|
Home > Archive > Electrical Engineering > April 2006 > surge protector question
You are viewing an archived Text-only version of the thread.
To view this thread in it's original format and/or if you want to reply to
this thread please [click here]
| Author |
surge protector question
|
|
| nickravo 2006-04-09, 8:21 pm |
| If I plug my surge filter (Brick Wall Series by Price Wheeler) in a
power strip in stead of directly into the wall outlet, does it (the
Brick Wall) lose its effectiveness asgainst surges from lightening,
etceterta?
| |
| Bill Kaszeta / Photovoltaic Resources 2006-04-10, 1:21 am |
| On 9 Apr 2006 15:48:52 -0700, "nickravo" <nickravo@gmail.com> wrote:
>If I plug my surge filter (Brick Wall Series by Price Wheeler) in a
>power strip in stead of directly into the wall outlet, does it (the
>Brick Wall) lose its effectiveness asgainst surges from lightening,
>etceterta?
>
Basically, yes.
By doing so you have increased the resistance of the grounding path
that the surge arrestor uses to shunt the surge to ground.
Bill Kaszeta
Photovoltaic Resources Int'l
Tempe Arizona USA
bill@pvri-removethis.biz
| |
|
| Bill Kaszeta / Photovoltaic Resources wrote:
> On 9 Apr 2006 15:48:52 -0700, "nickravo" <nickravo@gmail.com> wrote:
>
>
>
> Basically, yes.
>
> By doing so you have increased the resistance of the grounding path
> that the surge arrestor uses to shunt the surge to ground.
>
> Bill Kaszeta
> Photovoltaic Resources Int'l
> Tempe Arizona USA
> bill@pvri-removethis.biz
Ummm ... check out their site:
http://www.pricewheeler.com/howwork.htm
The thing does not shunt the surge to ground.
Whatever the effectiveness of that supressor is, it
won't lose any effectiveness by being plugged into
a power strip.
Ed
| |
| nickravo 2006-04-10, 8:21 am |
| Ok. Lovely. I have two authorative sounding answers here. Which one do
I choose?
| |
| Palindr☻me 2006-04-10, 10:21 am |
| nickravo wrote:
> Ok. Lovely. I have two authorative sounding answers here. Which one do
> I choose?
>
Both of them. They are both correct.
For *some* surges, the thing will do the job by altering the shape of
the transient by blocking the highest frequency components. Some
transient energy, not much, will be absorbed by the snubber. If the
surge is of short enough duration, so that all the energy is in these
high frequency components, this is all that is needed.
For longer surges, significant energy will pass through the reactor.
This energy is not absorbed by the thing but dumped into the neutral
line. Now if the equipment being "protected" has another earth
connection, eg a modem lead, then some of the surge energy will flow
from the neutral line through the equipment and into that earth
connection - much the same as it would if the thing wasn't there at all.
The further the thing is installed back towards the point that the earth
is bonded to neutral, the less the voltage rise on the neutral line and
the less the energy that will go through the "protected" equipment to
earth.
So plugging the thing into a power strip is better than nothing and will
give protection from some surges. Plugging the thing into a wall socket
will give protection for a wider range of surges. Having a surge
protector right where the lines come into the house, where the
electrical path to earth is shortest, will give the most protection of all.
This is for surges arriving on the power lines. For surges arriving on
telephone lines, the same rules apply. The shorter the electrical path
from surge protector to ground, the better.
--
Sue
| |
| nickravo 2006-04-10, 12:21 pm |
| Ok, which is better; Plugging my receiver and computer into a Brick
Wall surge device that is plugged into a power strip. Or just plugging
it into a power strip and getting rid of the Brick Wall device?
Palindr=E2=98=BBme wrote:
> nickravo wrote:
> Both of them. They are both correct.
>
> For *some* surges, the thing will do the job by altering the shape of
> the transient by blocking the highest frequency components. Some
> transient energy, not much, will be absorbed by the snubber. If the
> surge is of short enough duration, so that all the energy is in these
> high frequency components, this is all that is needed.
>
> For longer surges, significant energy will pass through the reactor.
> This energy is not absorbed by the thing but dumped into the neutral
> line. Now if the equipment being "protected" has another earth
> connection, eg a modem lead, then some of the surge energy will flow
> from the neutral line through the equipment and into that earth
> connection - much the same as it would if the thing wasn't there at all.
>
> The further the thing is installed back towards the point that the earth
> is bonded to neutral, the less the voltage rise on the neutral line and
> the less the energy that will go through the "protected" equipment to
> earth.
>
> So plugging the thing into a power strip is better than nothing and will
> give protection from some surges. Plugging the thing into a wall socket
> will give protection for a wider range of surges. Having a surge
> protector right where the lines come into the house, where the
> electrical path to earth is shortest, will give the most protection of al=
l=2E
>
> This is for surges arriving on the power lines. For surges arriving on
> telephone lines, the same rules apply. The shorter the electrical path
> from surge protector to ground, the better.
>=20
> --=20
> Sue
| |
|
| nickravo wrote:
>
> Palindr☻me wrote:
>
The neutral voltage will be lifted away from ground but there should be
no ground current and the ground for the power and telephone shouldn't
separate. That assumes the surge is only on the power line and there are
no MOVs or other devices that clamp the neutral and hot voltages to ground.
The power supply on a computer and maybe other equipment is likely to
have clamps, which will produce a ground current and voltage drop, which
will lift the power ground away from 'absolute' ground/earth, which will
separate the voltage from equipment ground to telephone line (or other
electrical connections), which may excede the equipment ratings and
damage it as described.
[color=darkred]
It is not obvious to me the effect of adding some series resistance to a
low pass filter.
[color=darkred]
For clamp devices, which are the common method of surge suppression, the
devices should clamp to the same reference point. In the US the power
neutral is connected to ground/bond at the service, so the telephone
protector, cable protector ... should be located very near this point
and connected at low resistance close to this point. That way all
voltages are kept close to the same reference level. (Not sure how power
grounding works in the UK.) That, IMHO, is a lot more important than the
connection from that reference point to earth. Any
surge-conducted-to-earth will lift that reference point from 'absolute'
ground.
A surge protector with clamp devices that is installed at a computer, or
other equipment, is better than no protection, and if it has in-out
connections for telephone or other external wires it should provide good
protection. (The wires will be clamped to a common reference point.) (Do
computers have good clamp devices from power/phone/... to the power
ground connection?)
[color=darkred]
> Ok, which is better; Plugging my receiver and computer into a Brick
> Wall surge device that is plugged into a power strip. Or just plugging
> it into a power strip and getting rid of the Brick Wall device?
>
I agree with Ed (ehsjr), who cheated and found a device schematic, that
the power strip should be no problem. Using the device should be better
than not using the device.
Surge suppressors generaly work:
by clamping the voltage H-N, H-G, N-G (usually with MOVs)
and by using a low pass filter to remove fast rising voltages .
Almost all devices include clamps. Your device only uses a low pass
filter - but presumably a very good one. As Ed said "whatever the
effectiveness of the supressor..."
bud--
| |
|
| nickravo wrote:
> Ok. Lovely. I have two authorative sounding answers here. Which one do
> I choose?
>
Neither. An authoritative sounding post will do nothing
to protect your equipment - and may give you a false sense
of security. You may have made an assumption that the surge
protector will offer a tremendous amount of protection. It
might, under some circumstances, but it is not the best way
to go.
With regard to the use of the power strip:
In some, but not all, circumstances, the extra length of the
power strip cord - say 6' - will cause a very small change in
the effectiveness - small enough to be ignored. Shortening
the distance to ground by 6' by plugging the thing into the
wall receptacle vs the power strip is irrelevant in practical
terms. The receptacle itself is already installed a good
distance from ground - far greater than 6', and any voltage
rise on the neutral in the scenario Sue mentioned will be
primarily due to that length, not the 6' feet in the power
strip. If you want to strain at gnats, conceivably, one could
imagine a scenario where that extra 6' made a difference.
But it is extremely improbable.
That said, why not ask about how to establish good
surge protection? It does not start with a point of use
surge supressor. As Sue correctly pointed out, better
protection is achieved closer to ground - at the service
entry panel:
"Having a surge protector right where the lines come
into the house, where the electrical path to earth is
shortest, will give the most protection of all. "
Point of use protectors are supplemental to that.
There is a let through voltage rating for "whole house"
protectors, and the point of use protector may protect
your equipment from whatever the whole house protector
lets through.
If you want *really* good surge protection, you have to
work at it. It starts with an excellent grounding electrode
system and a short, straight grounding electrode conductor
from the service panel to the ground system. The ground for
all cables entering the house is bonded to that system.
A whole house protector is installed. Point of use protectors
can be added at the equipment.
Ed
| |
| SQLit 2006-04-10, 10:21 pm |
|
"nickravo" <nickravo@gmail.com> wrote in message
news:1144678636.004850.213520@g10g2000cwb.googlegroups.com...
Ok, which is better; Plugging my receiver and computer into a Brick
Wall surge device that is plugged into a power strip. Or just plugging
it into a power strip and getting rid of the Brick Wall device?
Diving out the clouds, SQLit says,,,,
If you think that plugging in a device anywhere in your house and you get
protection from surges your misguided.
IEEE 519 states that for effective protection you MUST provide protection in
two of the 3 zones availble.
Zone one is on the utility side,, that is out.
Zone two is your service,
Zone three is point of use.
( ok I paraphased it and made it a lot simpler )
I buy the plug in surge protectors for my panel and it has a let through of
say 900 joules. The plug strips I use do shunt to the ground and their peak
is about 900 joules and with any luck they will drop it down to an
acceptable level that the electronics can handle. Since all of the stuff I
use works on MOV's I change the house protector out even years and the plug
strips on the odd years. U.L. tests this stuff for one hit, not two hits or
three.
This concept will not protect you from lightning. NOTHING will. I have used
this method for 10 years and have not lost anything yet. Now that I said
that I will.
Want to protect your equipment? Get a service panel protector and keep what
you have for point of use.
Palindr?me wrote:
> nickravo wrote:
> Both of them. They are both correct.
>
> For *some* surges, the thing will do the job by altering the shape of
> the transient by blocking the highest frequency components. Some
> transient energy, not much, will be absorbed by the snubber. If the
> surge is of short enough duration, so that all the energy is in these
> high frequency components, this is all that is needed.
>
> For longer surges, significant energy will pass through the reactor.
