surge protection built into ordinary household electronics

[LVMarc]

Again, most of this is wrong.

There are single point grounds, and there are multi-point grounds.
There are benefits and drawbacks to both systems, and I'm not getting
into them here until we correct a few misconceptions first.

1 - WHEN LIGHTING STRIKES, THERE IS A SIGNIFICANT FAULT CURRENT
FLOWING IN THE EARTH. ANY CONDUCTOR LOCATED IN THAT EARTH WILL
DEVELOP A CHARGE. THE MAGNITUDE OF THE POTENTIAL IS DEPENDANT ON MANY
THINGS - NOT ALL OF THEM KNOWABLE IN ADVANCE.

Period. End of story.

2 - JUST LIKE HOUSE CURRENT, LIGHTNING SUFFERS FROM SIGNIFICANT SKIN
EFFECT LOSSES.

Therefore, you are always better off to use thin copper sheets (or
copper braiding) for grounding, rather than big honkin' ground rods.
Only the surface-area of the rod conducts, and it exhibits a great
deal of inductance at VHF (which is what lightning mostly is.) So,
worthless. (or at least, never as good as you might expect / hope. :
( ...Unless you can't properly solder copper flashing, then you're
usually better off with a ground rod and a clamp.

3 - THE CURRENT IS TREMENDOUS. It will conduct across air, just as
easy as copper.
It depends on where the leader, or M-return strokes, have been
established before the lightning actually struck. (You can use a Boys
Camera to test this theory, if you are so inclined...) So, if the pre-
strike ionized path did not happen to include a nice conductive path
to your ground system(s) (i.e., rods, halo, X-it Rods, whatever...)
you are S-O-L. A typical strike averages approx 20,000 to 40,000
Amps. Individual strikes can be MUCH larger.

4 - EVERYTHING LOOKS LIKE "GROUND" WHEN YOU ARE CHARGED TO THAT
POTENTIAL.

5 - GROUND RODS AT HOUSES ARE THERE PRIMARILY TO CLEAR FAULTS (i.e.,
to ensure that a fuse or circuit breaker trips quickly!) THEY ARE NOT
THERE FOR LIGHTING PROTECTION PER SE, BUT BECAUSE THEY REPRESENT A LOW
CURRENT PATH TO "GROUND", THEY CAN BE QUITE EFFECTIVE.

6 - The NEC says drive 1 ground rod. If < 25 ohms cannot be
established with 1 rod, drive ONE more rod at least (x)-feet away. I
don't recall how far?, but it's like 6 to 10 feet. Just enough so
that the "earth" it "sees" is different "earth" from what the other
rod "sees". Now, no matter what the dual-rod connection is reading,
EVEN IF IT IS 200-OHMS!, it meets NEC Code!!!! - And that means
you're either at the beach with crap sandy soil, or on a volcano with
lava rock, or maybe trying to gound to solid rock. Note: You really
should drive some more ground rods, or switch to a different method of
grounding, even though the NEC does not require you to do so, and even
if the building inspector says you're good....

In either of these situations, you could try Bentonite, or salted
rods, or both.
You could trench out long radials of copper flashing and cover them
with salted soils, etc...
50-50 Flake Calcium Carbonate and Rock Salt works wonders by the
way,and much easier to get than Copper Sulfate. (But neither of them
are particularly good for the grass for all you do-it-yourself
homeowners out there!!) Plus its gets quite hot as it is an
exothermic reaction. Wear PPE.

As for Halo ground systems, these are usually (effectively) multi-
point grounds, and the idea is to reduce the path length to ground,
and try to maintain the same potential when the ground does elevate.
The inductance effectively limits a discharge path, so you get the
idea why some folks use them. I find the problem with them is that it
is (expensive) and next to impossible to keep this grounding separate
from the Neutral coming in to the structure. The famous Motorola
"R-56 Standard" was notorious for violating this, but I guess they
were more concerned about radio transmitter antenna / lightning issues
than compliance with Code.

