2. The protective zero line shall be laid separately and shall not be used for other purposes. In addition to the grounding in the power distribution room or distribution box, the grounding should be repeated at the middle and end of the line, and should be connected to the protective zero line, and the grounding resistance should not be greater than10Ω.
3. The cross section of the protective zero line should not be less than that of the working zero line, and must meet the requirements of mechanical strength. When the overhead laying distance of the protective zero line is greater than 12M, the protective zero line must be an insulated copper wire or an insulated aluminum wire less than 10MM2.
4. The cross section of protective zero line connected with electrical equipment should be insulated multi-strand copper conductor with a diameter of not less than 2.5MM2, and the unified sign of protective zero line is green/yellow double-color line. In any case, the green/yellow line is not allowed to be used as a load line.
5. Overhead lines shall have a span of not more than 35M and a distance between lines of not less than 0.3M Overhead lines shall be arranged in phase sequence: from left to right, the loads are L 1, N, L2, L3 and PE (note: L 1, L2 and L3 are phase lines, N is working zero line and PE is protection zero line).
6. Within an overhead line span, the number of joints of each layer of overhead lines shall not exceed 50% of the number of wires in that layer, and only one joint is allowed for one wire. Within the scope of crossing railways, highways, rivers and power lines, lines should not have joints.
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