Re: Tubing for high voltage wire

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

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


----- > <SNIP>
 >  >
 >  >Also, are there any readily available kinds of tubing that have a high
 >  >dielectric rating to make HV wire with?  I haven't found a listing for
 >  >clear vinyl tubing's puncture voltage yet. If anyone knows this please
 >  >tell me.
 >  >
 >
 > I don't have any specs, but I can tell you from personal experience that
 > the clear tubing used with oxygen masks in hospitals withstands my 14.4
 > KV pig power with no punctures!  Make friends with a nurse or doctor and
 > you'll have a ready supply, as they are only used once then tossed out.
 > I use teflon insulated # 16 wire pulled through the tubing for all of
 > my high voltage leads, save for the high current ones in the primary.
 >
Interesting.. so, you actually have two layers of insulation. The first
being teflon (generically, PTFE) in close contact with the conductor which
is roughly 0.05 inches in diameter.

How do you know there are no punctures?  I've been involved in testing a
variety of insulated wire for 18-20 kV over the past year, and it's pretty
subtle when it starts to fail. For example, a piece of 30 kV rated wire was
immersed in a conductive liquid (impure water) and run at 20 kV DC for a
number of hours.  We watched for two things: 1) partial discharge and 2)
increase in leakage current, both of which inevitably occurred after 36-48
hours or so.  We also did tests with the wire laying on a metal plate.  In
all these, you couldn't see the pinholes developing, although in an
egregious case, you could see the corona in the dark.