Safety requirements for temporary electrical boxes and mobile cable reels at construction sites

Article 7.2.1 of the \"Technical Code for Safety of Temporary Electricity Use at Construction Sites\" JGJ46-2005 stipulates that cables must include all the working conductors as well as the conductors used as protective neutral wires or protective wires. Cable lines that require three-phase four-wire power distribution must use five-core cables. Section 8.1.1 stipulates that the power distribution system shall be equipped with distribution cabinets or main distribution boxes, sub-distribution boxes, and switch boxes, to implement a three-level power distribution system. The power distribution system should ensure balanced three-phase loads. Single-phase electrical equipment rated at 220V or 380V should be connected to a 220/380V three-phase four-wire system ； When the current in a single-phase lighting circuit exceeds 30A, it is advisable to use a 220/380V three-phase four-wire power supply.

Thank you for the guidance from the person on floor 2; I now enjoy reading national standards and technical specifications as well! Must the mobile cable reel have a three-pin plug? Mobile cable reels on site usually come equipped with leakage protectors and plugs in various specifications! It must be a three-prong plug; for some tools with double insulation that have only two prongs, it’s not convenient to use, right? This post was last edited by limingshuguang on 2008-1-8 08:32.]

I consulted an electrician; first, a five-core cable should be used for the distribution box. But the reality is that there aren’t many five-core cables available on the market nowadays; construction teams use four-core cables, namely L1, L2, L3, and N. Therefore, it is required that the construction teams add another wire outside the cable as a PE protection wire. II. Regarding mobile cable reels, the construction team sometimes uses Class 1 tools and sometimes Class 2 tools. If a Category 1 cable is used, a three-core cable must be employed. Therefore, all construction teams should use mobile cable reels with three-core corrosion-resistant rubber cables equipped with leakage protectors, and the plugs of such cable reels must be three-pole plugs.