breakout voltage

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Luke" <Bluu-at-cox-dot-net> 

I found the following formula on the web.

The formula for the field strength on a conductor with a given radius is:
Field strength = Voltage / Radius.
The break down voltage for air is approximately 76KV / inch.
This value varies with humidity, frequency, temperature, barometric 
pressure etc.
So combining these gives:
Max Voltage (before air breakdown) = 76KV * Radius (in inches)

Is this correct for a close approximation?
When applying this to a toroid I was assuming the minor radius should be 
considered since it is the smallest curve on the toroid so the field 
strength would be strongest there.
Am I correct in assuming this formula could be applied to the minor radius 
of a toroid to get it's approximate break out voltage?


Luke Galyan
Bluu-at-cox-dot-net