> This energy is not absorbed by the thing but dumped into the neutral
> line. Now if the equipment being "protected" has another earth
> connection, eg a modem lead, then some of the surge energy will flow
> from the neutral line through the equipment and into that earth
> connection - much the same as it would if the thing wasn't there at all.
>
> The further the thing is installed back towards the point that the earth
> is bonded to neutral, the less the voltage rise on the neutral line and
> the less the energy that will go through the "protected" equipment to
> earth.
>
> So plugging the thing into a power strip is better than nothing and will
> give protection from some surges. Plugging the thing into a wall socket
> will give protection for a wider range of surges. Having a surge
> protector right where the lines come into the house, where the
> electrical path to earth is shortest, will give the most protection of
all.
>
> This is for surges arriving on the power lines. For surges arriving on
> telephone lines, the same rules apply. The shorter the electrical path
> from surge protector to ground, the better.
>
> --
> Sue
| |
| TimPerry 2006-04-11, 12:21 am |
|
"nickravo" <nickravo@gmail.com> wrote in message
news:1144678636.004850.213520@g10g2000cwb.googlegroups.com...
Ok, which is better; Plugging my receiver and computer into a Brick
Wall surge device that is plugged into a power strip. Or just plugging
it into a power strip and getting rid of the Brick Wall device?
a surge suppressor is like a first aid kit: it might save your life but you
might die anyway 
| |
|
| IEEE 519 is not relevant:
> IEEE 519 - Recommended Practices and Requirements for Harmonic
> Control in Electrical Power Systems
Harmonics being totally irrelevant to this discussion.
Meanwhile IEEE does not define three zones that must include
protectors. IEEE defines parameters typical of three zones; that an
appliance or protector could expect. Numbers for each zone provide
benchmarks so that, for example, a protector manufacture will construct
his product to not endanger human life. Both IEEE 587 and BS6551
provide same numbers and don't demand protectors in each location:.
Category C - supply side of mains panel could experience up to 20K
volts and 10K amps.
Category B - mains box could experience up to 6K volts and 3K amps
Category A - inside building and at least 10 meters from the mains box
- 6K volts and 500 amps.
ANSI/IEEE C62.41 then defines waveforms for these locations.
Waveforms used by UL for 1449 testing. Not testing that a protector
works. UL does not care. Testing that a protector - even if 100%
failed - still does not endanger humans. That's right. A protector
can completely fail - provide no effective protection - and still be
UL1449 approved.
What does IEEE 587 do? From Wiley's Encyclopedia of 1999:
> ... proposes three location categories for low voltage ac power
> circuits that are representative of a majority of locations from
> the electrical service entrance to the most remote wall outlet.
Again, no IEEE requirement for protectors in all three zones. Just
numbers so that engineers can better design appliances and a protection
system.
Those three zones define what one (in the US or UK) might expect from
a transient such as lightning. IEEE does not demand that protectors
be in all three zones. IEEE only defines three zones. A 'whole house'
protector is category B - 'secondary protection'. Category C is
location of 'primary protection' as provided by the utility. A
homeowner should also inspect those Category C earthings since earthing
determines system effectiveness.
Meanwhile a power panel protector does not have a "let through of 900
joules". Let through is a voltage. 900 joules - something different -
determines protector's life expectancy. Two different (and confused)
parameters that define a protector.
If one must swap out a protector every two years, then that
protector is obviously undersized. As joules increase, a protector's
life expectancy increases exponentially. A 'whole house' protector
should be sufficiently sized to remain functional more than 10 years -
especially since transients sufficient to trigger a protector would
occur typically once every eight years. A period that obviously varies
even within every town and with geology. A number that further
demonstrates why protectors need not be swapped out every other year.
Why do we install protectors? Lightning. Other transients obviously
made irrelevant by electronic appliance standards and from IEEE 142
(also called the Green Book):
> Lightning cannot be prevented; it can only be intercepted or
> diverted to a path, if well designed and constructed, not result
> in damage. Even this means is not positive, provided only by
> enclosing the object in a complete metal encapsulation.
> ... a 99.5% protection level will reduce the incidence of direct
> strokes from one stroke per 30 years ... to one stroke per
> 6000 years ...
So yes, nothing is 100%. Then we apply numbers. No protection
means near 0% protection. Properly earth protector means well over 90%
protection. How 'well over"? How good is your earthing? We install a
protection 'system' for the typically most destructive -lightning - and
also for other transients.
If appliances were so frequently at risk (require protector
replacement every other year), then homes without protectors would
require new dimmer switches every day or month. Why do dimmer switches
not fail constantly? Because those daily and weekly transients are
made irrelevant by appliance internal design. We install protection
systems for transients that would otherwise overwhelm internal
appliance protection; transients such as lightning.
A protector is not protection - no matter how some want to spin it.
A protector is only as effective as its *protection*. Protection is
earth ground as even noted by the green book. Superior earthing
creates better protection. A shunt mode protector is nothing more than
a connection to protection as even IEEE 142 noted. Protector acts like
a switch - nothing more. Eliminate the hype about protectors by
instead worrying about THE most critical component in a protection
'system' - earthing. Protector makes a temporary connection to
protection. No earth ground means no effective protection - which
explains why plug-in protector really don't claim to provide such
protection - as demonstrated by no numbers for such protection.
IEEE 519 - harmonics - is irrelevant to all of this. Those three
zones in IEEE 587 do not recommend protectors. The most critical
component in any protection 'system' is that single point earth ground.
SQLit wrote:
> Diving out the clouds, SQLit says,,,,
>
> If you think that plugging in a device anywhere in your house and you get
> protection from surges your misguided.
>
> IEEE 519 states that for effective protection you MUST provide protection in
> two of the 3 zones availble.
> Zone one is on the utility side,, that is out.
> Zone two is your service,
> Zone three is point of use.
> ( ok I paraphased it and made it a lot simpler )
>
>
> I buy the plug in surge protectors for my panel and it has a let through of
> say 900 joules. The plug strips I use do shunt to the ground and their peak
> is about 900 joules and with any luck they will drop it down to an
> acceptable level that the electronics can handle. Since all of the stuff I
> use works on MOV's I change the house protector out even years and the plug
> strips on the odd years. U.L. tests this stuff for one hit, not two hits or
> three.
>
> This concept will not protect you from lightning. NOTHING will. I have used
> this method for 10 years and have not lost anything yet. Now that I said
> that I will.
>
> Want to protect your equipment? Get a service panel protector and keep what
> you have for point of use.
| |
| nickravo 2006-04-11, 12:21 pm |
| Is there some way to get a simple one or two sentence clear answer?
| |
| Palindr☻me 2006-04-11, 1:21 pm |
| nickravo wrote:
> Is there some way to get a simple one or two sentence clear answer?
>
"Does it lose effectiveness?" Yes - it does lose /some/ effectiveness.
"Is it better than not having it at all?" - Yes.
--
Sue
| |
|
| Responsible manufacturers with names such as Square D, GE, Siemens,
Intermatic, Leviton, and Cutler Hammer sell 'whole house' protectors.
They are effective because they make the short connection to THE most
important component of a protection 'system': earth ground. Such
effective protectors are sold in Home Depot (Intermatic), in Lowes (GE
and Cutler Hammer), and in most electrical supply houses.
But the bottom line is earth ground. No earth ground means no
effective protection. Ineffecetive protectors are easily identified.
No dedjcated connecton to earth AND manufacturer avoids all discussion
about earthing. Notice what that IEEE green book discusses: diverting
the transient to earth. Earthing is your simple answer. If a
protector does not make the short earthing connection, then it is
ineffective.
This is your sound byte: A protector is only as effective as its
earth ground. No earth ground means no effective protecction.
nickravo wrote:
> Is there some way to get a simple one or two sentence clear answer?
| |
| Long Ranger 2006-04-12, 1:21 am |
| I got in here late on this topic, but wanted to add the following:
When I worked for a local government entity there was a concerted effort
at one point to equip some buildings with surge protection. We had all the
big name reps in person at one time or another, and they virtually all
agreed with the following:
1. 80-90% (depending on the guy talking.)of all transients, spikes, surges
originate in your own system, after the service.
2. A sharp bend in the input wires to a supressor can lower the effective
ratings of these devices dramatically.
It always stood out to me how a simple mistake like a curl in your wire
could lower the effectiveness of your device, and that the trouble we
normally view as "out there" is really "right here". Just my 2 cents..
| |
|
| w_tom wrote:
>
> This is your sound byte: A protector is only as effective as its
> earth ground. No earth ground means no effective protecction.
>
Thats your sound bite. I've read a lot of the many links you have put up
in other threads and none of them has agreed with you on this point. The
last thread several of your links liked plug in surge suppressors which
we both agree have poor ground paths.
bud--
| |
|
| Everything ever posted by Bud is wrong. Like Bud, I might make that
claim if not one single example or reason if provided. Bud, if those
links disagree with what was posted, and if you are to have
credibility, then you post specifics. Myths are promoted by
unsubstantiated claims such as:
> ... read a lot of the many links ... and none of them
> has agreed with you
I suspect you don't post specifics only because you want to
criticize and not be caught lying. So prove me wrong. Show us where
those links don't agree with what was posted. Your current post is a
classic example of Rush Limbaugh propaganda - big claims and no
supporting facts. Show us. Show us were citations do not agree. Cite
specifics and numbers. I expect you to cite examples if you disagree.
I have provided numerous citations, underlying science, numbers, and
even specific products from more responsible manufacturers and
retailers - whereas you have only accused. I hope the topmost sentence
is not going to be proven accurate. Show us.
Bud-- wrote:
> Thats your sound bite. I've read a lot of the many links you have put up
> in other threads and none of them has agreed with you on this point. The
> last thread several of your links liked plug in surge suppressors which
> we both agree have poor ground paths.
| |
|
| w_tom wrote:
> Everything ever posted by Bud is wrong. Like Bud, I might make that
> claim if not one single example or reason if provided. Bud, if those
> links disagree with what was posted, and if you are to have
> credibility, then you post specifics. Myths are promoted by
> unsubstantiated claims such as:
>
>
>
> I suspect you don't post specifics only because you want to
> criticize and not be caught lying. So prove me wrong. Show us where
> those links don't agree with what was posted. Your current post is a
> classic example of Rush Limbaugh propaganda - big claims and no
> supporting facts. Show us. Show us were citations do not agree. Cite
> specifics and numbers. I expect you to cite examples if you disagree.
