A SUMMARY OF THE IEC PROTECTION AGAINST ELECTRIC-SHOCK

This paper provides a summary of the IEC protection against electric s hock. This protection is provided by appropriate basic measures as fol lows: 1) for protection both in: normal service and in case of a fault (against both direct and indirect contact), use low and safe voltage of 50 V and below; 2) for protection in normal service (against direct contact), use insulation and/or enclose live parts or use isolation d istance; and 3) for protection in case of a fault (against indirect co ntact), prevent conducting parts not normally energized from becoming live. This is accomplished by grounding and automatic disconnection of the supply, by use of Class II equipment las double or equivalent ins ulation), or by separating the supply from ground. IEC publication 364 -4-41 ''Electrical installations of buildings,'' (Part 4, Chapter 41) classifies types of system grounding as TN-system, TT-system, and IT-s ystem. Development of this summary is based on actual hazard risk anal ysis of potential incidents to suggest criterion by which the appropri ate measures can be applied to avoid or mitigate the injury or damage.