We describe elsewhere how microshocks can arise when a person touches an object in an electric field. We also give quantitative information on the sizes of voltages, charges etc involved. Here, we give information on how big they have to be for people to perceive them or to regard them as annoying.
These data come from tests in America. They took a sample of 136 adults, standing upright in an electric field such as you might find under a power line, and asked them to say when the microshocks were first noticeable ("perception") and when they became annoying. They did this when the microshock arose by touching a grounded object ("finger") or by discharging the person through a contact to their ankle (you might get this when brushing through long grass wearing sandals or with bare legs). The results are shown in this graph:
This shows, for example, that in a field of 5 kV/m, most people - over 80% - will perceive a microshock when they touch a grounded object, but only about a quarter will describe it as annoying.
Note: we have recreated this graph from a printed version so it may have lost some accuracy in the process.
