Electric Shock Hazard

 

Like the bird perched on a high-tension wire, the human body is immune to shock so long as it is not part of the electric circuit. Recent standards and safety practices guard against this contingency but their effectiveness varies with the individual’s vulnerability and environment.

 - Charles F. Dalziel

 

Dalziel, a long-standing expert on electric-shock hazards summarizes the studies that determined the effective body impedance under varying conditions. He describes perception currents, reaction currents, let-go currents, and fibrillating currents. Turning to means for reducing low-voltage (120-240 volt) hazards, double insulation, shock limitation, isolation transformers, and the use of either high frequency or direct current discussed for various environments. Macroshock is always a hazard in the home, in industry, and in the hospital. But the extreme vulnerability to microshock of patients with cardiac catheters, for example, requires special precautions in intensive-care and coronary-care units. Equipment such as the ground-fault interrupter (GFI) and a special isolation transformer are cited.

 

Click here to review this summary by Charles F. Dalziel