As we all know (because we are all NEC experts here), you MUST not
bond the neutral to ground past the service entrance (main breaker in
most situations) becuase doing so creates a lethal ground fault
condition IF the Neutral to the building ever gets disconnected or
damaged. All the conduits - which should be at ground potential -
would then be carrying current.

And if lighting struck in that situation..... Good luck!!!
I would not endorse a design that sacraficed personnel protection for
equipment protection.
When this is done, I believe other engineering controls are prudent to
protect against bodily harm, such as a prohibition against working
during electrical storms, etc....

Oh, I forgot one. Separately derived grounds (such as one building
feeding another) can have
"common earthing" much greater than 10 feet. "common earthing" is a
made up term anyway, so one can say whatever they want about that....
It is meaningless.

Another one. The guy who got injured --.
The equipment DOES NOT MATTER!. He could have been standing with his
feet apart. Lighting strikes nearby, and a current starts to flow in
the Earth. Now, Earth, like everything else, has resistance. By ohms
law, there can be a SIGNIFICANT potential between the person's two
feet. The right foot could be at 1000 Volts potential, and the left
at 5,000 Volts. The difference is enough to cause electrocution
irrespective of the location (or even existence) of the machinery!!
It is also possible a current path to/through the equipment occured;
we just don't know.

You can sum up the "valid" portions of Tom's reply thusly:
Each level of protection tends to peel off some of the energy of the
stroke. With enough suitable protection, the remaining energy can be
brought down to a level where (hopefully), gizmos and people can live
peacefully. Unfortunately, as we know, this is not always the case,
even with well engineered ground systems - single point or
otherwise.

(Not talking about Faraday cages here, which is a special case.)
Also not talking about ball lightning, which again is a special case.

-mpm

here is a link to a consumer ecie for pstn ad voip automatic phone
switching, that details the surge protection apsepcts of the design and
product

http://reviews.ebay.com/Surge-Prote...-VOIP-PSTN-adapter_W0QQugidZ10000000003242759

Marc

 

[w_tom]

here is a link to a consumer ecie for pstn ad voip automatic phone
switching, that details the surge protection apsepcts of the design and
product

http://reviews.ebay.com/Surge-Protection-consumer-electronic-VOIP-PST...

The eBay guide describes and does not distinguish between the two
types of protectors: series mode and shunt mode. Series mode
protectors attempt to block or filter a surge. However if three miles
of sky could not stop that surge, then what good will a blocking
device such as polyfuse, inductor, transformer, galvanic isolation, or
a UPS do? Not much except as supplementary protection. Every
protection system starts by shunting the surge to earth. That is what
Ben Franklin did to protect church steeples. Connecting to earth
ground is what MOVs, Gas Discharge Tubes (GDTs), avalanche diodes, or
crowbar circuit does when properly earthed (including a 'less than 10
foot' connection).

Series mode protection is typically part of the protection inside
all appliances. As noted earlier, all appliances have internal
protection. But again, the shunt mode protection must earth a surge
so that protection inside appliances and so that series mode
protectors will not be overwhelmed.

That article gets confused. For example, it states

"On line" UPSs provide the best protection.

Hardly. The online UPS will be best and yet only act as a series mode
protector? Hardly.

What an 'online UPS' would hope to accomplish is already inside
electronic power supplies. Meanwhile the green safety ground wire has
a long history of shunting (connecting, diverting, earthing) a surge,
bypassing the 'online UPS', and destructively into an adjacent
appliance.

UPS for effective protection is the building wide version with a
necessary and short earthing connection. Far more effective because
is uses shunt mode protection connected short to earth. If an 'online
UPS' were recommended by facts, then a UPS numerical spec sheet could
list each type of surge AND numbers for that protection. Plug-in
'online UPS' for surge protection is promoted by myths; not by
manufacturer numerical specification sheets.

Why does the telco suffer maybe 100 surges during each
thunderstorm? Why does that computer connected to overhead wires all
over town not suffer surge damage? No damage from direct lightning
strikes is routine. Telco connects each incoming wire to a single
point earthing electrode AND wants those protectors to be as much as
50 meters distant from the electronics. Telcos routinely use shunt
mode protection. That separation is additional protection.

