ABSTRACT
Objective To study the protective earth requirement for touched metal parts of medical electrical equipment to improve the manufacturer's understanding on national standards.Methods The isolation methods for the touched metal parts in national standards were studied,and the principle of protective earth combined with insulation separating was analyzed.The characteristics of the second isolation method was discussed,and the respiratory system structure and electroshock protection of the anaesthetic machine were taken as examples.Results The touched metal parts with no measures for grounding,double isolation or reinforced insulation was determined by structure detection to meet the requirements of national standards in case basic insulation ceased to be effective and the parts were uncharged.Conclusion The necessities to girt the touched metal parts with measures for grounding,double isolation or reinforced insulation should depend on the understanding on national standards and electrical construction of the equipment under test by structure detection.