> I have provided numerous citations, underlying science, numbers, and
> even specific products from more responsible manufacturers and
> retailers - whereas you have only accused. I hope the topmost sentence
> is not going to be proven accurate. Show us.
>
> Bud-- wrote:
>
3-06 thread - you put the link to
http://www.polyphaser.com/ppc_ptd_home.aspx
My response:
"This link just has links to about 30 papers. The problem with
polyphaser is it is concerned with transmitters. Transmitters, even
amateur, have antennas that stick up above everything else and make good
lightning rods. This is a useful source for amateurs, but not in general
for others. It does heavily stress single point service grounding.
Kindly do not use this link; use links to specific papers that are
relevant."
I said the same thing in a previous thread.
Is there a single Polyphaser paper that supports your view: "A protector
is only as effective as its earth ground. No earth ground means no
effective protecction."
[color=darkred]
>
3-06 thread - you provided links
http://www.nist.gov/public_affairs/...s/surgesfnl.pdf
http://www.keison.co.uk/bowthorpe/d...ion%20Guide.pdf
Both advocate plug-in point of use surge suppressors which by your
argument are useless because they have high resistance to earth, which I
pointed out. They do not support "A protector is only as effective as
its earth ground. No earth ground means no effective protecction."
Are these examples from a previous thread, which you theoretically read,
specific enough? I actually thought you might remember.
You have said several times in another newsgroup: "Water pipe is no
longer acceptable as an earth ground" [because another ground electrode
is required].
From the National Electrical Code Handbook - 1996 published by the NFPA
under 250.81(a)
"The requirement to supplement the metal water pipe is based on the
practice of using plastic pipe for replacement when the original metal
water pipe fails. This leaves the system without a grounding electrode
un0nless a supplementary electrode is provided." The NFPA also publishes
the NEC - maybe they would know if water pipe is an acceptable grounding
electrode. Is that specific enough?
3-06 thread - Charles Perry said you mischaracterized the views of his
colleage Dr. Mansoor. Is that specific enough?
What are your one or two links that clearly support "A protector is only
as effective as its earth ground. No earth ground means no effective
protection." I have searched in vain through many of your previous links.
bud--
| |
| w_tom 2006-04-13, 12:21 pm |
| Bud claimed:
> Transmitters, even amateur, have antennas that stick up above
> everything else and make good lightning rods.
As was noted back then, household electronic appliances are also
connections to antenna like devices - called AC electric and telephone
utility wires. To lightning, utiliity wires are no different than a
radio station antenna. Those Polyphaser app notes on radio
transmitters and other facilities (yes, Polyphaser discusses more than
radio transmitters) such as telephone communication equipment all
describe same protection techniques required for household PC, portable
phone base station, television, etc. Protection so well proven for
radio stations is installed in homes to make direct lightning strikes
mostly irrelevant.
No science paper will provide a sound byte if seeking a direct quote.
Science papers stick to specific science points - concepts. Sound byte
is obvious from those concepts, Some consumers (such as nickravo)
asked for science dumbed down to a sound byte. What is the most
critical component in every protection system? Single point earth
ground. "Protection system is only as effective as its earth ground".
What is effective ground? Defined in terms of equipotential,
conductivity, and how connections are made to that earthing 'system'.
A sound byte summary are concepts dumbed down to ony a few words.
Understand the concepts and that sound byte is obvious.
What does experience demonstrate? Among other things, that an
'equipotential only' solution is not sufficient:
> 3 - Common point clamping is more important than grounding
Yes common point clamping - equipotential - is effective as a building
wide solution if used in conjunction with good connection (low
impedance) to earth. Alone, (without conductivity to earth)
equipotential is not effective. And equipotential (bonding) cannot be
achieved inside a typical room. Equipotential would require a
specially constructed room - a faraday cage.
In the cited 6 March discussion, early Martzloff, et al started by
promoting MOVs (surge protectors devices) for protection. Over
decades, protectors were less often recommended.
So what were Martzloff and Mansoor moving towards? They moved on to
study a building wide protection 'system' using the Upside-Down house.
Francois Martzloff and Thomas Key in 1994 wrote in "Surging the
Upside-Down House: Looking into Upsetting Reference Voltages"
> Conclusion:
> 1) Quantitative measurements in the Upside-Down house clearly
> show objectionable difference in reference voltages. These occur
> even when or perhaps because, surge protective devices are
> present at the point of connection of appliances.
In 1995, Martzloff, Arshad Mansoor, and Grady wrote "Surging the
Upside-Down House: Measurements and Modeling Results" where
connections to earthing in relation to two port appliances were
studied. Trying to quantify these 'objectionable differences in
reference voltages' that cause appliance problems.
Did Mansoor, et al study 'point of use' protectors in 1995? No. The
problem with such protectors was described in the above 1994 paper.
They studied various ways that appliances are connected to utilities
AND utilities are earthed at the service entrance. They studied
objectionable voltages and how the 'building' connection to earthing
creates or subverts protection. One example studied is an NIST figure
I cited back on 6 Mar from:
http://www.epri-peac.com/tutorials/sol01tut.html
A url maybe confused with the www.nist.gov brochure erroneously
attributed to me. Mansoor, Martzloff, and Grady expanded on
objectionable voltages
> even when or perhaps because, surge protection devices are present ...
I never provided that www.nist.gov citation. However what does
that link also state?
> You cannot really suppress a surge altogether, nor "arrest" it (although
> your utility uses devices they call "surge arresters" to protect their
> systems). What these protective devices do is neither suppress nor
> arrest a surge, but simply divert it to ground, where it can do no harrm.
Funny. That is what I was saying repeatedlywith supporting citations
That is what the sound byte says.
So which protectors have that necessary ground connection? Well
that www.nist.gov brochure does not even discuss the most critical
part of a protecton 'system' - earth ground. Which protector can
"divert it to ground where it can do no harm"? Never mentioned.
Reader must somehow discover which protector has no low impedance
earthing connection. Somehow a plug-in protector will divert to an
earth ground that all but does not exist? They also don't mention that
an AC power protector of only a few hundred joules is grossly
undersized. Joules determines protector life expectancy. I would
never cite this url. It is too vague. It declares as bad if utilities
enter at multiple locations; does not even say why. No single point
earth ground is the unprovided answer. No equipotential. No solution
provided to correct that equipotential problem. I would never cite
this url that was attributed to me.
Meanwhile in that 6 Mar discussion were what - maybe 30 other
citations that also demonstrate effective protection, earthing, and
personal testimony as to why earthing is so effective. Bud says none
of my citations do so. Even the Polyphaser citation - highly regarded
by industry professionals - demonstrates the concept. A concept that
applies to radio stations as well as household - two port - appliances.
Again this Martzloff and Key criticism of plug-in protectors:
> ... objectionable difference in reference voltages ... occur
> even when or perhaps because, surge protective devices are
> present at the point of connection of appliances.
Previous posts also demonstrated how plug-in protectors even
contributed to damage of adjacent and powered off computers.
Bud-- wrote:
> 3-06 thread - you put the link to
> http://www.polyphaser.com/ppc_ptd_home.aspx
> My response:
> "This link just has links to about 30 papers. The problem with
> polyphaser is it is concerned with transmitters. Transmitters, even
> amateur, have antennas that stick up above everything else and make good
> lightning rods. This is a useful source for amateurs, but not in general
> for others. It does heavily stress single point service grounding.
> Kindly do not use this link; use links to specific papers that are
> relevant."
> I said the same thing in a previous thread.
> Is there a single Polyphaser paper that supports your view: "A protector
> is only as effective as its earth ground. No earth ground means no
> effective protecction."
> ...
>
> 3-06 thread - you provided links
> http://www.nist.gov/public_affairs/...s/surgesfnl.pdf
> http://www.keison.co.uk/bowthorpe/d...ion%20Guide.pdf
> Both advocate plug-in point of use surge suppressors which by your
> argument are useless because they have high resistance to earth, which I
> pointed out. They do not support "A protector is only as effective as
> its earth ground. No earth ground means no effective protecction."
> ...
>
> 3-06 thread - Charles Perry said you mischaracterized the views of his
> colleage Dr. Mansoor. Is that specific enough?
>
> What are your one or two links that clearly support "A protector is only
> as effective as its earth ground. No earth ground means no effective
> protection." I have searched in vain through many of your previous links.
>
> bud--
| |
| w_tom 2006-04-13, 12:21 pm |
| If I have only A, the code says that is not sufficient. If I have A
and B, then that is sufficient. If I have A and C, then that is
sufficient. If I have A, B, & C or if I have only B & C, then that is
sufficient.
IOW B or C is required. A alone does not meet code - is not
sufficient.
A is earthing via a cold water pipe. B & C are other 'supplemental'
earthing electrodes. B or C are sufficient to meet code. A - a water
pipe earth ground is not sufficient as an only earthing electrode.
This in direct contradiction to what Bud has posted:
> You have said several times in another newsgroup: "Water pipe is no
> longer acceptable as an earth ground" [because another ground
> electrode is required].
> From the National Electrical Code Handbook - 1996 published by the
> NFPA under 250.81(a) ...
First, Article 250.81(a) has been removed from code. NEC Article
250.52(A) lists seven earthing electrodes that are legal. Only one is
insufficient. Only one that can be added to a earthing system but is
not sufficient is the cold water pipe. To put that quoted sentence in
proper context - "Water pipe is no longer acceptable as an only
earthing electrode." I posted accurately and quoted code: Article
250.53(D)(2).
Post 2000 code does not (anywhere I can find) even discuss plastic
pipe. Many reasons besides plastic pipe for why cold water pipe is not
sufficient as an earthing ground. Post 1990 code requires that some
other earthing electrode be installed - as was accurately stated.
That cold water pipe is no longer sufficient for earthing (and some
exceptions exist). So why do you claim otherwise when even your own
obsoleted code says that cold water pipe is not sufficient?
I asked you to cite specific examples of where I was wrong. You
cited code that has long been obsoleted AND you cited obsolete code
that only agrees with my statement. Cold water pipe cannot be the
building's only earth ground as even (apparently) stated in obsolete
Article 250.81(a). Any other earthing electrode (called a supplemental
electrode) is sufficient, alone, to earth a building. But cold water
pipe is no longer sufficient for earthing.
Article 250.81(a) somehow proves "many links you have put up in
other threads and none of them has agreed with you"? It somehow
defines surge protection?
