Several common uses of measuring electric pens
The test pen is almost one of the most commonly used tools by electricians, and for ordinary users, a two yuan test pen has long been a must-have tool for families, just like a screwdriver and pliers. But how should the test pen be used?
1. Basic usage
The various functions of a test pen cannot be separated from the correct use method - for electric pens, if the use method is incorrect, there may even be a risk of electric shock, so it is necessary to be cautious.
Here we will only talk about the usage of the most common and cost-effective neon bubble measuring pen:
Clamp the insulated part of the test pen between the thumb, middle finger, ring finger, and little finger (thumb on one side, and the other three fingers on the other side), and touch the metal cap or clip at the top of the pen with the index finger.
At the other end of the test pen, there is something similar to a screwdriver, which can only come into contact with the object being tested and must not come into contact with the human body.
When measuring, hold the electric pen in the above posture and use the screwdriver to partially contact the measured object. At the same time, it is necessary to ensure that the body part of the measurer is in contact with the ground (standing directly on the ground, if wearing insulated rubber shoes or standing on a stool, the other hand needs to be in contact with the wall).
2. Measure voltage
Measuring voltage with an electric pen is the most common use of an electric pen. However, it should be noted that the measuring pen can only measure the presence or absence of voltage in the circuit, and cannot determine the on/off or voltage magnitude of the circuit (having voltage is definitely a path, but not having voltage is not necessarily an open circuit).
When measuring, use a measuring pen to contact the measured circuit. If the measuring pen lights up, it indicates that there is voltage in the circuit; On the contrary, there is no voltage.
Before measuring, we first need to know the purpose of our measurement. For example, in single-phase circuits, under normal circumstances, the live wire has voltage, while the zero wire and ground wire have no voltage. Therefore, under normal circumstances, the live wire can light up the pen, while the zero ground wire cannot light up. But when we measure that the zero ground wire cannot light up the pen, it does not mean that the zero ground wire is completely normal and further testing is needed.
3. Distinguish between zero and ground wires
Distinguishing between zero and ground wires has always been a headache for many novice electricians. But in fact, a measuring pen can solve this problem.
The method is as follows:
Firstly, use an electric pen to measure the several wires in front of each other. Only one wire can light up the pen, and this wire is the live wire.
Afterwards, hold an electric pen in both hands, and the measurer stands on an insulated object, avoiding contact with the ground. Use one of the electric pens to make contact with the live wire, and the other pen to make contact with the line to be tested. If the two electric pens are not bright or have low brightness at this time, the line to be tested is the ground wire. If the two electric pens light up normally at this time, the line to be tested is the zero line.
4. Distinguish between positive and negative poles
By observing the luminescent position of neon bubbles, it is also possible to simultaneously determine the positive and negative poles of direct current.
As mentioned earlier, in direct current, neon bubbles only emit light at one end. If the neon bubble emits light at one end of the pen tip, the measured position is the positive pole of the power supply; On the contrary, it is the negative pole of the power supply.
In addition, some electricians say that when measuring whether two wires are the same item, they use two electric pens to hold one in each hand and simultaneously measure the two wires. If one is lit, it means the same item, and if both are lit, it means different items. It is particularly useful when connecting with several load lines of a device.
