"Martin Whybrow" wrote in message
...
If your set-up reaches a high enough field strength to ionise the air, the
current will almost certainly flow through the wood, it's not a good
insulator.

Eh? Wood was being used for an insulator for voltages well above this, well
before you were born! It won't be bothered by 80V.
The ionization comes from concentrating the field between the screws.

Add a capacitor because the transformers
have way too much resistance and inductance to get a healthy spark.

No, although healthier transformers is probably a good idea anyway. You
need an RC circuit because current kills the metal, and you get much higher
peak currents when you discharge a capacitor in microseconds than
continuously releasing the same energy (which BTW won't work for EDM...
you'll be arcwelding instead .

Tim

--
"That's for the courts to decide." - Homer Simpson
Website @ http://webpages.charter.net/dawill/tmoranwms