Accurately posted: A protector is only as effective as its earth
ground. No earth ground means no effective protection. After all, how
does a protector "divert" to earth when not connected to earth? My
many citations repeatedly discuss THE most critical component in any
protection 'system': earthing.
And NEC is quite specific: cold water pipe is no longer sufficient
for a building's earthing electrode.
Bud-- wrote:
> ...
> Are these examples from a previous thread, which you theoretically read,
> specific enough? I actually thought you might remember.
>
> You have said several times in another newsgroup: "Water pipe is no
> longer acceptable as an earth ground" [because another ground electrode
> is required].
> From the National Electrical Code Handbook - 1996 published by the NFPA
> under 250.81(a)
> "The requirement to supplement the metal water pipe is based on the
> practice of using plastic pipe for replacement when the original metal
> water pipe fails. This leaves the system without a grounding electrode
> un0nless a supplementary electrode is provided." The NFPA also publishes
> the NEC - maybe they would know if water pipe is an acceptable grounding
> electrode. Is that specific enough?
| |
| Tom Horne, Electrician 2006-04-13, 3:21 pm |
| w_tom wrote:
> If I have only A, the code says that is not sufficient. If I have A
> and B, then that is sufficient. If I have A and C, then that is
> sufficient. If I have A, B, & C or if I have only B & C, then that is
> sufficient.
>
> IOW B or C is required. A alone does not meet code - is not
> sufficient.
>
> A is earthing via a cold water pipe. B & C are other 'supplemental'
> earthing electrodes. B or C are sufficient to meet code. A - a water
> pipe earth ground is not sufficient as an only earthing electrode.
> This in direct contradiction to what Bud has posted:
>
> First, Article 250.81(a) has been removed from code. NEC Article
> 250.52(A) lists seven earthing electrodes that are legal. Only one is
> insufficient. Only one that can be added to a earthing system but is
> not sufficient is the cold water pipe. To put that quoted sentence in
> proper context - "Water pipe is no longer acceptable as an only
> earthing electrode." I posted accurately and quoted code: Article
> 250.53(D)(2).
>
> Post 2000 code does not (anywhere I can find) even discuss plastic
> pipe. Many reasons besides plastic pipe for why cold water pipe is not
> sufficient as an earthing ground. Post 1990 code requires that some
> other earthing electrode be installed - as was accurately stated.
> That cold water pipe is no longer sufficient for earthing (and some
> exceptions exist). So why do you claim otherwise when even your own
> obsoleted code says that cold water pipe is not sufficient?
>
> I asked you to cite specific examples of where I was wrong. You
> cited code that has long been obsoleted AND you cited obsolete code
> that only agrees with my statement. Cold water pipe cannot be the
> building's only earth ground as even (apparently) stated in obsolete
> Article 250.81(a). Any other earthing electrode (called a supplemental
> electrode) is sufficient, alone, to earth a building. But cold water
> pipe is no longer sufficient for earthing.
>
> Article 250.81(a) somehow proves "many links you have put up in
> other threads and none of them has agreed with you"? It somehow
> defines surge protection?
>
> Accurately posted: A protector is only as effective as its earth
> ground. No earth ground means no effective protection. After all, how
> does a protector "divert" to earth when not connected to earth? My
> many citations repeatedly discuss THE most critical component in any
> protection 'system': earthing.
>
> And NEC is quite specific: cold water pipe is no longer sufficient
> for a building's earthing electrode.
>
> Bud-- wrote:
>
w_tom
Yes or no did you repeatedly state that connections to water pipes are
only for removing electricity? Remember only a yes or no answer is
acceptable! Any other answer is a duck and dodge.
--
Tom Horne
"This alternating current stuff is just a fad. It is much too dangerous
for general use." Thomas Alva Edison
| |
|
| w_tom wrote:
> Bud claimed:
>
>
> As was noted back then, household electronic appliances are also
> connections to antenna like devices - called AC electric and telephone
> utility wires. To lightning, utiliity wires are no different than a
> radio station antenna. Those Polyphaser app notes on radio
> transmitters and other facilities (yes, Polyphaser discusses more than
> radio transmitters) such as telephone communication equipment all
> describe same protection techniques required for household PC, portable
> phone base station, television, etc. Protection so well proven for
> radio stations is installed in homes to make direct lightning strikes
> mostly irrelevant.
>
Antenna towers are likely to take a direct lightning strike resulting in
huge currents. A house is not exposed to anything vaguely resembling
that over its power/signal lines, nor to the effects from direct
induction. I remember no post to any thread that thought a house could
be protected from a near strike on a power line. You would have to
explain how tower protection is relevant to a house. But don't bother -
see next point.
> No science paper will provide a sound byte if seeking a direct quote.
> Science papers stick to specific science points - concepts. Sound byte
> is obvious from those concepts, Some consumers (such as nickravo)
> asked for science dumbed down to a sound byte. What is the most
> critical component in every protection system? Single point earth
> ground. "Protection system is only as effective as its earth ground".
> What is effective ground? Defined in terms of equipotential,
> conductivity, and how connections are made to that earthing 'system'.
> A sound byte summary are concepts dumbed down to ony a few words.
> Understand the concepts and that sound byte is obvious.
>
"A protector is only as effective as its earth ground. No earth ground
means no effective protection." This seems to be very basic. If true it
should be easy to find support the basic science, the concepts. I asked
for a single specific paper at Phaser that is relevant. You seem to have
forgotten.
<snip - Martzloff, Mansoor ,et al>
Regarding Dr. Mansoor I deferr to Charles Perry:
"I found it particularly funny that he mentioned a paper by Dr. Mansoor.
I can assure you that he supports the use of suge equilization type
plug-in protectors. Heck, he just sits down the hall from me. LOL."
Regarding Martzloff and others - sorry but I want to read what they say,
and in context. Got a link?
> I cited back on 6 Mar from:
> http://www.epri-peac.com/tutorials/sol01tut.html
Wow - an actual link. Oh - rats, what I get is:
"Effective January 1, 2005, EPRI PEAC has been merged into EPRI
Solutions, Inc., a subsidiary of the Electric Power Research Institute
(EPRI).
You will automatically be redirected to www.eprisolutions.com in 10
seconds."
Maybe you could refind it.
> I never provided that www.nist.gov citation. However what does
> that link also state?
>
>
> Funny. That is what I was saying repeatedlywith supporting citations
> That is what the sound byte says.
>
> So which protectors have that necessary ground connection? Well
> that www.nist.gov brochure does not even discuss the most critical
> part of a protecton 'system' - earth ground. Which protector can
> "divert it to ground where it can do no harm"? Never mentioned.
> Reader must somehow discover which protector has no low impedance
> earthing connection. Somehow a plug-in protector will divert to an
> earth ground that all but does not exist? I would
> never cite this url. It is too vague.
Sorry, that one came from Perry. However it does advocate plug-in
point-of-use surge suppressors. NIST believes they provide protection.
And you did supply the link
http://www.keison.co.uk/bowthorpe/d...ion%20Guide.pdf
It also advocates plug-in point-of-use surge suppressors. We both agree
the resistance to earth is likey high for these devices. If they work
then clamping to a common point is effective and ["A protector is only
as effective as its earth ground. No earth ground means no effective
protecction."] is not true.
>
> Meanwhile in that 6 Mar discussion were what - maybe 30 other
> citations that also demonstrate effective protection, earthing, and
> personal testimony as to why earthing is so effective. Bud says none
> of my citations do so. Even the Polyphaser citation - highly regarded
> by industry professionals - demonstrates the concept. A concept that
> applies to radio stations as well as household - two port - appliances.
>
None of them I read did. But I am so happy. Because it will be easy for
you to provide one or two reputable links that clearly support "A
protector is only as effective as its earth ground. No earth ground
means no effective protection." Hey - didn't I ask for links in my last
post? Did you forget?
Kindly don't supply 30. I don't have the time and have become disillusioned.
Oh, personal testimony endorses astrology and even more bizare beliefs.
Something scientific would be nice.
>
> Bud-- wrote:
>
>
>
| |
|
| w_tom wrote:
.......
>
> A is earthing via a cold water pipe. B & C are other 'supplemental'
> earthing electrodes. B or C are sufficient to meet code. A - a water
> pipe earth ground is not sufficient as an only earthing electrode.
> This in direct contradiction to what Bud has posted:
>
>
>
> First, Article 250.81(a) has been removed from code. NEC Article
> 250.52(A) lists seven earthing electrodes that are legal. Only one is
> insufficient. Only one that can be added to a earthing system but is
> not sufficient is the cold water pipe. To put that quoted sentence in
> proper context - "Water pipe is no longer acceptable as an only
> earthing electrode." I posted accurately and quoted code: Article
> 250.53(D)(2).
>
Article 250 of the NEC was extensively reorganized in 1999.
2005-250.52-A-1 is the direct descendant of 1999-250-81-a. All comments
about being removed/obsolete are wrong. And water pipe "can be added" is
wrong - it "must" be added (if 10 ft...).
Many people have contested your water pipe posts. We are quite aware
that a supplemental electrode is required. It is very unlikely anyone
would challenge "water pipe is no longer acceptable as an only earthing
electrode" from this post. But "water pipe is no longer acceptable as an
earth ground", from previous post, has a different meaning.
> Post 2000 code does not (anywhere I can find) even discuss plastic
> pipe. Many reasons besides plastic pipe for why cold water pipe is not
> sufficient as an earthing ground.
>
Many reasons? Name several.
--------------------
From your (w-tom) posts in a recent thread [with my comments]
"Water pipe must be bonded to AC electric for human safety
reasons. The only electrical connection acceptable to pipes
are connections that remove electricity. This for many
reasons including future use of plastic pipe and plumber
safety. No longer acceptable to wire electrical devices to
water pipes with intent of making that water pipe a safety
ground. Electric wire connections to water pipes are
permitted only to remove dangerous electric currents from
those pipes."
[Appears to me to say a water pipe may not be used as a grounding
electrode. Also, with the grounding electrode conductor attached within
5 ft of the entrance and the meter bonded, there is a hazard to a
plumber? And I never have figured out what "remove electricity" is.]
"What some non-electricians are having a problem with are other
electrical and electronic reasons why a water pipe ground is
not sufficient. Involves parameters that concern engineers -
that include and go beyond an electrician's code requirements.
Remember, code is only about human safety. But the earthing system also
performs other functions - such as transistor safety."
