Several common uses of the test pen
1. Basic Usage
The various functions of the electric pen are inseparable from the correct method of use - for the electric pen, if the wrong method is used, there may even be a risk of electric shock, so be careful.
Here are just a few words about how to use the most common and cheapest neon bulb testing pencil:
Hold the insulated part of the test lead between your thumb and middle finger, ring finger, and little finger (thumb on one side, and the other three fingers on the other), and your index finger touches the metal cap or metal clip on the top of the test lead.
On the other end of the test pen, there is a thing like a screwdriver, this part can only be in contact with the object to be tested, and must not be in contact with the human body.
When measuring, hold the electric pen in the above posture, and touch the measured object with the above-mentioned flat screwdriver part. At the same time, it is necessary to ensure that the measurer's body part is in contact with the ground (just stand on the ground directly, if you are wearing insulating rubber shoes or standing on a stool, you need to touch the wall with the other hand).
2. Voltage measurement
Measuring voltage with a test pencil is the most common method for electric pencils. However, it should be noted that the electric test pen can only measure the presence or absence of voltage in the circuit, and cannot judge whether the circuit is on or off or the magnitude of the voltage (with voltage, it must be a circuit, but without voltage, it may not be an open circuit).
When measuring, touch the tested line with the electric test pen, if the electric test pen lights up, it proves that there is voltage in the line; otherwise, there is no voltage.
Before measuring, we must first know the purpose of our measurement. For example, in a single-phase circuit, the live wire has voltage under normal circumstances, and the neutral wire and ground wire have no voltage. Therefore, under normal circumstances, the live wire can light up the electric pen, but the neutral ground wire cannot light up. But when we measure the zero ground wire and the electric pen cannot be lit, it does not mean that the zero ground wire is completely normal, and further testing is required.
3. Distinguish between zero line and ground line
Distinguishing between neutral and ground wires has always been a headache for many beginner electricians. But in fact, a test pen can solve this problem.
Afterwards, hold an electric pen in each of the left and right hands, and the measurer stands on an insulating object, not in contact with the ground. Use one of the electric pens to touch the live wire, and the other electric pen to touch the line to be tested. If the two electric pens are not lit or the brightness is low at this time, the wire 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 AC and DC
Is the circuit alternating current or direct current? The same can be solved with a pencil.
Method 1: There are at least two wires in the circuit, measure with an electric pen, if one of the two wires can light up the electric pen, and the rest cannot light up, it proves that the circuit is AC. If there are two wires that can light up the electric pencil, it proves that the circuit is direct current.
Method 2: When the circuit is AC, the brightness of the electric pen is higher. When the line is DC, the brightness of the electric pen is low.
Method 3: Observe the light-emitting position of the electric pen. The same is to use the electric pen to touch the live wire. If it is direct current, the neon bulb inside the electric pen will only emit light at one end; if it is alternating current, the neon bulb inside the electric pen will light up. Methods as below:
First, use an electric pen to measure the several wires in front of you. Only one wire can light up the electric pen, and this wire is the live wire.
5. Distinguish between positive and negative poles
By observing the light-emitting position of the neon bulb, it is also possible to know the positive and negative poles of the direct current at the same time.
As mentioned above, in direct current, neon bulbs only emit light at one end. If the neon bulb emits light at one end of the pen tip, the measured position is the positive pole of the power supply; otherwise, it is the negative pole of the power supply.
In addition, some electricians say that to measure whether the two wires are of the same item, use two electric pens in each hand to measure the two wires at the same time, one is the same item, and both are different items. It is especially useful when combining several load lines with one device.
