Re: Safety gap issues

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: "Malcolm Watts" <m.j.watts@xxxxxxxxxxxx>

On 25 Nov 2005, at 17:24, Tesla list wrote:

> Original poster: "JT Bowles" <jasotb@xxxxxxxxxxx>
>
> You said:
> "The breakdown for air is approximately 30KV per cm.  This is a local
> field strength and if the field is uniform (constant) then you can
> measure the distance to find the total breakdown.  The 25KV per inch
> you found probably assumes a geometry and applies to a short range of
> distances. "
>
> Well holy crap, that throws ALL my measurements with high voltage off
> a lot. My sparkgap for example is set at 7.5 to 8 mm. That means my
> sparkgap is set at 22.5kV? NO WAY; MY TRANSFORMER OUTPUTS 12KV ONLY.
> SO, IF IT WERE SET AT 22.5 KV, IT WOULDNT FIRE WORTH CRAP.

12kV is the open circuit RMS output voltage. The *peak* open circuit
output voltage is about 17kV. That is the regime most coilers operate
under. And if they feel really lucky, they open the gap up beyond
that too.

Malcolm

> THIS MEANS THE FORMULA:  1cm=30KV   cannot be correct
>
> Thanks a ton for the help, but I THINK you're wrong buddy
>
>
>
> >From: "Tesla list" <tesla@xxxxxxxxxx>
> >To: tesla@xxxxxxxxxx
> >Subject: Re: Safety gap issues
> >Date: Fri, 25 Nov 2005 08:00:02 -0700
> >
> >Original poster: "Gerry  Reynolds" <gerryreynolds@xxxxxxxxxxxxx>
> >
> >Hi JT,
> >
> >>Original poster: "JT Bowles" <jasotb@xxxxxxxxxxx>
> >>
> >>Use a counterpoise? You mean putting large amounts of al foil,
> >>spread on the ground, as an RF ground? WTF no way dude, that ruins
> >>the aesthetics of my coil.
> >
> >Counterpoise was for indoor operation.  If you are outdoors and have
> >a rod in the ground, GREAT.  Keep the NST with the coil and ground
> >the NST, secondary base, and strike rail to a common point and run a
> >heavy short wire between this common point and the pipe in the ground
> >(RF ground). Your target for sparks should be grounded to RF ground
> >at the common point (not the pipe end).  This keeps strike return
> >current out of the heavy wire to the pipe and will help keep RF
> >ground noise to a minimum.   Ground your variac and line filter to
> >mains ground.
> >
> >The breakdown for air is approximately 30KV per cm.  This is a local
> >field strength and if the field is uniform (constant) then you can
> >measure the distance to find the total breakdown.  The 25KV per inch
> >you found probably assumes a geometry and applies to a short range of
> >distances.
> >
> >Gerry R.
> >
> >
> >>i DO have a 4 foot Cu pipe driven into the ground, and 15 feet of
> >>wire is attatched to it. *I use this separate ground as a ground for
> >>the sparks to jump to.(from toroid directly to this)
> >>
> >>*I have read all over, 1 inch requires around 25,000 volts to make a
> >>spark connect. So, i have been measuring EVERYTHING using this
> >>equation. IN OTHERWORDS, I USE 1MM=1000V. My sparkgap is set at 7.5
> >>to 8 mm, thus 7.5 to 8 kV
> >>
> >>* my output is 15.5 inches- so i times that by 25,000 volts per
> >>inch- to achievmsnip...