record sparks then nothing

Hi All,
	Tried a bit of tuning on my coil today and got regular 36" sparks to a
grounded rod. Great I thought then I decided to move the coil slightly as I
was getting too close to the wall. Wound up the variac again and it ran for
a few seconds then tripped the mains. Darn I thought. When I looked at the
coil I noticed that the ground lead had become disconnected,so i had been
running without a ground for a few seconds at least. I dismantled the
system and got the megger out. It seems that I have got an ground fault on
one of the primarys of one of the trannys They are GE 10 kV 50mA they look
quite old but hopefully they are tar filled rather than resin filled.
anybody ever dismantled one of these? Oh well looks like it is back to the
9 Kv 50 f.a.r.t. again for the teslathon unless I get time to sort out my
radar transformer. That will teach me to be to be too keen to squeeze the
last bit of spark out!!

bob golding