Meanwhile mpm defines massive protection but ignores what is more
than sufficient for most homes. Since most homes have virtually no
protection, then a properly earthed 'whole house' protector with
necessary earthing is a massive improvement. some locations
massively expand that earthing so that even the extremely rare 200,000
amp surge causes no damage. mpm claims that a system more than
sufficient for 40,000 amps is not sufficient because it is not
expanded for the 200,000 amp surge.

If fault current were so massive, then lightning rods would not
work. Then NYC TV and FM stations struck 25 times annually would
suffer massive damage. 25 direct strikes and no damage is reality
because earthing direct lightning strikes is trivial. The US
Forestry Service determined that well over 95% of trees struck by
lightning leave no appreciable indication. Why? The energy is
actually quite low and easily shunted to earth without damage. But
that assumes the earthing path is properly installed. Earathing need
not be massive as mpm claims. A direct lightning strike that will not
harm trees can still do massive damage to household appliances if not
earthed at the service entrance.

What are the current ratings of minimally acceptable 'whole house'
protectors? 50,000 amps. Lightning (20,000 to 40,000 amps) that
strikes AC electric utility wires distributes that current to many
earthing electrodes. Most of the current would flow through the
primary protection system. Lesser currents to the many earthing
electrodes at many neighborhood homes. IOW a direct strike is well
below 50,000 amps - the rating on even minimally sufficient
protectors.. Responsible companies such as Square D, GE, Siemens,
Intermatic, Cutler-Hammer, Leviton, etc make a 'whole house' protector
for earthing direct lightning strikes. Solutions promoted on myths
such as products from APC, Belkin, Panamax, and Tripplite hope you
don't notice how little current their protectors will withstand - and
not earth ground connection.

Direct lightning strikes are made irrelevant by properly earthed
'whole house' protectors actually designed for those currents and with
short earthing connections. Since plug-in protectors don't have a
dedicated earthing path, then those ineffective protectors neither
claim to protect nor are rated to conduct significant current.

mpm also claims lightning is a VHF event. Little energy is in those
frequencies. He is confusing NEMP with a lightning strike. However
reason for short earthing connections, no sharp bends, no splices,
earthing wire not inside metallic conduit, etc: lightning is radio
frequency electricity (just not VH frequencies). For residental
buildings, that earthing wire from each utility wire to a common
earthing electrode should be 'less than 10 feet'. Shorter means even
better protection.

A halo ground is not a multipoint earthing system. A halo ground
makes earth beneath the building into one large 'single point earth
ground'. Halo grounds or Ufer ground cost so little and provide
massive protection by creating both conductivity and equipotential.
mpm discussed some methods to enhance both conductivity and
equipotential. But the halo ground is a classic example of single
point earthing.

Household earthing rod (which also shunt faults to earth and trip
circuit breakers for human safety) performs multiple functions. If
care is not taken in locating and connecting to that earthing rod,
then electrode's other function (earthing surges) will not be
effective. Electricians are taught a code that is only concerned with
human safety. For transistor safety, that earthing electrode must
exceed post 1990 code requirements. Massive protection is provided by
properly installed ground rod. And then lesser improvements are made
by making that earthing even better (ie halo ground, Ufer ground, a
network of ground rods, etc). Many locations will spend massive more
money just to make smaller improvements - because even the 200,000 amp
lightning strike must not cause damage.

Florida has sandy soil and many more lightning surges - two
conditions that require even better household earthing for surge
protection. And example of how best protection is installed when soil
is poor and lightning strikes so frequent:
http://members.aol.com/gfretwell/ufer.jpg

Again, protection is defined by the earthing system - not by a plug-
in protector or 'online UPS'.

Bottom line: neither series nor shunt mode protectors define
protection. Earthing (including connection to that electrode)
determines quality of protection. No earth ground means no effective
protection. Plug-in protectors (including 'online UPS') avoid all
discussion about earthing since effective protection is neither
provided nor claimed. A protector is only as effective as its earth
ground which Franklin even demonstrated in 1752.

