How to use the test pen correctly and precautions
The test pen, referred to as the electric pen, is a common tool used to check and measure whether the low-voltage electrical conductors and the electrical equipment casing are charged.
The test pen is often made into a pen structure or a small screwdriver structure. Its front end is a metal probe, the rear plastic shell is equipped with neon bulbs, safety resistors and springs, and the tail end has a metal end cap or a pen-shaped metal hanging nose, which is a metal part that must be touched by hands during use. The measuring voltage range of ordinary test pens is between 60 and 500 volts. When it is lower than 60 volts, the neon bulb of the test pen may not emit light. If it is higher than 500 volts, ordinary test pens cannot be used to measure, otherwise it is easy to cause personal electric shock.
When the nib of the test pen touches the charged body, the voltage on the charged body passes through the nib (metal body), neon bubble, safety resistor, spring and metal body at the end of the pen, and then connects to the earth through the human body to form a circuit. If the voltage between the charged body and the earth exceeds 60 volts, the neon bulb in the test pen will emit light, indicating that the object under test has electricity.
When using the test pen, pay attention to the following:
(1) Before using the test pen, first check whether there is a safety resistor in the test pen, and then visually check whether the test pen is damaged, whether it is damp or watered, and whether it is broken, and can only be used after passing the inspection.
(2) When using the test pen, never touch the metal probe at the front end of the test pen with your hands, otherwise, it will cause personal electric shock accidents.
(3) When using the test lead, be sure to touch the metal part at the end of the test lead with your hands. Otherwise, because the electrified body, the test pen, the human body and the earth do not form a circuit, the neon bulb in the test pen will not emit light. This will cause misjudgment, thinking that the charged body is not charged, which is very dangerous.
(4) Before measuring whether the electrical equipment is charged, first find a known power source for testing, and check whether the neon bulb of the test pen is normally glowing. It can only be used if it can emit light normally.
(5) When testing the charged body under bright light, special attention should be paid to whether the neon bulb is really glowing (or not). If necessary, the other hand can be used to block the light and judge carefully. Do not cause misjudgment, judge that the neon bulb glows as not glowing, and judges that there is electricity as no electricity.
