BIG SNIPPP.... ( making terry happy) HI Ed... I used a single gap set ( tungsten 1/8" rods) with air forced cooling on my 14.4KV 10KVA piggie ... the heat involved is quite a bit it will melt/reduce/pit/blacken the tungsten rods to nubby little studs ;) also i found out i get better results if the air flowing thru the spark gap is at higher than atmospherical pressure blow dont suck Scot D