 

[w_tom]

here is a link to a consumer ecie for pstn ad voip automatic phone
switching, that details the surge protection apsepcts of the design and
product

http://reviews.ebay.com/Surge-Protection-consumer-electronic-VOIP-PST...

The eBay guide describes and does not distinguish between the two
types of protectors: series mode and shunt mode. Series mode
protectors attempt to block or filter a surge. However if three miles
of sky could not stop that surge, then what good will a blocking
device such as polyfuse, inductor, transformer, galvanic isolation, or
a UPS do? Not much except as supplementary protection. Every
protection system starts by shunting the surge to earth. That is what
Ben Franklin did to protect church steeples. Connecting to earth
ground is what MOVs, Gas Discharge Tubes (GDTs), avalanche diodes, or
crowbar circuit does when properly earthed (including a 'less than 10
foot' connection).

Series mode protection is typically part of the protection inside
all appliances. As noted earlier, all appliances have internal
protection. But again, the shunt mode protection must earth a surge
so that protection inside appliances and so that series mode
protectors will not be overwhelmed.

That article gets confused. For example, it states

"On line" UPSs provide the best protection.

Hardly. The online UPS will be best and yet only act as a series mode
protector? Hardly.

What an 'online UPS' would hope to accomplish is already inside
electronic power supplies. Meanwhile the green safety ground wire has
a long history of shunting (connecting, diverting, earthing) a surge,
bypassing the 'online UPS', and destructively into an adjacent
appliance.

UPS for effective protection is the building wide version with a
necessary and short earthing connection. Far more effective because
is uses shunt mode protection connected short to earth. If an 'online
UPS' were recommended by facts, then a UPS numerical spec sheet could
list each type of surge AND numbers for that protection. Plug-in
'online UPS' for surge protection is promoted by myths; not by
manufacturer numerical specification sheets.

Why does the telco suffer maybe 100 surges during each
thunderstorm? Why does that computer connected to overhead wires all
over town not suffer surge damage? No damage from direct lightning
strikes is routine. Telco connects each incoming wire to a single
point earthing electrode AND wants those protectors to be as much as
50 meters distant from the electronics. Telcos routinely use shunt
mode protection. That separation is additional protection.

Meanwhile mpm defines massive protection but ignores what is more
than sufficient for most homes. Since most homes have virtually no
protection, then a properly earthed 'whole house' protector with
necessary earthing is a massive improvement. some locations
massively expand that earthing so that even the extremely rare 200,000
amp surge causes no damage. mpm claims that a system more than
sufficient for 40,000 amps is not sufficient because it is not
expanded for the 200,000 amp surge.

If fault current were so massive, then lightning rods would not
work. Then NYC TV and FM stations struck 25 times annually would
suffer massive damage. 25 direct strikes and no damage is reality
because earthing direct lightning strikes is trivial. The US
Forestry Service determined that well over 95% of trees struck by
lightning leave no appreciable indication. Why? The energy is
actually quite low and easily shunted to earth without damage. But
that assumes the earthing path is properly installed. Earathing need
not be massive as mpm claims. A direct lightning strike that will not
harm trees can still do massive damage to household appliances if not
earthed at the service entrance.

What are the current ratings of minimally acceptable 'whole house'
protectors? 50,000 amps. Lightning (20,000 to 40,000 amps) that
strikes AC electric utility wires distributes that current to many
earthing electrodes. Most of the current would flow through the
primary protection system. Lesser currents to the many earthing
electrodes at many neighborhood homes. IOW a direct strike is well
below 50,000 amps - the rating on even minimally sufficient
protectors.. Responsible companies such as Square D, GE, Siemens,
Intermatic, Cutler-Hammer, Leviton, etc make a 'whole house' protector
for earthing direct lightning strikes. Solutions promoted on myths
such as products from APC, Belkin, Panamax, and Tripplite hope you
don't notice how little current their protectors will withstand - and
not earth ground connection.

