Re: Cable question (spark plug wire)

From: 	Jim Lux[SMTP:jimlux-at-earthlink-dot-net]
Sent: 	Friday, January 02, 1998 11:58 PM
To: 	Tesla List
Subject: 	Re: Cable question (spark plug wire)

> > >      4.  Get spark plug wire, from an auto parts store.
> > 
> > Spark Plug Wire is a misleading term.
> > 
> > More often than not, spark plug wires have no wire in them, but a
> > fiber sort of conductor.  Also, the additional resistance used to
> > suppress RF may be more resistance than you might want to put into your
> > system.
> > 
> Exactly. What you must find is what is referred to as "Solid-Core"
> plug wire. Normally, the only place you can find this is in "performance"
> auto stores. Most people want the noise suppresion of resistor core
> plug wires, but speed freaks don't :)

Indeed. It runs about $2/ft at Super Shops in Southern California.
Unfortunately, it also doesn't have any specs about breakdown voltage, etc.

A popular HV cable is RG-213 or RG-8. AWG 13 center conductor, good for 50
kV DC if not mishandled. Keep the shield grounded. It makes the field more
even, which reduces corona and breakdown, as well as making it safer. The
only problem is lack of flexibility. Spark plug wire is very flexible, and
has hi temp insulation (typ. silicone) to boot.

Various surplus suppliers have HV cable in small quantities, e.g. C&H sales
in Pasadena CA used to have 10 ga, 25 kV wire.

The commercial HV cable is designed to have a semiconducting layer around
the center to reduce corona effects. See Caton's web site for more info..
http://www.caton-dot-com. Same type of products available from Belden and
Rowe-Talley. The stuff is also available from Newark Electronics, although
as I recall, 100 or 250 foot minimum order. Samples might be available from
mfrs, if you ask nice.

RG-58 works for neon sign voltages (e.g. 7.5 kVAC RMS to ground).