There are three ways to measure if the earth wire is making good contact:
1, multimeter measurement, multimeter is also known as multipurpose meter, multi-meter, three with the meter, complicated with the meter, etc., is the power electronics and other departments indispensable measurement instrument, generally to measure voltage, current and resistance as the main purpose.
Usage: When measuring, rotate the gear knob to select to the correct gear (250V~). After that, insert the black meter pen into the COM jack and the red meter pen into the jack marked with "V". Hold the meter with one hand and the two pens with the other hand like chopsticks - only plastic rods should be held, not the wires and not the front metal. Touch the two pens to the two wires to be tested.
Judgement method: the voltage between the zero fire line and the ground and the voltage on the fire line is the same or slightly larger (not more than 5V), proving that the ground is well grounded, and the smaller the difference between the two, proving that the grounding resistance is smaller. Conversely, the grounding body failure.
2, light bulb measurement, beforehand to deal with the bulb, connect two wires to, in order to operate after - if there is an unused lamp port can be directly installed in the lamp port on the bulb can be, after the bulb were connected to the zero line and the fire wire, ground and between the fire wire (remember to disconnect the power when connecting the line), to observe the brightness of the bulb, and analyse the results.
In the case of a well grounded earth wire, the bulb has the same brightness twice. If the ground is faulty, the bulb does not light up. If the grounding resistance is only slightly larger, then the bulb is only slightly darker.
3, grounding resistance tester, generally speaking, in the project acceptance, will use this equipment for testing. Ground resistance tester, can accurately measure the size of the ground resistance of the earth wire. Generally our family with the ground, as long as the grounding resistance is not greater than 4 ohms even if qualified.
The basic functions of the multimeter:
1, Measurement: resistance, AC and DC voltage, AC and DC current, on and off.
2, expansion: capacitance, inductance, diode, transistor.
Multimeter has a multi-purpose, wide range, easy to use and other advantages, is the most commonly used tools in electronic measurement. It can be used to measure resistance, AC and DC voltage and DC voltage. Some multimeters can also measure the main parameters of the transistor and the capacitance of the capacitor. Mastering the use of multimeter is a basic skill of electronic technology.
3, the common multi-meter pointer multi-meter and digital multi-meter. Pointer multi-meter is a head for the core components of the multi-function measurement instrument, the measured value by the head pointer indication reading. Digital multimeter measurement value by the liquid crystal display directly in the form of digital display, easy to read, some also with voice prompts.
4, the DC current file of the multimeter is a multi-range DC voltmeter. The head of the meter can be connected in parallel with a closed-circuit voltage divider resistor to expand its voltage range. The DC voltage of the multimeter is a multi-range DC voltmeter. The voltage range of the multimeter can be enlarged by connecting a voltage divider resistor in series with the head of the meter. Different voltage divider resistors have different ranges.
