Per page 265 out of 15th edition ARRL Radio handbook, Figure 26. Usual breakdown ratings of common plate spacings air gap in inches/ peak voltage breakdown GAP Voltage .030 1,000 .050 2,000 .070 3,000 .100 4,000 .125 4,500 .150 5,200 .170 6,000 .200 7,500 .250 9,000 .350 11,000 .500 15,000 .700 20,000 |