A Method for the Exposure of Miniature Swine to Vertical 60 Hz Electric Fields

A Plexiglas enclosure was built to hold Hanford miniature swine for exposure to vertical 60 Hz, single-phase electric fields; water was provided through a grounded metal drinking nozzle. The field at the top of a pig's back was increased over the field in the empty enclosure by a factor of 7. A pig's impedance to ground, while standing on a grounded metal plate, was about 2-3 kohms. The average normalized short circuit current for four swine was 6.8 μA/(kV/m). All of the swine were able to drink with no evidence of shocks at the maximum attainable unperturbed field strength of 55 kV/m. The current between the grounded nozzle and the drinking pig was 1-3 μA/(kV/m). The threshold of perception of a mouth-to-nozzle current averaged 275 AA. Two swine exhibited ear flicking above 50 k/m, and visible hair motion was observed on the ear of one anesthetized pig at fields larger than 40 kV/m. A behavioral test suggested that swine were able to perceive fields greater than 30 kV/m. Photographic tests detected no corona discharge from an anesthetized pig or the test enclosure.