High voltage wire

From:  Jim Lux [SMTP:jimlux-at-earthlink-dot-net]
Sent:  Friday, April 03, 1998 1:13 PM
To:  Tesla List
Subject:  Re: High voltage wire

Tesla List wrote:
> ----------
> From:  Bill the arcstarter [SMTP:arcstarter-at-hotmail-dot-com]
> Sent:  Thursday, April 02, 1998 1:15 PM
> To:  tesla-at-pupman-dot-com
> Subject:  Re: High voltage wire
> It was written:
> >>Cheap source for high voltage wire?
> >>
> >Regular wire with some non-metalic rubber air hose around it.
> Careful here!  I recently tried using some automobile vacuum hose for
> this and here's what happened:
> Measured insulation resistance on the outside of the tubing at points
> about one inch apart:  Read >20 Megohm
> Inserted a piece of #10 copper wire into either end of a three inch
> length of the same type of hose.  Measured the resistance from end to
> end:  Read 300 ohms.  More than enough conductance to light an LED off a
> 9v battery, much less act as a better conductor than nonconductor for HV
> applications!In fact, it has been used as a HV resistor. You could even run air down the middle for cooling...

> This stuff was completely unsuitable for the purpose which I had
> intended.  Of course I didn't discover that until I had incorporated
> about twenty small pieces of the stuff into the HV device...
> You might be OK using clear vinyl tubing for a HV insulator...

I use polyethylene air tubing. It is a bit stiffer, much cheaper than vinyl, and I think the breakdown 
voltage is higher. It is available in various wall thicknesses (as is vinyl (Tygon, e.g.)). For instance, 
the .25 ID is .375 OD, so the wall is .0625, or good for 30 KV or so...