Whether the grounding protection of the distribution box in the steel structure factory building can be connected to the steel column depends on the wiring method.
If it is a three-phase five-wire system, there is a special protective ground wire (PE wire, yellow and green). The distribution box shell should be connected to the PE wire and can also be connected to the steel structure.
If it is a three-phase four-wire system, whether the distribution box shell can be connected to the steel column depends on the grounding condition of the steel structure. If the steel structure is installed on a cement base, reliable grounding measures must be taken for the steel structure before connecting it to the distribution box shell.
Factory buildings and transformers cannot use only one grounding point. Otherwise, separate reliable grounding measures should be taken for the distribution box shell.
Extended information:
The basic principle of ground protection is to limit the leakage current of leakage equipment to the ground so that it does not exceed a certain safety range. Once it exceeds a certain setting value, the protector will Can automatically cut off the power supply.
The grounding protection system only has phase lines and neutral lines. Three-phase power loads do not need a neutral line. Just ensure that the equipment is well grounded. The neutral line in the system is except for the neutral point of the power supply. , there must no longer be a ground connection. If the public power distribution network is a TT system, grounding protection should be adopted uniformly.
Baidu Encyclopedia--Grounding Protection
Baidu Encyclopedia--Grounding