[You are arguing that a ground rod provides superior earthing to a water
pipe. Ground rods (and plates) are the only electrodes that must have
their ground resistance measured (25 ohms is "good") - unless 2 rods are
installed, then ground resistance can be over 25 ohms. I have seen
stated typical ground resistance values of 3 ohms for municipial water
systems. But ground rods are better?]
Two reasons why water pipe earthing is no longer sufficient. NEC
requires water pipe be bonded to AC electric safety ground -
for human safety reasons. NEC requires other electrodes (2
through 7) for earthing.
[Appears again to say a water pipe may not be used as a grounding
electrode.]
>
> Article 250.81(a) somehow proves "many links you have put up in
> other threads and none of them has agreed with you"? It somehow
> defines surge protection?
>
This should have been an independent point - I thought of that after
posting.
bud--
| |
| w_tom 2006-04-14, 11:21 pm |
| Bud-- wrote:
> This should have been an independent point - I thought of that after
> posting.
Yes, 'structure earthing' is a topic different from the original
surge protector and surge protection question. But it does have a
distant relationship since earthing also defines whether a surge
protector is effective. That relationship dicussed later.
Article 250.81(a) began a series of changes in building earthing - in
what is considered sufficient. Originally a building (home) used water
pipe bonding for two purposes:
Point First: to remove electriticy from pipes so that a human could
not be electrocuted. Other items might be bonded to those pipes (ie
telephone line) because water pipes were considered a good safety
ground.
Point Second: breaker box was bonded to water pipes as an only
electrical earth ground. Code considered water pipes as a low
resistance and reliable earthing.
Along comes plastic replacement pipe. Code also began considering
safety of plumbers who, while standing in water, might disconnect a
pipe and be electrically shocked (right there are two of 'many'
reasons). Code changed. Any grounding for human safety must use
devices dedicated only for that electrical purpose (reliablity -
another reason). Water pipes are not intended primarily for electrical
earthing - therefore water pipes are no longer sufficient for earthing.
Water pipes are not intended primarily for electrical bonding -
therefore anything that must be bonded cannot use (connect to) water
pipes for that human safety ground function. In short, any connection
to pipe must be only to remove electricity - not dump electricity into
a pipe
Safety cannot be obtained by dumping electricity into pipes for many
reasons including the most obvious - plastic pipes.
We still meet the original purpose of above Point First. We bond -
a connection from cold water pipe to breaker box safety ground - to
remove electricity from pipes. We cannot make any electrical
connection to pipes anywhere in the building to dump electricity into
those pipes as was once considered acceptable. And we bond to remove
electricity from those pipes.
From Mike Holt at:
http://www.mikeholt.com/files/PDF/L...sion_May051.pdf
> The NEC (Art. 250.52) also disallows almost all use of water pipes
> as a ground for protectors or other equipment. The extensive use
> of plastic piping and water meters, possible corrosion, and the
> likelihood of later plumbing modifications make it unreliable to use
> pipes as ground electrodes. ...
Point Second: 'earthing a building' again says that water pipe is no
longer sufficient for earth ground - use of plastic pipe is only one
reason why. Code lists six other earthing electrodes that are
acceptable. So why is cold water pipe still on that electrode list?
If cold water pipe was removed from the list, then cold water pipe must
include an electrical isolator between interior water pipes and buried
pipes - similar to what is often found on some natural gas pipes. That
isolator would be rediculous - counterproductive. So we don't
completely ban cold water pipes as an earth ground. We make the
electrical isolator unnecessary by saying water pipes are earthed; but
are not sufficient for earthing. Cold water pipes no longer provide
earthing requrired by code - they are not sufficient.
We don't demand an electrical isolator between undergound and
interiior pipes. But cold water pipes (in most cases) are no longer
sufficient for earthing as demonstrated by previous quotes from the NEC
and even the above Mike Holt explanation. Since 1990, electrical
service must have some other earthing solution AND that earthing
solution must be close to every incoming utility. That's right. Code
states distance to earth ground even for cable TV and telephone.
Above defines earthing and bonding only for human safety. Now we go
one step farther - earthing for transistor safety. Code does not
consider transistor safety except where those transistors might
threaten human life. But we humans also need transistor safety. And
code is written to make that protection easier. For transistor safety,
we need a short, direct and independent connection from each incoming
utility to a single point earth ground. Reasons why are beyond the
code and often are not understood by electricians. Code only addresses
human safety issues; not transistor safety issues.
Some utilities, such as coax cable, require no surge protector to
have surge protection. That coax cable connects directly (hardwired)
to a dedicated earth ground. Other utilities (telephone and AC
electric) require a short earthing connection via surge protectors. We
now have a relationship between earth ground and our main topic - surge
protectors. We now have but another reason for a dedicated earth
ground. Remember, I said there were many reasons - not just plastic
pipe.
As noted so many times previously, a surge protector only *diverts* a
surge to earth ground. Surge protectors provide no protection.
Protector is simply an electrical connection device - similar in
function to a switch. Protector connects surge protection to each wire
inside each utility cable.
Too often, cold water pipe is too far away to perform earthing. But
again, a distant cold water pipe is not sufficient for earthing.
Earthing connections must be less than 10 feet for transistor safety.
Just another reason why a building uses any one of those other six
earthing electrodes defined by National Electrical Code (NEC).
Superior earthing provided by Ufer or halo grounds - if we really
addressed transistor safety.
Cold water pipe grounding once served two functions - bonding (remove
electricity from water pipes) and earthing (connect breaker box to
earth ground). Point First function remains as it did 30+ years ago.
Point Second function is now located elsewhere. A third and recent
function - surge protection - typically requires earthing not
sufficiently provided by cold water pipes.
Of course many people contest my posts - as described above. I would
not post if others were not posting half truths, misguided assumptions,
wlld speculation, or just confused. I have no interest posting where
the informed are posting accurately. I post where myths are common.
Notice that Tom Horne's reply was intended to be confrontational - not
provide useful facts. For that matter, Saddam clearly has weapons of
mass destruction because well over 70%believed it. I didn't. I first
read those reports from advanced physics labs and other sources; where
facts and numbers rather than speculation were provided. But I must
have been wrong because 70% said otherwise. Number of who disagree
means nothing. Otherwise Saddam has WMDs. You don't care about how
many disagree. You worry about underlying facts and numbers. Provided
are many facts and even a quote from the NEC as to why cold water pipe
is no longer sufficient for earthing.
Code is written (Article 250.52) so that an electrical isolator need
not be put on cold water pipes. We earth for numerous reasons.
Reasons that also make a surge protector effective. Cold water pipe is
no longer sufficient for earthing.
Meanwhile, the sound byte: a surge protector is only as effective as
its earth ground. From above, earth ground is more complex and more
important than most realize.
Bud-- wrote:
>
> Article 250 of the NEC was extensively reorganized in 1999.
> 2005-250.52-A-1 is the direct descendant of 1999-250-81-a. All comments
> about being removed/obsolete are wrong. And water pipe "can be added" is
> wrong - it "must" be added (if 10 ft...).
>
> Many people have contested your water pipe posts. We are quite aware
> that a supplemental electrode is required. It is very unlikely anyone
> would challenge "water pipe is no longer acceptable as an only earthing
> electrode" from this post. But "water pipe is no longer acceptable as an
> earth ground", from previous post, has a different meaning.
> ...
>
>
> Many reasons? Name several.
| |
|
| w_tom wrote:
>
> As noted so many times previously, a surge protector only *diverts* a
> surge to earth ground.
You *still* don't understand that energy will be absorbed &
dissipated when current flows through a resistance?
P = I^2 * R
where P is the power dissipated in the resistance of the
protector, I is the current through the protector, and R
is its resistance.
QED - the protector will dissipate surge energy.
To say it will only divert a surge is blatantly wrong.
You cannot get around the laws of physics, no matter
how often you post that incorrect idea.
The remaining points below in your post, predicated
on that misconception, are wrong.
Ed
| |
|
| Because "energy will be absorbed & dissipated when current flows
through a resistance" then the purpose of wire is to absorb and
dissipate electrical energy. Surge protectors, like wire, will
dissipate some energy when performing their function: to conduct,
shunt, divert, transport that electricity. Shunt mode protectors do
not to suppress, absorb, dissipate, or arrest energy as ehsjr
repeatedly claims over so many years. Although some energy is
dissipated (neither wire nor protectors are perfect conductors), well,
a one hundred joule protector will absorb how many joules in a
lightning strike? (One joule is one volt and one amp for one second:
how many in lightning?) How many joules will that 100 joule protector
suppress, absord, or arrest?
A wire diverts (conducts) energy to my vacuum cleaner. How many
joules has its power cord suppressed, absorbed, dissipated, or
arrested? About 3700 joules. Well that proves it. The purpose of a
power cord is to absorb electricity. Meanwhile the power cord carries
another 3,456,000 joules into the vacuum cleaner. Irrelevant. That
wire dissipated / absorbed energy. Absorbing enery must be its
purpose.
When ehsjr posts this same refrain, a credible source is cited in
reply. This time the National Institute of Science and Technology is
quoted from in their publication 960-6 entitled "Surges Happen! How to
Protect the Appliances in your Home.":
> You cannot really suppress a surge, altogether, nor "arrest"
> it. What these protective devices do is neither suppress nor
> arrest as urge, but simply divert it to ground, where it can do
> no harm. So a name that makes sense would be a "surge
> diverter"
ehsjr wrote:
> You *still* don't understand that energy will be absorbed &
> dissipated when current flows through a resistance?
> P = I^2 * R
> where P is the power dissipated in the resistance of the
> protector, I is the current through the protector, and R
> is its resistance.
> QED - the protector will dissipate surge energy.
>
> To say it will only divert a surge is blatantly wrong.
> You cannot get around the laws of physics, no matter
> how often you post that incorrect idea.
>
> The remaining points below in your post, predicated
> on that misconception, are wrong.
| |
|
| w_tom wrote:
You clipped your innacurate statement that is the bone
of contention:
" As noted so many times previously, a surge protector
only *diverts* a surge to earth ground."
Your second sentence below admits that surge protectors
will dissipate some energy. Congratulations! But then
you contradict yourself in the next sentence, saying
"shunt mode protectors do not suppress, absorb, dissipate ..."
