Dear Dick, spark gaps are a genuine way of measuring high voltages in a HV-Laboratory. There exist tables for DC and AC 50 Hz. Spark gaps must be used, as it is impossible to use a rotary swich in a
In interesting effect with spark gaps is the way that they change character when they are not used. Apparently the metal surfaces grow whiskers which are burned away with use. So if you do not use a
Hi Stwart, the same thing is used in surge arrestors for submarine cable repeaters....the high voltage clamp is a gas tube, but being in the dark it requires an little ionisation to be sure it strike