Re: Surge / Ground / Lightning

On Mon, 5 May 2008 09:28:05 -0700 (PDT), trader4@[EMAIL PROTECTED]
 wrote:

>On May 5, 10:54 am, "Dave" <no...@[EMAIL PROTECTED]
> wrote:
>> I wonder why, since electrical codes in North America
>> and Britain require a ground connection at each outlet;
>> computer power cords are 3 wire?
>>
>> (snip)
>>
>> hot neutral ground
>
>
>Meanwhile, I'm still waiting for an explanation from w_ about how
>surege protection inside that computer can work?   Where is that
>direct connection to earth ground, without which w_ says surge
>protection is impossible?   Does the computer have a mythical earth
>ground inside?  The answer is it doesn't.  It is acting under exactly
>the same limitations and uses the same components, typically MOVs to
>do what a plug-in surge supressor does.  w-'s answer to this is to
>claim that electronics, appliances, etc do not use MOVs, a claim
>previously smashed, because of course they do.    Plus it really has
>nothing much to do with the question anyway, because the computer,
>appliance, etc still HAS NO DIRECT EARTH GROUND, without which w- says
>protection is impossible.

I'm curous to know how surge suppression can work without a ground
(earth) of any sort. Does the "black box" detect overvoltage and
disconnect the power like an earth leakage safety switch?

This might be fine for a TV, but surely not for a computer. 

I don't recall any computer I've owned that did not have a three wire
connection to the mains. That and a MOV is OK for smallish surges, but
I believe that for a large surge, the sort that will blow a telephone
off the wall, one needs a large, short-path earth for the surge
detector to dump the extra power down.

I've got a few plug in protectors here and there to sop up a small
spike, but when a storm is within a few km, I pull the phone wire out
of the ADSL router, and the plug out of the mains. If I'm working at
the time, I might just keep a watch on the weather radar and count
lightning fashes to thunder times. It's rare that I get interrupted. I
have underground power and phone lines so that gives a little extra
protection, I believe. I've been told that Australian phone lines are
the most vulnerable, and the most urgent to protect or disconnect.
I hope to be going wireless soon which obviates this problem.

jack