> Because "energy will be absorbed & dissipated when current flows
> through a resistance" then the purpose of wire is to absorb and
> dissipate electrical energy. Surge protectors, like wire, will
> dissipate some energy when performing their function: to conduct,
> shunt, divert, transport that electricity. Shunt mode protectors do
> not to suppress, absorb, dissipate, or arrest energy as ehsjr
> repeatedly claims over so many years. Although some energy is
> dissipated (neither wire nor protectors are perfect conductors), well,
> a one hundred joule protector will absorb how many joules in a
> lightning strike? (One joule is one volt and one amp for one second:
> how many in lightning?) How many joules will that 100 joule protector
> suppress, absord, or arrest?
You mention what you call a credible source. Here's what
it says to that question:
"Joules -A (simplified) measure of the surge energy that the protector
can dissipate without damage to itself. The higher the value, the more
energy the protector can handle. Typical values range from about 100
joules, up to 1000 joules or more. Because this joule number is often
based on the three combinations of the wiring, many specifications show
the total joules rather than a breakdown among each of the three
combinations. Maximum surge current (below) may give better information."
http://www.pueblo.gsa.gov/cic_text/...g/surge/q-a.htm
To answer the question you posed about how many joules will
a 100 joule protector absorb in a lightning strike: up to
100 joules. Obviously, if less than that amount reaches the
protector, it won't absorb the full 100 joules. If more than
100 reaches the supressor, the energy it absorbs will burn
it out.
>
> A wire diverts (conducts) energy to my vacuum cleaner. How many
> joules has its power cord suppressed, absorbed, dissipated, or
> arrested? About 3700 joules. Well that proves it. The purpose of a
> power cord is to absorb electricity. Meanwhile the power cord carries
> another 3,456,000 joules into the vacuum cleaner. Irrelevant. That
> wire dissipated / absorbed energy. Absorbing enery must be its
> purpose.
Your comparison is ridiculous. The valid comparison is of the MOV
to the vacuum cleaner, not to its cord. Just look:
-------
-------------|Vacuum |
-------------|Cleaner|
-------
---
-------------|MOV|
-------------| |
---
>
> When ehsjr posts this same refrain, a credible source is cited in
> reply. This time the National Institute of Science and Technology is
> quoted from in their publication 960-6 entitled "Surges Happen! How to
> Protect the Appliances in your Home.":
>
>
The document you mention can be found here:
http://www.pueblo.gsa.gov/cic_text/...surge/surge.htm
Click on "Protection at the Outlet" to see the material quoted
below, or go there directly using this link:
http://www.pueblo.gsa.gov/cic_text/...e/what-kind.htm
Here's what the credible source says regarding point of use
protectors:
"Examples of one-link connection of powered electronic appliances
include a TV set with "rabbit ears" antenna, a portable radio receiver,
a computer with no modem connection or remote printer, a compact
fluorescent lamp, etc. In the category of one-link connection we also
find an old-fashioned telephone connected only to the telephone system.
Note that most of these have a two-prong plug, which is their sole
connection to the power system. For the TV set, a simple" AC plug-in
surge protector on the power cord would be sufficient." ...
"A simple solution to the problem of voltage differences for two-link
appliances is to install a special surge protector that incorporates, in
the same package, a combination of input/output connections for the two
systems. Each link, power and communications, is fed through the
protector which is then inserted between the wall receptacles and the
input of the appliance to be protected. This type of surge protector is
readily available in computer and electronics stores, and the electrical
section of home building stores."
Your source denies your mantra that point of use protectors
are no good or offer no protection or whatever variation.
The source is credible according to you. You picked it, I
did not. Polyphaser, which you often cite, sells point
of use protectors, which again opposes your position. Your
physics is wrong, your example is pure smokescreen. You have
admitted that point of use protectors absorb energy - you have
even posted pictures dramatically proving that they do.
Your incessant drivel that protectors are not protection,
or that point of use protectors are not effective, or
whatever variation you use serves only to dilute and
discredit some of the excellent points you do make.
It's really simple. Good protection starts with a
good ground system. Relying solely on a point of use
protector is a crap shoot - it might protect your
equipment, and it might not.
Ed
>
> ehsjr wrote:
>
>
>
| |
| w_tom 2006-04-16, 10:21 pm |
| > "How many joules will a 100 joule protector absorb in a lightning strike: up to 100 joules"
Yes - while same MOV typically diverts many thousands of joules to
earth ground. Ed tells us a transient of 101 or 200 joules will
damage a 100 joule MOV. Of course not. ehsjr was provided numbers so
many years ago which he apparently did not understand. A wire also
dissipates joules when it carries thousands more joules elsewhere. My
vacuum cord dissipates 3000 joules while delivering (diverting)
millions of joules to that vacuum cleaner. But since the vacuum wire
does not degrade with use, then we don't rate that wire in joules. We
rate MOVs in joules because MOVs degrade (not burn out - degrades)
when acting like a wire.
MOV life expectancy is measured in joules. Posted so many times
previously to ehsjr - who ignores numbers he apparently cannot
understand. A 40 joule MOV (2V130) dissipated 0.6 watts during what?
A 25,000 watt transient. So what happened to the other 24999.4 watts?
ehsjr forgets those numbers from 5 years ago. Some silly idea that an
MOV absorbs near 100% of a transient.
Yes, a 100 joule MOV can dissipate 100 joules or more (depending on
other transient parameters) - while MOV diverts many thousands of
joules to ground. Again, a protector is only as effective as its earth
ground - where the transient is dissipated. Ed simply spins a half
truth into some idea that a 100 joule transient will be dissipated by a
100 joule MOV. Somehow his myth: a plug-in protector located between a
TV and a power receptacle will absorb a direct lightning strike. It
will stop what three miles of sky could not. Total nonsense used to
promote ineffective plug-in protectors. When properly installed, a
protector diverts a transient to earth ground.
Ignoring repeated spin that Ed has posted over so many years - and
moving on to numbers provided by MOV manufacturers. As the number of
MOV joules increases, then number of transient joules dissipated in
earth ground increases exponentially.
MOV joules from manufacturer charts estimate MOV life expectancy.
MOV manufacturers provide charts for MOV joules verses transient
current verses impulse time verses number of transients. MOV joules
measures an MOV life expectancy which is a number different from many
times more joules that are diverted.
MOV dissipates energy - as a wire does. When an MOV - or a wire -
dissipated 100 joules, many times more energy is dissipated elsewhere.
ehsjr tells us the purpose of that wire or MOV is to absorb all
transient's energy. He uses junk scientist reasoning. Notice he
provides no numbers from manufacturer datasheets.
A 10000 volt 100 amp impulse of maybe 14 joules arrives at an earthed
MOV. According to Ed, almost all of up to 1000000 watts are dissipated
in that MOV. Not true for one minute. MOV with a threshold voltage of
200 volts dissipates maybe 0.3 joules. Where is the rest of that
energy dissipated? In this example, diverted to earth ground is well
over 90% of the energy. Notice why a protector is only as effective as
its earth ground. Notice where the energy is dumped - dissipated.
Why do we rate MOVs in joules? Suppose that MOV is rated at 2
joules. Manufacturer life expectancy chart says it will divert 10
identical transients before degrading (not vaporizing or 'burned out'
which is unacceptable for MOVs). If that MOV increases to 5 joules,
then chart estimates degradation after 500 transients. 500 transients
at 0.3 joules - about 150 joules dissipated by a 5 joule MOV. 10
transients by a 2 joule MOV - 3 joules dissipated when MOV has
degraded. An MOV that is 2.5 times larger has a life expectancy 50
times larger. Welcome to what MOV joules measures - life expectancy.
Notice the emotion that ehsjr posts:
Some cannot post facts and numbers. So they insult. That sentence
demonstrates his frustration. Above are numbers from an MOV
manufacturer datasheet. ehsjr is posting half accurate facts. Ed
forgets to provide a whole story. Why? If the purpose of a protector
is to divert to earth, then the plug-in protectors are not effective.
Which plug-in protector company or reseller does Ed work for?
Yes MOV dissipates energy - just like a vacuum cleaner power cord
dissipated energy. Using ehsjr half truths, then purpose of that power
cord is to dissipate energy. Meanwhile the purpose of a shunt mode
protector is to *divert* that energy to earth ground - as Franklin
lightning rods also do. Ground: what plug-in protectors avoid to
promote their ineffective products. A protector is only as effective
as its earth ground.
If a power cord had a life expectancy, it too would be rated in
joules. But joules - to measure MOV life expectancy - are not the
number of transient joules diverted as Ed would proclaim. An effective
shunt mode protector *diverts* - no matter how many times I get
insulted by ehsjr.
Meanwhile another industry professional - Sun Microsystem from their
Planning guide for Sun Server room Section 5.4.7 Lightning
Protection (Adobe page 89):
http://www.sun.com/servers/white-pa...nning-guide.pdf[color=darkred]
> Lightning surges cannot be stopped, but they can be diverted. The plans
> for the data center should be thoroughly reviewed to identify any paths
> for surge entry into the data center. Surge arrestors can be designed
> into the system to help mitigate the potential for lightning damage within
> the data center. These should divert the power of the surge by providing
> a path to ground for the surge energy.
To sell ineffective plug-in protectors, many ignore what protectors
do? ehsjr instead makes claims using half truths - and has been doing
so for years. And then he does what he has done for years - insult.
Provided are numbers for MOV manfacturers - and as usual - a citation
from another responsible source that contradicts what ehsjr posts.
Strange how ehsjr repeatedly posts half truths promoted by the plug-in
protector manufacturers - who also don't provide numbers.
ehsjr wrote:
> To answer the question you posed about how many joules will
> a 100 joule protector absorb in a lightning strike: up to
> 100 joules. Obviously, if less than that amount reaches the
> protector, it won't absorb the full 100 joules. If more than
> 100 reaches the supressor, the energy it absorbs will burn
> it out.
> ...
>
>
> Your incessant drivel that protectors are not protection,
> or that point of use protectors are not effective, or
> whatever variation you use serves only to dilute and
> discredit some of the excellent points you do make.
> It's really simple. Good protection starts with a
> good ground system. Relying solely on a point of use
> protector is a crap shoot - it might protect your
> equipment, and it might not.
>
> Ed
| |
|
| w_tom wrote:
>
>
You previously stated:
"As noted so many times previously, a surge protector only *diverts* a
surge to earth ground."
Now you have recognized and stated that an MOV style protector
*absorbs* energy.
Therefore, you cannot truthfully maintain your position that
point of use surge protectors are not effective, or are usless
or that they provide no protection or whatever way you put it.
