RE: Discharging HV Caps

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

Original poster: "Lau, Gary by way of Terry Fritz <twftesla-at-qwest-dot-net>" <Gary.Lau-at-compaq-dot-com>

>I would think the best way to manually discharge the cap would be by
using an 
>insulated stick of some kind and shorting the spark gap.

This sounds appealing in that no potentially-open resistors are needed.
But if the cap did contain a significant charge, it would ring up the
primary, then the secondary, and odds are that you'd be standing pretty
close to or touching the secondary, and....

If everything is hooked up, an NST or pig power supply will rapidly
discharge the cap as soon as power is turned off.  It's only when some
segment of the gap/primary/cap circuit goes open-circuit (like the
primary tap coming off) that this built-in mechanism fails.  Then
shorting the gap won't help either.

I believe the safest approach is to have a bleeder resistor permanently
installed across the cap.  It's easy to check with an Ohm meter
occasionally if you want to be sure it's still intact, and being
permanent, is less likely to be damaged through handling than something
mounted on the end of a pole and dropped on the floor.

And if your cap is comprised of several in series, then each cap needs
its own bleeder.

Gary Lau
MA, USA