1. Grounding resistance test requirements
Grounding resistance value: According to the "Construction Quality Acceptance Code for Building Electrical Engineering" GB 50303-2015, the grounding resistance value should meet the requirements of the design documents, and the grounding resistance should not be greater than 4 ohms.
Repeated grounding resistance: In a low-voltage power grid with direct grounding at the neutral point, the repeated grounding resistance should not be greater than 10 ohms.
Lightning protection grounding resistance: The grounding resistance for direct lightning protection is not greater than 10 ohms.
2. Test method
Test instrument: Use a grounding resistance tester for testing.
Wiring method: The wiring method of the grounding resistance tester should comply with regulations, usually including the green end connected to the green wire, the yellow end (voltage) connected to the yellow wire, the red end (current) connected to the red wire, the other end of the green wire connected to the grounding electrode PE of the object to be tested, and the other ends of the yellow and red wires are connected to the probes respectively, and the 3 wires should be kept in a straight line, and the voltage and current probes are 5 meters apart.
Test point selection: Each light pole should be tested at least once to ensure that the grounding resistance value meets the requirements.
3. Grounding device requirements
Grounding device specifications: The grounding device shall comply with the provisions of GB50169 "Construction and Acceptance Specifications for Grounding Devices for Electrical Installation Engineering", ensure sufficient mechanical strength, and meet the requirements of unbalanced current and harmonic current.
Grounding wire connection: The grounding wire should be reliably connected to metal equipment such as lamp poles and distribution boxes to form a grounding network.
4. Handling of special situations
Interference influence: When testing, try to avoid the direction of large interference to ensure stable instrument readings.
Test value accuracy: The accuracy of the test value is an important factor in judging whether the grounding is good. Once the test value is inaccurate, it may waste manpower and material resources or bring safety hazards to the grounding equipment.
5. Acceptance requirements
Acceptance criteria: The grounding resistance value should meet the requirements of the design documents. Generally, the grounding resistance should not be greater than 4 ohms.
Test records: The test data should be recorded truthfully to ensure that the data of each test point is accurate.
