Insulation Problems.

["Aleks Nowak" <Aleks-at-sn2.co.uk> (by way of Terry Fritz <twftesla-at-uswest-dot-net>)]

Hi,
 
I would like to pose a question regarding how to insulate sufficiently the
centre HV terminal from the two primary terminals on a car ignition coil.
My situation is as follows:
 I have wired from the mains via a 400W dimmer and a 3uF motor start cap in
series on the "positive side" (although with AC is shouldn't really matter)
a car ignition coil. It worked fine - nothing over heats, and the things
arcs like heck alternating between the two primary terminals as one would
expect. 
My problem has been this: 
How to prevent the HV terminal in the centre from arcing over to the two
primary terminals. I have already got HV wire connected, but i can only
draw an arc that is smaller than the distance across the terminals on the
ignition coil. I have tried to insulate the two primary terminals the best
I can with firstly self amalgamating tape, then a thick coat of hot glue.
The problems occur after I draw an arc of about 3cm, the insulation breaks
down, an the ignition coil begins to arc to itself again.
Any thoughts on this matter would be greatly appreciated.
 
Thanks  in advance,
 
Aleks Nowak