Tesla List wrote: > The dielectric strength of air is 20k(!!)V per mm not 20v/mil. 30 kV/cm, or 3 kV/mm, or 76 kV/inch, or 76 V/mil, is a better figure. But I read somewhere that less voltage than about 240 V (or something in this range) cannot cause air breakdown, no matter what is the distance. (Does someone know more about this?) Antonio Carlos M. de Queiroz