Re: Capacitor Safety Discharge Method (fwd)

["Tesla list" <tesla@xxxxxxxxxx>]

---------- Forwarded message ----------
Date: Wed, 08 Aug 2007 21:59:44 -0700
From: Jim Lux <jimlux@xxxxxxxxxxxxx>
To: Tesla list <tesla@xxxxxxxxxx>, tesla@xxxxxxxxxx
Subject: Re: Capacitor Safety Discharge Method (fwd)

At 12:26 PM 8/8/2007, Tesla list wrote:

>---------- Forwarded message ----------
>Date: Wed, 8 Aug 2007 12:12:24 -0700
>From: Ray von Postel <vonpostel@xxxxxxxxxxx>
>To: Tesla list <tesla@xxxxxxxxxx>
>Subject: Re: Capacitor Safety Discharge Method (fwd)
>
>Jim:
>Sorry, your logic still escapes me.  How fast is the capacitor
>discharged if a resistor is open?   Yes, as you point out "There is a
>world of difference....", but what has that to do with safety?  I do
>not accept that there is any safe level of voltage when it comes to
>safety.  Perhaps you would care to state what voltage level is safe
>under all conditions but I don't.

The idea is that you discharge the bulk of the energy from the 
capacitor at a reasonable rate (without loud bangs and flashes.. say, 
at a few tens of amps), then, connect up your grounding hooks for safety.

As has been pointed out elsewhere, dropping a bolted short across a 
cap with substantial energy damages the capacitor, and probably 
causes damage to the cap terminals, not to mention the whole 
psychological thing of bringing the rod closer and closer without 
knowing exactly when it will go bang.

As far as safety goes, the electrical code says 50 volts in some 
number of secconds.





>The bottom line is that resistors are fallible just as are O rings.
>Don't trust your life to them nor advocate something that could and has
>killed some one.

of course not.  there's two things going on here:
a) discharging the energy in the capacitors (what the resistor is for)
b) ensuring safety and no rebound charge.. (what the grounding hook is for)

And, of course, you need multiple ground hooks, especially if you 
have multiple caps in series.