In message , Andrew Gabriel
writes
In article ,
geoff writes:
In message , The Natural Philosopher
writes
Dave Liquorice wrote:
On Sun, 7 Jun 2009 09:46:46 +0100, PeterC wrote:

I wondere if the line was DC, but when he stood up he was close to
the
line and then he had to touch it so...
Others have mentioned DC or AC at 25kV. How far will 25Kv jump in
dry air? Note jump not sustain an arc once it has started. The
sound is of two bangs. Other arcs that I've seen on youtube etc on AC
systems have a definate buzz sound. Of course the explosive
vaporisation of body fluids will make quite a bang and could mask
any AC buzz.


25kv will just about jump a spark plug gap/.

What, just about ?

I always thought the rule of thumb was 30kV / cm

In the physics lab, we used to have a rule of thumb that
25kV could just about arc across a cm, but needed an inch
for insulation. Shape of electrodes makes a huge difference,
and things like humidity make a bit of difference.

spark plug gaps are what, 20 thou? 0.5mm

Yes, but they operate at high pressure.

Not my choice of example ...

--
geoff