Direct lightning strikes are made irrelevant by properly earthed
'whole house' protectors actually designed for those currents and with
short earthing connections. Since plug-in protectors don't have a
dedicated earthing path, then those ineffective protectors neither
claim to protect nor are rated to conduct significant current.

mpm also claims lightning is a VHF event. Little energy is in those
frequencies. He is confusing NEMP with a lightning strike. However
reason for short earthing connections, no sharp bends, no splices,
earthing wire not inside metallic conduit, etc: lightning is radio
frequency electricity (just not VH frequencies). For residental
buildings, that earthing wire from each utility wire to a common
earthing electrode should be 'less than 10 feet'. Shorter means even
better protection.

A halo ground is not a multipoint earthing system. A halo ground
makes earth beneath the building into one large 'single point earth
ground'. Halo grounds or Ufer ground cost so little and provide
massive protection by creating both conductivity and equipotential.
mpm discussed some methods to enhance both conductivity and
equipotential. But the halo ground is a classic example of single
point earthing.

Household earthing rod (which also shunt faults to earth and trip
circuit breakers for human safety) performs multiple functions. If
care is not taken in locating and connecting to that earthing rod,
then electrode's other function (earthing surges) will not be
effective. Electricians are taught a code that is only concerned with
human safety. For transistor safety, that earthing electrode must
exceed post 1990 code requirements. Massive protection is provided by
properly installed ground rod. And then lesser improvements are made
by making that earthing even better (ie halo ground, Ufer ground, a
network of ground rods, etc). Many locations will spend massive more
money just to make smaller improvements - because even the 200,000 amp
lightning strike must not cause damage.

Florida has sandy soil and many more lightning surges - two
conditions that require even better household earthing for surge
protection. And example of how best protection is installed when soil
is poor and lightning strikes so frequent:
http://members.aol.com/gfretwell/ufer.jpg

Again, protection is defined by the earthing system - not by a plug-
in protector or 'online UPS'.

Bottom line: neither series nor shunt mode protectors define
protection. Earthing (including connection to that electrode)
determines quality of protection. No earth ground means no effective
protection. Plug-in protectors (including 'online UPS') avoid all
discussion about earthing since effective protection is neither
provided nor claimed. A protector is only as effective as its earth
ground which Franklin even demonstrated in 1752.

 

[mpm]

Series mode protection is typically part of the protection inside
all appliances. As noted earlier, all appliances have internal
protection.

TOTALLY NOT TRUE!
"Some" appliances have protection inside. Not all. And of those that
do, not all are effective.

Why does the telco suffer maybe 100 surges during each
thunderstorm? Why does that computer connected to overhead wires all
over town not suffer surge damage? No damage from direct lightning
strikes is routine.

At best, this statement demonstrats a 1930's understanding of
telephone electronics.
Nowadays, the "wires" coming into a cental office are fiber-optic (or
RF coax).
These go out to SLIC's, which eventually terminate in the familair tip
& ring.
That said, "Yes, there is significant protection present. Very much
in line with my prior postings."

Meanwhile mpm defines massive protection but ignores what is more
than sufficient for most homes. Since most homes have virtually no
protection, then a properly earthed 'whole house' protector with
necessary earthing is a massive improvement. some locations
massively expand that earthing so that even the extremely rare 200,000
amp surge causes no damage. mpm claims that a system more than
sufficient for 40,000 amps is not sufficient because it is not
expanded for the 200,000 amp surge.

I did not say that, in fact, I said the exact opposite.
And, you are also assuming the strike is not direct, but is instead
dissipated before reaching the home. Or for that matter, that the
conduction path was the utility lines....

If fault current were so massive, then lightning rods would not
work. Then NYC TV and FM stations struck 25 times annually would
suffer massive damage. 25 direct strikes and no damage is reality
because earthing direct lightning strikes is trivial. The US
Forestry Service determined that well over 95% of trees struck by
lightning leave no appreciable indication. Why? The energy is
actually quite low and easily shunted to earth without damage. But
that assumes the earthing path is properly installed. Earathing need
not be massive as mpm claims. A direct lightning strike that will not
harm trees can still do massive damage to household appliances if not
earthed at the service entrance.

