"Franc Zabkar" wrote in message
...
On Mon, 8 Sep 2003 17:28:57 +1000, "Richard Freeman"
put finger to keyboard and composed:

Damn just when I thought w_tom had grasped the concept. Once again w_tom
goes on with his fantasy that Lightning comes in via AC mains and exits
via
the phone Line.

I was skeptical, too, until I saw it for myself. See this post:


http://groups.google.com/groups?selm...goblue.net. a
u&output=gplain



Firstly where is this earth on the Telephone line ????? - It does not exist.
some (in Australia very few) phone lines have surge arrestors but these are
not generally implemented as they have proven to be ineffective in the case
of near/Direct strikes.

going through your list :

Firstly, my friend's neighbour lost his electrical distribution box,
so this confirms that the strike came in on the mains.

Well Maybe and I have not said it never comes in via Mains just that if it
does it is so uncommon that I have not seen it.
Reading through the list of damage however suggests that your friend
suffered a direct strike in which case :

A) all bets are off
B) a Lightning strike that has blown the ****e out of a switchboard is
barely going to flinch at blowing the ****e out of a MOV
C) Equally likely and the more probable scenario is that your friends house
was hit and the Lightning followed the path to the best Earth available -
that of the MEN Mains

Failure of PCtel DAA module (plug-in type for PCChips M585LMR
motherboard). Symptom was "NO DIALTONE". Parallel telephone was
undamaged. Both phone cables were plugged into a "protected" power
board.

Plug in module connected to the phone line - still matches the scenario that
the strike came in via Phone and exited via Mains
The parallel phone most likely rode out the strike. In fact this sounds like
a module in a PC if the strike came in via the Mains and exited via the
phone line why wasnt the PSU fried ? the more likely scenario is that the
strike came in via the phone line and headed for the chassis earth on the
PC.

(2) Portable telephone base station - shorted 15V zener diode at tip
and ring inputs.

Powered phone connected to the phone line - still matches the scenario that
the strike came in via Phone and exited via Mains

(3) Television - shorted rectifier diode, blown fuse, and failures in
the +5V regulator, remote sensor, and microcontroller.

(4) Two VCRs - CPU and power supply failures.

Nasty sounds like a direct strike which also entered via the TV aerial and
headed for the earth provided via the double insulated mains - note no phone
line involved here

(5) Audio unit - CPU failure, P/S OK.

Dont know what this was but if double insulated equipment connected to the
VCR/TV then Lightning was probably still travelling in via the TV aerial and
had not dissipated completely via the VCR or TV Again no phone line
connected here

(6) Security light - faulty power controller, light dims but won't
turn off.

Sounds like a direct strike The Light being installed outdoors probably
copped a secondary strike not the full Strike - you would have found that
one of w_toms surge busters would not have saved this anyway. Also no phone
line involved here

(7) TV - blown fuse, damage to P/S

entered via the TV aerial headed for the AC mains again no phone line
involved here

Well sounds like your Lightning still mostly obeyed the laws of Physics and
entered by unearthed / poorly earthed paths and headed straight for the best
earth available that of the AC Mains. as an addendum the mains in this
instance probably rode out the strike to a certain degree but in all the
cases a path for the lightning to have entered by other than AC mains
exsists.
Lightning aint Rocket science it obeys the laws of physics - it is just with
high energy events such as lightning different laws of physics often come in
to play.
Lightning seeks a path to the best earth it can find and note here that a
single earth stake buried in the ground is more often than not hardly the
best earth available the MEN system however used for 240/415V mains
distribution however frequently offers a superior earth for Lightning
strikes

Regards
Richard Freeman