Re: Pole pig HV wires (fwd)

---------- Forwarded message ----------
Date: Tue, 05 May 1998 23:48:47 +0300
From: Harri Suomalainen <haba-at-cc.hut.fi>
To: tesla-at-pupman-dot-com
Subject: Re: Pole pig HV wires (fwd)

>From: Chip Atkinson <chip-at-pupman-dot-com>
>I am looking to get some new wires to connect from the HV of my pole pig
>to the tank circuit of my coil.  I'd like to have something with enough
>insulation that I could let the wire lay on the concrete, touch each
>other, etc., and be heavy enough gauge to carry the current, say up to 1A
>for sake of upgradability.  Will neon sign wire be enough?  

>I believe that
>it's just the current (amps) that determines the necessary wire gauge,

Well, almost correct. Proper conductor size will result in low enough
resistance that the wire will handle the current without overheating.

However, with HV stuff the wire dimentions will also have sometimes
other effects too. Thin wire will have tight curve at edge. Curving and
wire size *will* effect the electrical field in the insulator. Very thin
would be much like a sharp edge which would result perhaps in problems.
That would lead to improper electrical field and partial discharges which
would grow end eventually result in total breakdown of insulator.

For the sake of safety I'd prefer cables with grounded shields. Especially
with conducting floors (like concrete). Pole pigs also have pretty high
power levels which would make me much more cautious. Unfortunately
neon wires (at least over here) are *not* made with grounded shields.
I'd not use them.

Why not just use some pretty common large size coaxial cables? They
do have shields you can ground. They are available easily. Probably some
mechanical protection with plastic tubes would be a good idea.

Proper grounding is very important here. I've seen coaxials grounded
to separate ground (rf ground at some distance) while the concrete floor
was at electical network ground. Due to capasitive coupling the coaxial
cables proved to be hot at rf-grounded outer shield. They had a  nice glow
discharge to the concrete floor.  This is just another example of how
important proper grounding is!

Harri Suomalainen     mailto:haba-at-cc.hut.fi

We have phone numbers, why'd we need IP-numbers? - a person in a bus