You should be aware that you are speaking with one of the individuals
formerly responsible for antenna grounding systems at the ESB, and
also the WTC North Tower.... (and 4500 other towers in the US, Canada
and a handful in the UK.)

Your numbers are way off. And as for trees, just as many burn into
flames and start forest fires.

By the way, broadcast transmitters, antennas and transmission lines
are damaged all the time!
You are totally pulling this out of your backside.

What are the current ratings of minimally acceptable 'whole house'
protectors? 50,000 amps. Lightning (20,000 to 40,000 amps) that
strikes AC electric utility wires distributes that current to many
earthing electrodes. Most of the current would flow through the
primary protection system. Lesser currents to the many earthing
electrodes at many neighborhood homes. IOW a direct strike is well
below 50,000 amps - the rating on even minimally sufficient
protectors.. Responsible companies such as Square D, GE, Siemens,
Intermatic, Cutler-Hammer, Leviton, etc make a 'whole house' protector
for earthing direct lightning strikes. Solutions promoted on myths
such as products from APC, Belkin, Panamax, and Tripplite hope you
don't notice how little current their protectors will withstand - and
not earth ground connection.

As long as you're quoting "responsible" companies, don't forget to
include the commerical stuff.
Try: Liebert, LEA Dynasytem, etc... (OK, even GE-Challenger, but I
don't like their stuff.)

The strike is what it is. I agree it usually (but not always!!)
dissipates by the time it reaches the house. No doubt that some
people claim to have been "hit" by lightning, when indeed, the strike
was only nearby. Surely you know the difference.

Direct lightning strikes are made irrelevant by properly earthed
'whole house' protectors actually designed for those currents and with
short earthing connections. Since plug-in protectors don't have a
dedicated earthing path, then those ineffective protectors neither
claim to protect nor are rated to conduct significant current.

This statement is total B/S. Not true. Not even remotely true.
I personally have seen at least one of each manufacturer's brand you
mentioned above totally smoked by lightning damage. Some even blew
off the wall, and were previously "massively" grounded.

mpm also claims lightning is a VHF event. Little energy is in those
frequencies. He is confusing NEMP with a lightning strike.

I am not confusing anything. You are just wrong.
Besides, I'm absolutely certain you cannot have a strike without
generating a magnetic field.
Unless of course you know of some magical way to transfer 20,000 to
40,000 amps in a conductor (air, or otherwise) without generating a
field. Hey, let's patent that baby! We could all retire!

However

reason for short earthing connections, no sharp bends, no splices,
earthing wire not inside metallic conduit, etc: lightning is radio
frequency electricity (just not VH frequencies). For residental
buildings, that earthing wire from each utility wire to a common
earthing electrode should be 'less than 10 feet'. Shorter means even
better protection.

I would really like to introduce you to Martin Uman sometime....
I'm sure you can get his texts in any decent engineering or college
bookstore.

A halo ground is not a multipoint earthing system. A halo ground
makes earth beneath the building into one large 'single point earth
ground'. Halo grounds or Ufer ground cost so little and provide
massive protection by creating both conductivity and equipotential.
mpm discussed some methods to enhance both conductivity and
equipotential. But the halo ground is a classic example of single
point earthing.

I agree that is the theory. (Well, not quite, but let's not split
hairs on the small stuff.)
It would probably be a really good exercise for you to some go do a
step-potential test on a Halo ground system sometime. And then
compare those results to a Biddle 4-point test of the same system.

Household earthing rod (which also shunt faults to earth and trip
circuit breakers for human safety) performs multiple functions. If
care is not taken in locating and connecting to that earthing rod,
then electrode's other function (earthing surges) will not be
effective. Electricians are taught a code that is only concerned with
human safety. For transistor safety, that earthing electrode must
exceed post 1990 code requirements.

Again, yet another total assertion!
There is no substantial change in the Code since pre-1990 relating to
"transistor safety".
If you want a "transistor safety" code, try UL-1449, which even I
think is barely worth the effort. A 1N4001 will get you that much...
(OK, maybe not, but you'd be suprised how close!)