The degree of effectivness is a completely different matter.
A point of use protector can be overwhelmed, as can a whole
house protector, if energy in excess of what they can absorb
appears at their terminals. But until the surge kills them,
whatever surge energy does appear at their terminals, they
absorb, in accordance with ohm's law. You can't get around
P = I^2R where R is the resistance of the MOV and I is the
current through it.
Talking of the energy in a lightning strike is pointless.
What matters is the energy that arrives at the MOV's
leads. Provided it is sufficient to cause the MOV to
go into clamping mode, the MOV will attempt to absorb
the energy at its leads, or die trying.
> Yes - while same MOV typically diverts many thousands of joules to
> earth ground. Ed tells us a transient of 101 or 200 joules will
> damage a 100 joule MOV. Of course not. ehsjr was provided numbers so
> many years ago which he apparently did not understand. A wire also
> dissipates joules when it carries thousands more joules elsewhere. My
> vacuum cord dissipates 3000 joules while delivering (diverting)
> millions of joules to that vacuum cleaner. But since the vacuum wire
> does not degrade with use, then we don't rate that wire in joules. We
> rate MOVs in joules because MOVs degrade (not burn out - degrades)
> when acting like a wire.
Are you really so desparate to attempt to support your position
that you compare a wire in series with a load, to an MOV which
is in parallel with the load?
The wire you mentioned is in series with the vacuum cleaner.
The MOV point of use supressor is in parallel with the device
plugged into it.
If you make the proper analogy, the wire you are talking
about would have to be placed in parallel with the
vacuum cleaner. And it would vaporize, long before millions
of joules reached your vacuum cleaner.
Your lack of understanding of a series vs a parallel circuit
explains why you think as you do on this subject.
With something that glaringly wrong, the rest of your post
is not worth a response.
Ed
| |
|
| w_tom wrote:
> Originally a building (home) used water
> pipe bonding for two purposes:
>
> Point First: to remove electriticy from pipes so that a human could
> not be electrocuted. Other items might be bonded to those pipes (ie
> telephone line) because water pipes were considered a good safety
> ground.
>
It would be nice, particularly in an engineering forum, if you could
find a clear unambiguous description to replace "remove electriticy from
pipes".
> Point Second: breaker box was bonded to water pipes as an only
> electrical earth ground. Code considered water pipes as a low
> resistance and reliable earthing.
>
> Along comes plastic replacement pipe. Code also began considering
> safety of plumbers who, while standing in water, might disconnect a
> pipe and be electrically shocked (right there are two of 'many'
> reasons). Code changed. Any grounding for human safety must use
> devices dedicated only for that electrical purpose (reliablity -
> another reason). Water pipes are not intended primarily for electrical
> earthing - therefore water pipes are no longer sufficient for earthing.
> Water pipes are not intended primarily for electrical bonding -
> therefore anything that must be bonded cannot use (connect to) water
> pipes for that human safety ground function. In short, any connection
> to pipe must be only to remove electricity - not dump electricity into
> a pipe
>
"Dedicated only for that electrical purpose"? You are also excluding
structural metal framework, and Ufer grounds. Of the 6 electrodes
required to be included, if present, only water pipe and structural
framework are required to have grounding electrode conductors (GEC)
increase in size as the service size is increased. Ufer does not have to
be larger than #4 and rods/plates does not have to be larger than #6. It
would seem the NEC views water pipe and structural steel as an effective
electrodes, with a greater grounding capacity that other electrodes.
You said there were "many reasons besides plastic pipe for why cold
water pipe is not sufficient as an earthing ground." You give here:
Plumber safety. Cite a source. And since a water pipe is still required
to be a grounding electrode how is this a reason.
One? = "many"?
[By water pipes I mean burried >10 ft.... and especially municipal metal
water pipe systems.]
> Safety cannot be obtained by dumping electricity into pipes for many
> reasons including the most obvious - plastic pipes.
>
> We still meet the original purpose of above Point First. We bond -
> a connection from cold water pipe to breaker box safety ground - to
> remove electricity from pipes. We cannot make any electrical
> connection to pipes anywhere in the building to dump electricity into
> those pipes as was once considered acceptable. And we bond to remove
> electricity from those pipes.
>
If intended only for bonding, the NEC required bonding conductor would
be much smaller than the GEC that is actually required.
> From Mike Holt at:
> http://www.mikeholt.com/files/PDF/L...sion_May051.pdf
>
>
The link is actually a IEEE document, "How to protect hour house and its
contents from lightning" probably of great interest to any one still on
this thread, very good - good post. I presume this quote is that
connections cannot be made directly to a water pipe for communications
protectors or other earthing or bonding purposes (although, IIRC, they
can be made within 5' of the entrance). I presume it is not saying water
pipes can't be used as a ground electrode because the NEC requires them
to be used as a grounding electrode.
From page 7:"The NEC/CEC requirements for connecting all metal piping
and large metal parts of the structure to the building ground serve two
purposes: If there is metallic buried water piping, bonding it to the
building ground improves the quality of that ground. Also, in the rare
event of a direct strike to the piping, or to a metallic part of the
structure, the ground bond conducts the lightning currents safely into
the building ground."
>
> Point Second: 'earthing a building' again says that water pipe is no
> longer sufficient for earth ground - use of plastic pipe is only one
> reason why. Code lists six other earthing electrodes that are
> acceptable. So why is cold water pipe still on that electrode list?
> If cold water pipe was removed from the list, then cold water pipe must
> include an electrical isolator between interior water pipes and buried
> pipes - similar to what is often found on some natural gas pipes. That
> isolator would be rediculous - counterproductive. So we don't
> completely ban cold water pipes as an earth ground. We make the
> electrical isolator unnecessary by saying water pipes are earthed; but
> are not sufficient for earthing. Cold water pipes no longer provide
> earthing requrired by code - they are not sufficient.
>
Cite a source that agrees with your isolator argument.
>
> Some utilities, such as coax cable, require no surge protector to
> have surge protection. That coax cable connects directly (hardwired)
> to a dedicated earth ground. Other utilities (telephone and AC
> electric) require a short earthing connection via surge protectors. We
> now have a relationship between earth ground and our main topic - surge
> protectors. We now have but another reason for a dedicated earth
> ground. Remember, I said there were many reasons - not just plastic
> pipe.
>
I'm not aware any signal utilities required a dedicated earthing. In any
case the NEC requires all earthing to be tied together into one system.
And we both believe in single point ground where power
neutral-ground/bond connection and signal protector earthing connection
are tied with minimal length and earthed together. Dedicated earth ground??
> As noted so many times previously, a surge protector only *diverts* a
> surge to earth ground. Surge protectors provide no protection.
> Protector is simply an electrical connection device - similar in
> function to a switch. Protector connects surge protection to each wire
> inside each utility cable.
>
In your excelent Holt/IEEE post, Fig 7 illustrates a TV protected by a
plug-in point-of-use multi-port surge suppressor. The illustration has a
cable ground block remote from the electrical service and attached to it
by a ground wire. The cable has a lighting strike and the ground current
lifts the cable ground block 10kV above the service panel. At the TV the
cable is at 10kV with respect to the TV, not recommended. With a
multi-port suppressor installed, at the suppressor (at the TV) the cable
ground is connected to the power ground. These points thus will be at
the same voltage although that voltage will be thousands of volts
different from the electrical service and the cable ground block. Since
the surge suppressor clamps hot, neutral, and cable center conductor to
that local reference ground the TV is not damaged although it is at
thousands of volts above ‘absolute' ground. The TV has not been
protected by diverting the surge to ground but by clamping all wires to
a common reference point.
This illustrates protection primarily by clamping action, not diversion
to ground - common to plug-in suppressors. Plug-in suppressors are
strongly supported by this - your - link. Also by another of your links
and the NIST in a previous post.
In the meantime you have not furnished one or two links that clearly
demonstrate that "only" diversion works. Musta forgot again
>
> Of course many people contest my posts - as described above. I would
> not post if others were not posting half truths, misguided assumptions,
> wlld speculation, or just confused. I have no interest posting where
> the informed are posting accurately. I post where myths are common.
> Notice that Tom Horne's reply was intended to be confrontational - not
> provide useful facts. For that matter, Saddam clearly has weapons of
> mass destruction because well over 70%believed it. I didn't. I first
> read those reports from advanced physics labs and other sources; where
> facts and numbers rather than speculation were provided. But I must
> have been wrong because 70% said otherwise. Number of who disagree
> means nothing. Otherwise Saddam has WMDs. You don't care about how
> many disagree. You worry about underlying facts and numbers. Provided
> are many facts and even a quote from the NEC as to why cold water pipe
> is no longer sufficient for earthing.
>
In your case it seems to be 100% to 0%.
Hmm - I'm right and everyone else is wrong - sounds like paranoid
schizophrenia.
Of course there are numerous reputable links - "facts and numbers" -
supporting your views - you just forgot to include them - again.
bud--
| |
|
| Purpose of connecting (bonding) breaker box safety ground to water
pipes is to 'remove electricity'. Yes, that is it not technically
explicit. Yes, there are exceptions. Should I post a thesis on this -
or did you read code for further details? Where is that purpose
incorrect? No, the code does not explicity define the purpose. But
what it demands is repeated and even summarized by Mike Holt.
Connecting to pipes to safety ground a device - to 'dump electricity
into those pipes' - is no longer acceptable.
Telephone line, once grounded anywhere inside building to cold water
pipes (as was so common in the 1960s), is no longer acceptable. Cable
TV wire cannot be 'earthed' to outside water faucet. Telephone ground
can no longer be made to pipes as was standard in the 1960s. We
connect wires to pipes only to 'remove electricity'. And not just
electricity that might short to interior pipes. We also must
'intercept' a current that may be coming from outside mains. Cold
water pipe must be bonded where it enters building - required by code
for human safety. Electricity must be removed from pipes.
I need not cite sources for plumber protection. We have changed the
code whereever plumbers would be at risk. A ground wire must bypass
water meter so that plumber need not fear things electrical. A bypass
ground must connect hot pipe to cold pipe so that hot pipes are safety
grounded AND so that a plumber is not at risk if changing that hot
water heater. We bond for human safety so that even a plumber standing
in water need not be harmed when disconnecting a pipe and need not have
electrician's knowledge. Review of code will demonstarte many new
requirements that now protect the plumber - which was long overdue.
