Re: belkin power conditioner for my Samsung LCD - is it worth it???

On Sun, 19 Aug 2007 16:28:10 -0700 w_tom <w_tom1@xxxxxxx> wrote:

| The word "direct" must be understood in context. For example, a
| direct lightning strike to wires down the street (a direct electrical
| connection between cloud and that utility wire) is also a direct
| conneciton to household appliances. That current seeks earth ground.
| One good path may be via a household appliance by overwhelming
| protection already inside the appliance.

This is why I have to ask you what you mean by "direct" to be sure.


| Cable is connected directly to earth ground. A $2 ground block even
| sold in Lowes or any hardware store connects that cable shield to
| earth ground. But to make that connection direct (from lightning's
| perspective) means that wire must be short (less than 3 meters), no
| sharp bends, no splices, not inside metallic conduit, and separated
| from other ungrounding wires. IOW a wire must be more conductive so
| that a surge will not seek other destructive paths inside a building.
| Violating those other requirements means the connection is not so
| 'direct'. A cable grounded to a water faucet really is not a direct
| earthing connection - too much impedance - not a sufficiently
| conductive connection.

So it sounds like what you mean by "direct" is a straight and short
path. I would certainly agree with that. I was worried you meant a
"solid connection".


| Electrical nature of coax means its center conductor need not
| connect to earth. End of that wire (inside amps) further makes any
| voltage difference irrelevant. Earthed shield of a coax effectively
| means center conductor is also earthed - in most situations.

But this I will disagree with. The voltage difference between the
center conductor and the shield can be as high as, or intermittently
even higher than, the breakdown voltage of the insulation between the
center conductor and the shield. And in typical RG-6 it can be a few
thousand volts.

You feel ok about applying a few hundred volts to the first stage RF
ampifier in your new super big screen TV?

This is why we need to have a lightning/surge arrestor installed on
the cable line right at that point of best path to ground, with a
very low threshhold of voltage breakdown or arc-over so that we can
get any surge diverted from the center conductor to ground. The
breakdown voltage on this device can be set very low (compared to
similar protection on electrical power wires). It just needs to
have enough durability to sustain the current from at least one
direct strike. More would be better.


| Telephone wires cannot connect directly to earth. So we earth both
| wires via a 'whole house' protector installed free by the telco. But
| again, to be earthed means that 'less than 3 meter' connection.
| Earthing via an AC receptacle - is not earthing for obvious electrical
| reasons.

It's just the same thing, although the voltages are different and the
fact that neither wire is a "grounded conductor". Some device to divert
overvoltages to earth over the best path is needed. Protecting it at
the entrance for the whole house is the right way.

I do agree that earthing non-power wiring via the power ground wire is
not to be depended on. That's a bad path to ground (worse if there are
subpanels in the power wiring). But once there is such well grounded
whole house entrance protection, on both phone and cable (the shield of
coax can have a solid connection to ground but the center still needs
an arc path to ground), supplemental protection at the usage end can
still help and connecting that to the power circuit grounding conductor
would be how that is done.


| Residential AC electric service is three wires. One wire connects
| directly to earth groud as required by code. Other two need a
| protector to make that connection. Connecting (to shunt, divert,
| clamp, conduct) those other two wires to earth means a protector. So
| we install a 'whole house' protector as sold by responsible
| manufacturers - with a dedicated earthing wire. Without that earthing
| wire, what does the protector do? Simply connects a surge from one
| wire to all others - a surge still looking for earth ground - a
| problem demonstrated on Page 42 Figure 8.

Yes, the earthing wire at the entrance is an absolute necessity.

I would not call a breakdown device like an MOV or an arc gap to be
a "connection" to ground. But if you want to use that term, maybe
you can at least refer to the connection of the neutral on the power
and the shield of the coax as "solid connection" in reference to the
all time metallic path to ground they have (where installed right).


| How are destructive surges generated inside a building? Protection
| inside appliances routinely makes those surges irrelevant. Are we
| trooping every day to hardware stores to replace dimmer switches,
| furnace controls, clock radios, and dishwashers? Of course not. But
| they have no protectors - therefore must be damaged every day?
| Internal appliance protection was routine AND even defined by industry
| standards over 30 years ago. If household appliances create surges,
| then that appliance is first destroying itself. If household
| appliances create surges, then protection must be inside that surge
| generating appliance. And finally a 'whole house' protector is so
| robust as to also make those appliance generated surges irrelevant.
| Maybe five in an even longer list of reasons why household surges only
| exist where myth purveyors are mistaken as informed.

