Human response to pulsed electric fields in sea-water

The accepted 50/60 Hz current, human electro-physiological threshold responses of feeling, let-go, difficult breathing, fibrillation & convulsions are reviewed, Similar response thresholds are required for the safe design of electrical shark repellents where the relevant parameter measured in sea-water is volt per metre. An experiment is described which hypothesizes a simple proportional relationship between the two sets of electrical conditions. This involves the use of a single test subject as a “transfer standard” between the two. The transfer coefficient was determined at the threshold of feeling and used to predict where the let-go threshold field strength in sea-water should lie. The equivalent ‘let-go’ threshold case was determined. This estimate confirmed the predicted value. The same proportional relationship is consequently applied to indicate the threshold field strength at which difficult breathing, fibrillation and convulsions may occur. Useful data on 50 Hz fields in sea-water is also derived.