Structural metal work or Ufer ground: why do you misrepresent what
NEC demands? NEC defines the acceptable (and sufficient) six earthing
electrodes. Other earthing electrodes are not permitted. If cold
water pipe was not a seventh item in the list, then code water pipe
would require electrical isolation. The list is specific; what is only
permitted for earthing. Structural metal work and Ufer ground are
listed in Article 250.52(A) making your question puzzling. Did you
read the code; a list of what is acceptable for earthing?
Cold water pipe is specifically listed as not sufficient in Article
250.53(D)(2). Code lists what is only acceptable as an earthing
electrode - including Ufer ground, et al - AND code states that cold
water pipe is not sufficient for earthing.
You posted:
> You are also excluding structural metal framework, and Ufer grounds
You could only post this is you did not read Article 250.52(A).
Why is cold water pipe still listed as an earthing electrode?
Because if cold water pipe is not an earth ground, then cold water pipe
connected to breaker box must be electrically isolated from earthing.
Code is specific what can and cannot be an earthing electrode. Cold
water pipe can make a connection to earth ground BUT cold water pipe is
no longer sufficient as the ONLY earth ground (exceptions exist that
are well beyond the scope of this discussion).
#4 AWG is sufficient for earthing. Anything to improve that earthing
is totally irrelevant to code and irrelevant to whether cold water pipe
is sufficient to earthing. Why do you disparage #4 AWG wire because
water pipe has a larger diameter? Water pipe with a larger diameter
makes the #4 AWG wire insufficient? Nonsense. Irrelevant both to what
code says and what is discussed here.
Furthermore, if we built new homes for transistor safety, then water
pipe - what you regard as a better earthing electrode - would be an
electrically inferior ground. Transistor protection is defined first
and foremost by earthing. We earth for reasons in code (human safety)
and then we also earth for transistor safety.
Why are you confusing communication ground with electrical ground
(citing Mike Holt quote)? Code wants communication and electrical
earthing to be common. Obviously earthing can become more complex in
industrial environments. But a residential communication and
electrical electrode should always be at same point. Code even states
maximum permissible length for each earthing wire. We also need that
common earthing point for transistor safety - another requirement
beyond scope of code and that defines effectiveness of a protector.
Mike Holt's example of protectors insists that even 'point of use'
protectors be grounded. Why? Protectors earth a transient. What must
it 'clamp' to? Earth ground. IOW 'clamping' is also 'diverting' a
transient to ground. Why do you confuse 'clamping' with 'diverting'?
Mike Holt defines grounding essential which is why I am so mystified
why you have misrepresented 'clamping':
> A substantial fraction of the damage to point-of-use protectors,
> and to equipment, occurs because these ground bonds or primary
> protectors are missing or inadequate. Recurrent damage to
> protectors or equipment in a particular location is almost always a
> sign of a missing or improperly grounded protector.
Goes right back to a protector's purpose. An effective protector
'diverts' transients to earth as so many responsible and previously
cited sources state. Manufactures selling ineffective plug-in
protectors ignore all that hoping you never learn what a protector must
do. An effective protector clamps / diverts a transient to earth
ground.
Obtain appliance protection using 'point of use' protectors to obtain
equipotential - as is discussed by Mike Holt. But be very careful.
Anything that violated equipotential makes a plug-in protector solution
ineffective - as Mike Holt notes. Any one path violating equipotential
and the entire protection is compromised. An appliance wire drapes
down to floor. Equipotential violated. Table electrically connected
to floor or wall. Equipotential violated. Peripheral cable draped
onto adjacent baseboard heater or air duct. Equipotential violated.
Equipotential at the equipment requires a total room-wide analysis.
Like a wooden church steeple, even tables, linoleum tile, and wall
paint must be considered - all may be conductors. Every incoming
electrical connection to an appliance must first make the single point
connection. Good luck accomplishing that inside rooms not constructed
accordingly.
Notice how equipotential and 'point of use' protection gets complex -
and plug-in protector manufacturers avoid this. Mike Holt introduces
requirements for using 'point of use' protectors. Most important, Mike
says a 'whole house' protection system is still required even if using
plug-in protectors.
Let's see. We pay $20 (or $100 for Monster Cable products) per
appliance. How many appliances? 50? Or we spend much less money to
enhance a building's earthing. Enhanced earthing means a transient is
less likely to overwhelm protection already inside an appliance. Did
that plug-in protector manufacturer also forget to mention protection
already exists inside appliances? Curious how many facts that
manufacturer will forget to mention. Previously demonstrated was how a
plug-in protector can even contribute to damage of a powered off
computer - subvert or bypass existing internal protection. Damage
demonstrated by literally tracing the surge and replacing each damaged
IC. A destructive path made possible by an adjacent plug-in protector.
Yes you can attempt equipotential at each appliance, spend massively
more money, and also create these risks:
http://www.ddxg.net/old/surge_protectors.htm
http://www.cob.org/fire/safety/surge.htm
http://www.hanford.gov/rl/?page=556&parent=554
Just another problem associated with plug-in protectors.
'Point of use' protectors can provide some protection ... from
transients that just are not typically destructive. Spend so much more
money and yet not get same protection that can be obtained from
enhancing 'whole house' protection - for tens of times less money.
Not effective also explains why so many plug-in protectors are grossly
undersized. Grossly undersized - the internal MOV vaporized - which is
not an acceptable failure mode. And yet above pictures demonstrate the
problem.
Telephone COs connect to overhead wires everywhere in town. Why is
that telco computer undamaged every year? Telco wants protectors that
connect short to earth and are ideally 50 meters distant from the
computer. Yes, that separation between protector and electronics
enhances protection. Yes a shortest connection to earth enhances
protection. A 'whole house' protector with superior single point earth
ground is more effective - and costs so many times less money. Why
would anyone spend $100 for a Monster Cable product? No separation.
No dedicated and short connection to earth. It does not even claim to
protect from typically destructive transients.
But again, purpose of a protector: made obvious by what an MOV, an
avalanche diode, a spark gap, a gas discharge tube (GDT), and even
telephone line protectors installed on all phone lines 50 years ago -
all do. Each diverts a destructive transient to ground. Each is
'clamped' to an earthing connection. Earthing is the purpose of shunt
mode protectors - divert, clamp, connect, shunt a destructive transient
to earth.
Defined are acceptable earthing electrodes, and the purpose of
earthing. A common earth ground that addresses multiple purposes.
Many pre-1990 buildings may require earthing upgrades / enhancements
for human or transistor safety. A surge protector is only as effective
as its earth ground - which plug-in protector manufacturers hope you
never learn.
Bud-- wrote:
> It would be nice, particularly in an engineering forum, if you could
> find a clear unambiguous description to replace "remove electriticy from
> pipes".
> ...
>
> "Dedicated only for that electrical purpose"? You are also excluding
> structural metal framework, and Ufer grounds. Of the 6 electrodes
> required to be included, if present, only water pipe and structural
> framework are required to have grounding electrode conductors (GEC)
> increase in size as the service size is increased. Ufer does not have to
> be larger than #4 and rods/plates does not have to be larger than #6. It
> would seem the NEC views water pipe and structural steel as an effective
> electrodes, with a greater grounding capacity that other electrodes.
> ...
>
> You said there were "many reasons besides plastic pipe for why cold
> water pipe is not sufficient as an earthing ground." You give here:
> Plumber safety. Cite a source. And since a water pipe is still required
> to be a grounding electrode how is this a reason.
> One? = "many"?
>
> [By water pipes I mean burried >10 ft.... and especially municipal metal
> water pipe systems.]
> ...
>
> If intended only for bonding, the NEC required bonding conductor would
> be much smaller than the GEC that is actually required.
> ...
>
> The link is actually a IEEE document, "How to protect hour house and its
> contents from lightning" probably of great interest to any one still on
> this thread, very good - good post. I presume this quote is that
> connections cannot be made directly to a water pipe for communications
> protectors or other earthing or bonding purposes (although, IIRC, they
> can be made within 5' of the entrance). I presume it is not saying water
> pipes can't be used as a ground electrode because the NEC requires them
> to be used as a grounding electrode.
>
> From page 7:"The NEC/CEC requirements for connecting all metal piping
> and large metal parts of the structure to the building ground serve two
> purposes: If there is metallic buried water piping, bonding it to the
> building ground improves the quality of that ground. Also, in the rare
> event of a direct strike to the piping, or to a metallic part of the
> structure, the ground bond conducts the lightning currents safely into
> the building ground."
> ...
>
> Cite a source that agrees with your isolator argument.
> ...
>
> I'm not aware any signal utilities required a dedicated earthing. In any
> case the NEC requires all earthing to be tied together into one system.
> And we both believe in single point ground where power
> neutral-ground/bond connection and signal protector earthing connection
> are tied with minimal length and earthed together. Dedicated earth ground??
> ...
>
> In your excelent Holt/IEEE post, Fig 7 illustrates a TV protected by a
> plug-in point-of-use multi-port surge suppressor. The illustration has a
> cable ground block remote from the electrical service and attached to it
> by a ground wire. The cable has a lighting strike and the ground current
> lifts the cable ground block 10kV above the service panel. At the TV the
> cable is at 10kV with respect to the TV, not recommended. With a
> multi-port suppressor installed, at the suppressor (at the TV) the cable
> ground is connected to the power ground. These points thus will be at
> the same voltage although that voltage will be thousands of volts
> different from the electrical service and the cable ground block. Since
> the surge suppressor clamps hot, neutral, and cable center conductor to
> that local reference ground the TV is not damaged although it is at
> thousands of volts above 'absolute' ground. The TV has not been
> protected by diverting the surge to ground but by clamping all wires to
> a common reference point.
>
> This illustrates protection primarily by clamping action, not diversion
> to ground - common to plug-in suppressors. Plug-in suppressors are
> strongly supported by this - your - link. Also by another of your links
> and the NIST in a previous post.
>
> In the meantime you have not furnished one or two links that clearly
> demonstrate that "only" diversion works. Musta forgot again
Did not forget. But a large number of facts have not yet been
established. The answer (and I did not make that claim) is found long
after basics have first been established. Because we can discuss
SP200, first we must do SP101.
| |
| Ben Miller 2006-04-19, 12:21 pm |
| "w_tom" <w_tom1@usa.net> wrote in message
news:1145417876.736774.193440@g10g2000cwb.googlegroups.com...
> Structural metal work or | | |