Standard grounding resistance specification requirements:
1. The independent lightning protection grounding resistance should be less than or equal to 10 ohms;
2. The independent safety protection grounding resistance should be less than or equal to 4 ohms;
3. The grounding resistance of independent communication work should be less than or equal to 4 ohms;
4. The independent DC working grounding resistance should be less than or equal to 4 ohms;
5. The shared grounding body (joint grounding) should not exceed the grounding resistance by 1 ohm.
Purpose of grounding resistor:
It is an important parameter used to measure whether the grounding state is good, which is the resistance encountered when the current flows from the grounding device into the ground and then flows through the ground to another grounding body or diffuses to a distance. It includes the resistance between the grounding wire and the grounding body itself, the contact resistance between the grounding body and the ground, and the ground resistance between two grounding bodies or the ground resistance from the grounding body to infinity. The size of the grounding resistance directly reflects the good contact between the electrical device and the ground, and also reflects the scale of the grounding network.