Re: Lightning and computer?
- From: w_tom <w_tom1@xxxxxxxxxxx>
- Date: Fri, 22 Apr 2005 19:22:21 -0400
Your house is earth grounded adjacent to the circuit breaker
box. Does every incoming utility wire make a 'less than 10
foot' connection to that earth ground? Or is the AC neutral
wire only earthed. The former is required for appliance
protection. The latter - only one wire earthed - is what most
homeowners have, which is why they suffer electronic damage.
That earth ground rod means nothing about earthing the
third prong on a wall receptacle (see a response to Al Dykes
quoting Telebyte's Reference Manual). Meanwhile numbers
demonstrating why a wall receptacle is not earth ground were
posted previously. That 'earthed' receptacle ground prong
leaves UPS and adjacent appliances at up to 12,000 volts.
Why? Wire is too long. Too much impedance. Sharp bends and
slices in that wire. Ground wire bundled with other wires to
even created induced transients. So many reasons why a plug-in
protector has no effective earth ground.
With an earth ground rod adjacent to the AC electric box,
then your 1972 house may meet post 1990 standards. Every
incoming utility wire must connect to that ground rod. Two AC
electric wires bypass that earthing to distribute destructive
transients everywhere inside the building. Do you think a
plug-in UPS will stop or absorb it? Even the UPS manufacturer
does not make that claim as made obvious in those UPS specs
not yet provided?
Meantime, my real experience tempered by both fundamental
theory (ie wire impedance) and design experience says, first,
the appliance internal protection saved those appliances.
Second, the phone line 'whole house' protector - and not the
UPS - provided protection. Third, some appliances could have
acted as a surge protector to protect that UPS.
I have even traced damage through a network of computers
where two plug-in protectors simply connected a direct
lightning strike into the network via adjacent computers, and
eventually (and destructively) to earth ground via modem and
phone line. Two adjacent appliances - a TV and VCR. One was
damaged. The other was not. Understandable once we looked at
how both were connected to earth.
Without analysis at the electronic component level, one
cannot say how something was damaged or why something was not
damaged. Others will even read a tabloid newspaper, see a
trend, and also know exactly what happened. Instead, the
devil is in the electronic details. Analysis as to why damage
does and does not happen must be that detailed. One cannot
just know from a list of what was damaged. Even in that
network, adjacent protectors at one computer caused modem
damage on another (networked) computer in another room.
Your experience means nothing without both fundamental
theory (which you disparage) and without knowledge at the
electronic component level (IC, inductor, resistor, etc).
Instead you just know because this was damaged and that was
not? Invalid reasoning made even worse numbers are ignored.
You ignore wire impedance; instead posting in terms of wire
resistance. This is exactly what a plug-in protector
manufacturer hopes the naive will do to promote their
undersized and overpriced product.
But show me. Where is that manufacturer spec that claims a
UPS protected anything? Where are the joules ratings for that
product? Where are any numbers that support your
speculations? Experience without basic electrical knowledge -
without the underlying theory - makes one his own worse enemy.
At best, you have first hand speculation. Protection exists
inside appliances. You did not even know about the protector
installed free by the telco. Somehow a wall receptacle
connected by 120 ohms wire impedance is still earthed? Using
your speculation, a UPS connected to the motherboard ground
would also be earthed. But then if the motherboard is already
earthed, why do we need a UPS for protection?
First, all appliances have internal protection. Some
devices have better protection than others. Plug-in
protectors profit on this. They put a grossly undersized
protector next to your appliance. A transient too small to
overwhelm internal appliance protection, instead, destroys the
grossly undersized protector. Then the famous proclamation.
"My protector sacrificed itself to protect the electronics".
Wrong. The protector did nothing. Why was the appliance
protected? Again, all appliances already have internal
protection. A transient too small to damage the appliance did
destroy the grossly undersized protector.
Second, some appliances make a better connection to earth
than others. Even the adjacent TV and VCR. Only the VCR was
damaged because it made a better earthing connection.
Transient found earth, destructively, via the VCR.
Why were those networked computers damaged while on power
strip protectors? A shorter path to earth ground was from
protector, through adjacent computer and eventually to earth
via phone line 'whole house' protector. Why was the TV not
damaged that had no plug-in protector? Define the destructive
paths to earth?
Third, it gets even more interesting. One house at the end
of a cul-de-sac had far more damage. Why? It was closer to a
buried long distance pipeline - geological differences. Some
buildings suffer more damage because they are connected to a
last transformer on the street. Again, why are some things
damaged and others intact? First, at the electronics and
geological levels, what are the preferred paths to earth
ground for a destructive transient? Without those specific
details, then one can only wildly speculate.
Fourth, look at manufacturer's specs for that UPS. It does
not even claim to provide protection. To work at the
appliance, a plug-in protector must stop, block, or absorb
transients. Why does the telephone switching computer work
through every thunderstorm and suffer no damage? Effective
protection means properly earthed 'whole house' type
protectors be located 50 meters (150 feet) away from
electronics. Then protection inside that switching computer
will not be overwhelmed.
I cannot say specifically what did or did not cause damage
to each appliance. Insufficient detail is provided such as
where all connections to earth ground exist, length of wires,
sharp bends and splices in each wire, what wire is bundled
with other wires, what wire is draped on other conductors such
as baseboard heat, where each house is located geologically,
how the cable TV wire (not even connected to the computer)
enters the building, and other contributing factors such as
rebar mesh in the concrete floor of some houses. But we know
from both experiences and proven concepts even before WWII; a
plug-in protector is not effective. Residential protection
begins with a 'less than 10 foot' connection to the same
(single point) earth ground - for every incoming utility.
How are your neighbor's utilities earthed? To the same
earth ground rod? Do utilities enter at different sides of
the building? The number of questions that need be answered
are hundreds before we can even begin to speculate why things
are and are not damaged.
What does a transient do when it gets to a UPS not in
battery backup mode? Goes right through the UPS. A UPS not
in battery backup mode connects computer directly to AC
mains. Where then is the protection? And again, where are
manufacturer's specs that define that protection for each type
of transient? Where are the joules number? More details
necessary to explain why some things are damaged whereas
others are not.
The analysis must include everything in a path from cloud to
earth, and then from that earthing point to electrical charges
some miles distant. That's right. In what direction did this
earthed transient leave the building?
Leythos wrote:
> Like it or not, my house has an earth ground just outside the main
> breaker panel, it's that nice copper rod driven into the ground and
> then connected to the nice earth ground bus in the panel - that
> means anything connected to the third prong in the properly wired
> outlets has a connection to Earth ground.
>
> Now, you assert that my house is not meeting 1990 standards, and it
> may well not meet them according to the NEC, but, as my REAL
> EXPERIENCE indicates that the UPS's connected to my servers and
> workstations (and other electronics) have save them from damage when
> those around me that are not using them have damaged devices, how
> are you going to explain that?
>
> This above is the part you should be addressing - while you claim
> that they have no benefit, it appears, to many people, in the real
> world, that they do. In my case, I have direct, first hand,
> experience that proves to me that you are wrong when it comes to
> your incessant ranting about UPS's not being able to protect devices.
>
> Please explain how my USP's have NOT protected my devices yet they
> remain undamaged while devices around me that don't have UPS's
> are damaged.
.
- References:
- Lightning and computer?
- From: Susan
- Re: Lightning and computer?
- From: w_tom
- Re: Lightning and computer?
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- Re: Lightning and computer?
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