that is, when you use the tip of the pen to sense the contact line, please press this button.
Note: Regardless of how to print on the electric pen, please remember that the one farther from the LCD screen is the direct measurement key; the one closer to the LCD is the sensor key.
(2) The digital display test pen is suitable for direct detection of 12-250 V AC and DC and indirect detection of neutral wire, phase wire and breakpoint of AC power. It can also measure the continuity of dead conductors.
(3) Direct detection:
①The last number is the measured voltage value.
②When the display value of high cut-off is less than 70%, it will display low cut-off value.
③ When measuring direct current, touch the other pole with your hand.
(4) Indirect detection: Press and hold the B key, and bring the pen tip close to the power line. If the power line is charged, the display of the digital display pen will display a high voltage symbol.
(5) Breakpoint detection: hold down the B key and move longitudinally along the wire, the place where there is no display in the display window is the breakpoint.
