A Study of the Hazards of Impulse Currents [includes discussion]

Correlation of research from scientific laboratories in Europe and America, together with accident records obtained from several nations, permits tentative criteria for the hazard from short shocks and impulse discharges. The hazard from short shocks, those obtainable from both power frequency circuits and apparatus capable of producing impulses, is believed primarily to exist because of the energy contained in the discharge; the crest of the initial current, quantity in the pulse, and shock duration being related quantities of secondary importance. Formulas for reducing the electric shock hazard to the proposed criteria for safety are derived for both surge discharges and impulses of an oscillatory nature. Applications of the formulas are illustrated with examples. It is anticipated that this study may be of value in establishing the hazard from industrial equipment capable of producing impulses, or in reducing the hazard; in evaluating the effectiveness of lightning grounds; and in other similar applications.