Ground wire role:
1, protection of electrical appliances, static electricity in the discharge process will produce a large number of charges, if the electrical appliances do not have the appropriate barrier will be on the electrical appliances and damage, the role of the ground wire is the role of the electrical appliances and the ground under the ground between the wires, can effectively avoid electrical appliances are strong charge damage.
2, lightning, before if the occurrence of lightning poles and electrical equipment are easily damaged by lightning strikes, so now will be grounded, so you can prevent lightning, to avoid damage to electrical appliances.
3, to protect the normal work of the machine, a lot of electrical appliances is necessary to electricity to work, especially in the medical field, the role of the ground wire is to be able to avoid a sudden power outage will not be affected, you can run some of the small load potential.
4, the protection of human safety, if the human body electrocution occurs, the ground can lead the current to the ground so that the current through the human body will be much smaller, thus protecting the safety of human life.
Earth wire selection:
1, the cross-section of the grounding wire to meet the requirements of the short-circuit current, not less than twenty-five millimeters two requirements, so the selection of the cross-sectional area should be large enough conductive metal material line with good performance.
2, to meet the requirements of the short-circuit current heat capacity, in the case of a short-circuit, it will be through the ground in time to act on the circuit breaker tripped, and the heat generated by the short-circuit current will not melt it off.
3, grounding line has a good flexibility, and wear-resistant and not easy to rust, are generally selected multi-stranded soft bare red copper wire to make the grounding line, otherwise the lot will be unprotected and make the accident expand.