Re: Soon to arrive my HDTV

w_tom wrote:
> On Apr 4, 10:18 pm, Cinderl...@[EMAIL PROTECTED]
 (Cinder Lane) wrote:
>> W_tom, you have stated many times in this thread that wall receptacles
>> do not have earth grounds.  What about wall receptacles in concrete and
>> steel buildings?  Aren't they in direct contact with earth ground?
>>
>> Also, for the sake of arguement, let's assume that you are correct --
>> that because of high inductance, wall outlets do not have a "true"
earth
>> ground according to the IEEE definition.  Are you saying that ALL
>> plug-in surge suppressors offer NO protection whatsoever?
 >
>   Plug-in protectors protect from one type of surge.  A surge often
> made irrelevant by protection already inside all appliances.  Another
> type of surge that overwhelms protection inside appliances, instead,
> seeks earth ground.
..
Complete nonsense. Plug-in suppressors are required by UL to have MOVs 
(protective elements) from H-N, H-G, N-G. That is all possible 
combinations and all possible surges.
..
> That same 'whole house' protector also
> provides protection from that first type surge. 
..
And repeating from the NIST guide:
"Q - Will a surge protector installed at the service entrance be 
sufficient for the whole house?
A - There are two answers to than question: Yes for one-link appliances 
[electronic equipment], No for two-link appliances [equipment connected 
to power and signal]. Since most homes today have some kind of two-link 
appliances, the prudent answer to the question would be NO - but that 
does not mean that a surge protector installed at the service entrance 
is useless."

But I agree that a service panel suppressor is a good idea.
..
> So plug-in
> protectors don't claim any protection.
..
More complete nonsense.
..
> All incoming utilities must
> make that short (ie 'less than 10 foot') connection to the same earth
> electrode.  One utility discusses this in:
>     http://www.cinergy.com/surge/ttip08.htm
..
You do not *just* want entry protectors from phone and cable to be 
connected to the same electrode. You want them connected with a *short* 
wire to the ‘ground’ at the power service. The goal is not just earthing 
surges. The primary goal is minimizing the voltage between power, cable 
and phone wires.

Repeating from the author of the NIST guide  "the impedance of the 
grounding system to `true earth' is far less im****tant than the 
integrity of the bonding of the various parts of the grounding system."

If anyone looked at the cinergy link, the “right” picture is totally 
inadequate for surge protection. Only the “preferred” picture is correct.
..
> Cable TV needs
> no 'box'.  Cable TV uses 12 AWG wire and a $2 ground block (visit any
> hardware store to view it) connected directly to earth ground.  No
> 'box' required for protection.
..
“Needs no box”?  The IEEE guide says “there is no requirement to limit 
the voltage developed between the core and the sheath. .... The only 
voltage limit is the breakdown of the F connectors, typically ~2–4 kV.” 
  And "there is obviously the possibility of damage to TV tuners and 
cable modems from the very high voltages that can be developed, 
especially from nearby lightning."  A “box” will limit the voltage from 
core to ****eld.
..
>   Typical lightning strikes are 20,000 amps.  Strikes of 60,000 amps
> means a surge incoming on a residence might be as high as 20,000
> amps. 
..
Francois Martzloff was the NIST surge guru and wrote the NIST guide. He 
has also written numerous technical papers on surges and surge 
protection. One of them looked at a lightning strike to the primary wire 
on top of a pole behind a house for typical urban distribution. The 
lightning strike was an extremely strong 100,000A. On average for the 
US, the estimated probability of a worse event is once in 8,000 years. 
Of the 100,000A, 33,000A went toward the house on the neutral. The surge 
that stayed on the neutral is earthed by the neutral-ground-earth 
connection in US services. A fraction of the 33,000A would couple to the 
‘hot’ wires. The result is more like 10,000A from a near-worst-case 
lightning strike.

But when the voltage at a service panel reaches about 6,000V (US) there 
is arc-over from the panel 'hot' busbars to panel ground. Once the arc 
is established, the voltage across the arc is hundreds of volts. This 
dumps most of the remaining surge to earth.

In a different paper Martzloff looks at the amount of energy absorbed in 
a MOV on a branch circuit. The impedance of a branch circuit greatly 
limits the current, and thus energy, that can reach a plug-in 
suppressor. With surge currents up to 10,000A, the amount of energy 
absorbed by the MOV was surprisingly small, 35J max. The reason is most 
of the energy is dumped to earth by arc-over at the service panel. The 
highest energies that reached the MOV were for short (30 meter) branch 
circuits and surprisingly for low surge currents. With lower surge 
currents the MOV could clamp the voltage at the source to below 6,000V 
so there was no arc-over. With arc-over the max energy absorbed was 1.1J 
max.

Note that neither service panel suppressors or plug-in suppressors 
protect by absorbing energy. But both absorb energy in the process of 
protecting.
..
> a protector is only as effective as its earth
> ground
..
And the mandatory religious mantra.

But - what a surprise - still no links to anyone who agrees with w_ that 
plug-in suppressors are NOT effective.  I am beginning to suspect that 
w_ is full of crap.

-- 
bud--