What are the requirements for grounding lead wires of transformers and main equipment?

1. grounding lead; galvanized round steel should be not less than 12mm in diameter, galvanized flat steel should be 40mm * 4mm or more, 2. capacity greater than 200kva or more should be set up 2 grounding lead, 3. grounding lead and grounding body reliable electrical connection, and grounding electrode connecting line should be buried deep below the permafrost layer, 4. grounding impact resistance (if lightning protection, neutral point, protection of the three kinds of grounding ****with ) should be; 100kva and above is less than or equal to 4 ohms, 100kva below can be below 10 ohms.