High voltage leads from coax

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Original poster: "Arpit Thomas" <neko4-at-dodo-dot-com.au> 

Hi, I've read peoples advice as to use the centre conductor of a piece of 
coax cable as high voltage wire. I tried this for myself, first with a thin 
bit of rg58 coax from an old 10 base t networking setup. THe insulation was 
thin, transparent, but solid. The sheathing was pretty difficult to stip 
off, easier than mains cable but harder than rg6 coax. THese seemed to work 
fine with a 15kv 30ma psu, just as well as some mains rated cable i had 
lying around . Neithers insulation broke down at 15kv. Just then I tried 
rg6 coax. THis is the expensive stuff pay tv installers use. Stripping off 
the outer sheath was an absolute pleasure, it came off so easily. THen I 
saw the core's insulation was made of foam. Ohoh, I thought, I've read 
about this! But screw it, I used it anyways. I put 15 kv onto the end of a 
steel coathanger wire, and put it next to (point touching ) the side of the 
0v wire.  I could see a corona as I brought the coathanger near, and hear a 
bit of crackling. nothi!
ng happened besides that. I tried another spot. Nothing. Then another. 
BZZZZZZZZZZZZZZZZTTTTTTT it arced through setting the foam on fire. the arc 
strengthened the fire into a roaring little thing, and in a matter of 
seconds it was self sustaining. I then experienced a most interesting 
effect. the flaming insulation would melt and plop to the ground still 
burning, making a whhzzzztttt sound. Try this for yourself, careful though, 
the molten bits hurt!

So, conclusion - rg58 appears to have solid insulation, use this with care. 
rg6 coax seems to have foam insulation. when you can pull long bits of 
sheath off in one go, and your knife slices through the insulation like 
butter, you have foam. no go.
More wire tests to follow! Please don't take 15kv safety to be any 
indication of higher voltage suitability.  Also, you MUST overdesign the 
wires, as seen with the foam, they may not arc through straight away, 
however if one gets rubbed a bit, who knows what'll happen. THe fire 
intensified by electricity is an interesting demo, and soemthing which has 
been performed at my house many many times , usually to my annoyance :) 
have a go at it with an old neon sign transformer, you'll be impressed!
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