If the building is struct directly by lighting, that can definitely
introduce a big surge on metallic paths. Looking for a path to ground,
the lightning can spread out and find a lot of different metal, such as
branch circuit wiring, telephone wires, cable coax, CAT5 between
computers, speaker wires, alarm wiring, etc. Protecting all this from
such rare occurrences can be tough, expensive, and perhaps just not
worth doing. But it is a real source of in-building surges that do
get entirely quenched by a whole house protector at the entrance (since
lightning found a different way in).


| Induced surges from nearby lightning? Put numbers to it. Lightning
| can induce thousands of volts on open ended wires AND long wire
| antennas. How do we make such induced surges irrelevant? Even an
| NE-2 neon glow lamp will conduct millamps from that long wire antenna.
| Thousands of volts drops to near zero when conducted by that neon
| lamp.. Even protection inside appliances easily makes such induced
| surges irrelevant. We install protectioni from direct lightning
| strikes. That same protection and protection already inside
| appliances makes less surges irrelevant.

At least 1 (you wanted a number) for me. I unplugged the stereo system.
Yet the surge was so significant as to destroy all the amplifier output
stage transistors and melt down the tweeter coils (woofer coils were OK).
It was certainly not protected from a big surge induced on the speaker
wires. Maybe such protection would have been easy to do. But it was
not there.

Do all appliances really have such internal protection for the level of
surge typically induced by a nearby strike? I think most do not.


| Finally, primary protection is not a 'whole house' protector. Each
| protection layer is defined by one component: the earthing
| electrode. Primary protection should be inspected:
| http://www.tvtower.com/fpl.html

Obviously examples of un-inspected protection.


| Secondary protection is defined by building earthing and connection
| (protector) to that earthing. How does a plug-in protector then
| protect what those other layers did not? Remember what a protector
| does:
| http://www.nemasurge.com/help.html
|> Ideally, protection should be installed at the main service entrance
|> as close to the N-G (neutral-to-ground) bond as possible. This will
|> ensure that surge energies are routed to earth by the most direct
|> path.
|
| Or from NIST Page 17:
| http://www.nist.gov/public_affairs/practiceguides/surgesfnl.pdf
|> A very important point to keep in mind is that your
|> surge protector will work by diverting the surges to
|> ground. The best surge protection in the world can
|> be useless if grounding is not done properly.
|
| So where is this layered protection without earthing? It does not
| exist - except in myths where a 'magic box' is somehow considered
| protection.
|
| Supplementary protector is not another shunt mode (plug-in)
| protector. Supplementary protector would be a series mode - such as
| filters from Brickwall, Surgex, or Zerosurge. Such solutions cost in
| excess of $100. Whereas shunt mode protectors work by connecting
| (clamping, diverting) to earth ground, series mode protectors blocking
| surge currents. Not blocking like a dam. Typically destructive
| surges are not stopped or absorbed - would blow through that dam.
| Series mode protectors block by operating like a dike - divert the
| flood downstream - as part of a larger 'system' that diverts so that
| surges cause no damage.

I did once build a blocking surge protector. It actually worked.
But it is really too expensive to keep replacing.

But I disagree with part of this. A plug-in shunt mode protector
can be a supplementary protector. It's not the best, but it is
better than not having anything there at all. Other things can
help, or just do better.

The sad part of the plug-in protectors is that people think that
they are completely protected. And that is so far from true.


| Piggy's cable guy is correct about the $90 belkin for too many
| reasons. First it is a shunt mode protector that has no dedicated
| earthing; cannot shunt How then can it supplement protection?

If it connects to power circuit ground, it at least offers some
limited amount of protection. It should not be the only protection.
But it can't hurt to have it (unless one thinks it is all that is
needed).


| Second, it would only degrade cable signals. Third, anything that
| protector would do for cable coax conductors is already accomplished
| by earthing where cable enters the building - that all so critical
| single point earth ground.

Depending on design, it may degrade the signal. I've seen some that
definitely do not (but they are more expensive).

The earthed protection at the entrance would be the main protection
for surges coming in from outside (most surges). But I would not
depends on it being the complete protection.

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| Phil Howard KA9WGN (ka9wgn.ham.org) / Do not send to the address below |
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