Let-go currents and voltages

Let-go current curves are presented for commercial 60-cycle a-c and for direct current. New data are presented which confirm previously published let-go current curves for direct currents having various amounts of a-c ripple content, together with new data for 60-cycle a-c let-go voltages. The voltage analysis is extended to cover direct current, thus rounding out the subject of let-go hazards. Reasonably safe let-go currents and voltages are computed from tests made on substantial numbers of normal, healthy individuals. It is believed that reasonably safe limits may be based on the predicted response for 99 1/2 per cent of a large group. The probability of receiving dangerous electric shocks must be anticipated, and preventive measures must be considered vital ingredients in the design of machines, in the framing of operating instructions, and in work procedures.