Re: Spark Shield

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

Original poster: Terry Fritz <teslalist-at-twfpowerelectronics-dot-com>

Hi Greg,

A "shield" for spark is not so easy.  Tesla had to put up grounded wires on 
his roof to keep from burning the Colorado Springs lab down.  The wire 
attracts the arcs and safely grounds the current away, much like a 
lightning rod.

About the only way I know of making something that will hold off +300kV 
sparks is to use many many layers (like 50) of poly plastic sheeting like 
is sold for paint covers.  The many layers will add up to hold off the 
extreme voltages at high frequency.  However, there is still a danger of 
setting the mess on fire which would probably be pretty bad.

The arcs are attracted to anything the has a dielectric constant higher 
than air, which is just about everything.  Nothing will tend to "repel" the 
arcs.  Tesla coil arcs will happily blow right through plate glass and 
such.  Perhaps heavy thick plastic...  Beware Lexan since it burns like 
gasoline once it gets started.  So some thick (1/2 inch) not very flammable 
plastic with a low dielectric constant...

It might be easiest to try and lower the coil or find someplace with a 
higher ceiling.

Cheers,

         Terry


At 05:15 PM 11/21/2004, you wrote:
>Hi,
>
>I'm looking for suggestions on how to best shield the
>ceiling (unfinished) in my basement from sparks. A few
>posts I've seen indicate that a grounded chicken wire
>screen is quite effective. I'm thinking this would
>probably work, but wouldnt it have a tendency to
>attract the sparks?  I'd rather not encourage arcs to
>the ceiling, but prevent those that do occur from
>striking the air ducts, wiring, etc.
>
>Any comments or suggestions from those with experience
>in this area will be most appreciated.
>
>Regards,
>Greg