# Re: safety gap size

```Original poster: "Jim Lux by way of Terry Fritz <teslalist-at-qwest-dot-net>" <jimlux-at-earthlink-dot-net>

The problem is that everyone uses a different kind of electrode for the
safety gap.  If you use sphere electrodes, then you could just use the
spherical gap tables (linear interpolation will work well enough) and set

If you use some other kind of gap, then the easiest approach is empirical..
open it up til it just doesn't fire without the LC connected.

For a starting point, you can use the uniform field breakdown distance,
which is sort of a worst case (i.e. your gap will always breakdown at a
lower voltage, so it's "safe").. 30 kV/cm or 70 kv/inch are nice starting
points. For a table...

Vrms Vpeak cm     inch
6      8.4     0.28     0.12
9    12.6     0.42     0.18
12    16.8   0.56     0.24
15     21     0.7       0.3

----- Original Message -----
From: "Tesla list" <tesla-at-pupman-dot-com>
To: <tesla-at-pupman-dot-com>
Sent: Friday, March 28, 2003 4:36 PM
Subject: RE: safety gap size

> Original poster: "Christopher \"CajunCoiler\" Mayeux by way of Terry Fritz
<teslalist-at-qwest-dot-net>" <cajuncoiler-at-cox-dot-net>
>
>
> I figured it was something like that, however, I was hoping that
> somewhere along the way, someone might have experimented with a
> variety of NST's, and did the math... no sense in re-inventing
> the wheel, aay? 8-)
>
> As an alternative, perhaps all who currently have functioning
> coils could take a measurement, and we could form a collective
> of the data (voltage,gap_size), and derive a reasonably accurate
> formula from that data that we, and future generations of coilers
> could benefit from for centuries to come.
>
> Imagine... SafetyGap_mm = Nst_E * X
>
> Who will be the first to find "X" ???
> ---
> Christopher 'CajunCoiler' Mayeux
> http://www.cajuncoiler.tk
>
>  > With nothing else connected to the NST output but the filter, the NST
>  > voltage will be the normal output voltage.  Set the gaps so they just
do
>  > not fire with just the filter connected to the NST.  Then the gap
voltage
>  > will be just a little higher than the NST normal rated voltage.
>
>

```