**Testing Method for Lightning Protection Grounding Tester in Henan School Project**
**Grounding Resistance Test Requirements:**
a. AC working grounding resistance should not exceed 4Ω.
b. Safe working grounding resistance should also be no more than 4Ω.
c. DC working grounding resistance is determined based on the specific requirements of the computer system.
d. The grounding resistance of the lightning protection system should not exceed 10Ω.
e. For shielded systems, the grounding resistance should be less than or equal to 1Ω.
**Grounding Resistance Tester – ZC-8 Model**
The ZC-8 grounding resistance tester is a versatile tool used to measure the resistance of various power systems, electrical equipment, and lightning protection devices. It can also measure low-resistance conductors and soil resistivity, making it ideal for a wide range of applications.
**Instrument Structure**
The ZC-8 consists of a hand-cranked generator, current transformer, sliding wire resistor, and a galvanometer. All components are housed in a durable plastic case that is easy to carry. The instrument comes with auxiliary probes and wires, which are stored in a separate bag for convenience. Its working principle is based on the reference voltage comparison method, ensuring accurate readings.
**Preparation Before Use**
Before starting the test, ensure the following components are included:
1. One ZC-8 grounding resistance tester
2. Two auxiliary grounding rods
3. Three wires of 5m, 20m, and 40m in length
**Usage and Operation**
(1) When measuring grounding resistance, connect the E terminal to the 5m wire, the P terminal to the 20m wire, and the C terminal to the 40m wire. The other ends of these wires should be connected to the grounding electrode (E'), potential probe (P'), and current probe (C'). These three probes should be placed in a straight line, spaced 20 meters apart.
(2) For measurements below 1Ω, connect both E-terminal wires directly to the grounding body being tested to eliminate errors caused by the resistance of the connecting wires.
**Operation Steps**
(1) Ensure all wiring connections are correct.
(2) Make sure the instrument's wires are firmly connected to the grounding electrode, potential probe, and current probe.
(3) Place the meter on a flat surface and adjust the galvanometer to its mechanical zero point.
(4) Set the "multiplier switch" to the highest position and gradually increase the crank speed to 150 revolutions per minute. If the galvanometer pointer moves, adjust the dial until it returns to "0." The measured resistance value is the dial reading multiplied by the multiplier.
(5) If the dial reading is less than 1 and the galvanometer remains unbalanced, lower the multiplier step by step until balance is achieved.
(6) If the galvanometer pointer shows instability, adjust the crank speed to stabilize the reading.
**Important Notes**
1. Never perform tests during thunderstorms or when the object under test is energized.
2. Handle the instrument carefully to avoid shocks or vibrations that could affect accuracy.
**Henan School Lightning Protection Project – Grounding Tester Test Method**
For detailed procedures and safety guidelines, refer to the manufacturer’s manual and local regulations. Proper grounding is essential for protecting the school's infrastructure from lightning damage.
**Source:** China Hardware Business Network | http://news.chinawj.com.cn
**Image Credit:** [Test method of lightning protection grounding resistance tester for lightning protection project of Henan school](http://i.bosscdn.com/blog/91/01/30/25678.jpg)
**Editor:** Hardware Business Network Information Center | http://news.chinawj.com.cn
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