Variac arcing = kickback? (fwd)

---------- Forwarded message ----------
Date: Wed, 14 Jan 98 21:46:42 -0500
From: Adam <absmith-at-tiac-dot-net>
To: tesla list <tesla-at-pupman-dot-com>
Subject: Variac arcing = kickback?

I decided to see what would happen if I added more transformer power to 
my project, and I got disturbing arcing in the variac.  The variac is an 
18 general radio 120V variac, which was feeding the two 9kV 60mA 
transformers on my project without incident.  There is 8 feet of 14-3 
cable between the variac and the project, and the ground wire in this 
bundle is unused.

When I added transformer number three and fired up the coil, I got power 
arcs between the variac's moving brush assembly and variac housing above 
it.  The arc is jumping about 3/16" so I'm pretty sure it's not just the 
normal 140V there!  What ever is sparking across this gap is followed by 
a power arc from the mains, which melted a bit from both parts of the 
variac.  Somethings seems to be kicking back from the neons.  This only 
seems to happen when there is a breakout from the toroid.  I am naturally 
concerned for all appliances in the house, and I would like to correct 
this problem ASAP.

What's going on here?