Electrocution and Fires Involving 120/240-V Appliances

The most serious accidents with 120/240-V appliances are probably those involving electric shock and fire. To aid in the investigation of such incidents, some fundamental concepts are presented for the accident investigator. For electric shock cases a knowledge of the effects of electricity on the human body and the electrical parameters related to these effects is important. Since most shock cases involve a question as to the path of current to ground or whether the grounding was proper, present day grounding procedures are described for appliances. To aid in investigations of accidents involving older equipment or systems, a history of the National Electrical Code´s (NEC) grounding requirements and allowable use of double insulation for cord- and plug-connected equipment is included. In the investigation of fires of possible electrical origin, the investigator is usually confronted with arc damage that either caused the fire or was caused by the fire. A discussion of the fundamentals of electric arcs and of circuit protection is presented to aid in this determination.