The temporary power transmission lines for the construction site are laid using buried cables or partially overhead wiring.
(2) During cable laying, the following requirements apply: ① When the cable passes through buildings, roads, etc. on the construction site, or when it is led out from the ground to a depth of 2m or extended to a depth of 0.2m underground, a protective conduit with a smooth inner wall and no burrs must be installed. The pipe opening should be sealed. ② The parallel distance between the cable and the nearby thermal pipelines should be no less than 2m, and the crossing distance should be no less than 1m. ③ Cable joints should be placed inside protective boxes to ensure waterproofing, dustproofing, firmness and reliability. Insulation wrapping should be done in accordance with specifications to ensure insulation strength and prevent the cable from bearing external forces. ④ When overhead laying of rubber cables is carried out, they should be set along walls or poles and fixed with reliable insulation. Metal bare wires should not be used for binding. The spacing between the two fixed points should ensure the load that the cable can bear. The maximum sag distance from the ground (floor) should not be less than 2.50m.
(3) For the temporary power distribution main lines at the construction site, if they are laid overhead, insulated copper (aluminum) wires must be used and they should be erected on dedicated poles (structures). It is strictly prohibited to lay them on trees or other objects that may cause damage to the wires or lead to electrical conductivity.
(4) The poles are made of concrete poles or wooden poles. The concrete poles must have no exposed rebars or cracks; the wooden poles must not be rotten or deformed, and their top diameter must be no less than 13 cm.
(5) According to the mechanical strength requirements of the conductors, the cross-sectional area of the insulated copper wire should be no less than 10 mm²; the cross-sectional area of the insulated aluminum wire should be no less than 16 mm². When crossing railways, major roads, or navigable rivers, for power lines within the span: for overhead insulated wires, the minimum cross-sectional area of the copper wire should be no less than 16 mm²; for aluminum wires, it should be no less than 35 mm² of a multi-strand conductor. Crossing height: When overhead lines cross railways or roads, the maximum sag with the road surface should not be less than 6 meters.
(6) For the temporary wiring at the site, the usage period should be clearly defined. Once the period expires, it must be immediately removed. (7) For the temporary power supply of high-rise buildings, it is necessary to introduce the power cables through buried conduits. The vertically laid cables should be protected by steel sleeves using the vertical shafts or vertical holes of the construction project, and should be as close as possible to the power load center. There should be no less than one fixed point per floor. For the horizontal laying, it is advisable to fix along the wall, and the distance from the floor level should be no less than 1.8 meters.