Massive protection is provided by

properly installed ground rod. And then lesser improvements are made
by making that earthing even better (ie halo ground, Ufer ground, a
network of ground rods, etc). Many locations will spend massive more
money just to make smaller improvements - because even the 200,000 amp
lightning strike must not cause damage.

Florida has sandy soil and many more lightning surges - two
conditions that require even better household earthing for surge
protection. And example of how best protection is installed when soil
is poor and lightning strikes so frequent:
http://members.aol.com/gfretwell/ufer.jpg

Again, protection is defined by the earthing system - not by a plug-
in protector or 'online UPS'.

I hear you here. But remember: Inherent in the notion of
"protection" is a savings of (your choice of: time, money, effort or
expense). If a $500 UPS "saved" a $1-Million installation because it
took the brunt of the lightning damage, then I would call that
"Protection"!. Reasonable people can differ about this, however.
(Wealthy, reasonable people I might add.)

Bottom line: neither series nor shunt mode protectors define
protection. Earthing (including connection to that electrode)
determines quality of protection. No earth ground means no effective
protection. Plug-in protectors (including 'online UPS') avoid all
discussion about earthing since effective protection is neither
provided nor claimed. A protector is only as effective as its earth
ground which Franklin even demonstrated in 1752.

You are aware that lightning also strikes from ground to sky,
right??......
In addition to sky-to-earth, and sky-to-sky (sheet lightning).

-mpm

 

[mpm]

How did this morph into a discussion about structure grounding for
lightning abatement?

The original poster wanted to prevent kickback on his 5V relay.
I (and others) suggested a simple diode, but he seems to want to go
with a TVS of some sort.

-mpm

 

[Bud--]

w_tom wrote:


The best information on surges and surge protection I have seen is at:
http://omegaps.com/Lightning Guide_FINALpublishedversion_May051.pdf
- the title is "How to protect your house and its contents from
lightning: IEEE guide for surge protection of equipment connected to AC
power and communication circuits" published by the IEEE in 2005 (the
IEEE is the dominant organization of electrical and electronic engineers
in the US).
And also:
http://www.nist.gov/public_affairs/practiceguides/surgesfnl.pdf
- this is the "NIST recommended practice guide: Surges Happen!: how to
protect the appliances in your home" published by the National
Institute of Standards and Technology (the US government agency formerly
called the National Bureau of Standards) in 2001

The IEEE guide is aimed at those with some technical background. The
NIST guide is aimed at the unwashed masses.

Since plug-in protectors don't have a
dedicated earthing path, then those ineffective protectors neither
claim to protect nor are rated to conduct significant current.

The IEEE guide explains plug-in suppressors work by CLAMPING the voltage
on all wires (signal and power) to the common ground at the suppressor.
Plug-in suppressors do not work primarily by earthing. The IEEE guide
explains earthing occurs elsewhere. (Read the guide starting pdf page 40).

Plug-in suppressors certainly claim to protect - as do some UPSs.
Ratings range from junk to very high. Plug-in suppressors with very high
ratings are readily available - I recently bought one for $25 with surge
current ratings of 3 x 30,000A. But the surge current is greatly limited
on a branch circuit compared to a power service.

Note that all interconnected equipment needs to be connected to the
same plug-in suppressor, or interconnecting wires needs to go through
the suppressor. External connections, like phone, CATV, ... also need to
go through the suppressor. Connecting all wiring through the suppressor
prevents damaging voltages between power and signal wires. These
multiport suppressors are described in both the IEEE and NIST guides.

A halo ground is not a multipoint earthing system.

From
http://www.lightningsafety.com/nlsi_lhm/grounding_definitions.html
“Halo Grounded Ring: A grounded No. 2 wire, installed around all four
walls inside a small building, at an elevation of approx. six inches
below the ceiling. There are drops installed from the halo to the
equipment cabinets and to waveguide ports, interior cable trays etc.

Halo grounds or Ufer ground cost so little and provide
massive protection by creating both conductivity and equipotential.
mpm discussed some methods to enhance both conductivity and
equipotential.

In the US, Ufer (concrete encased electrode) grounds are required for
new construction with footings or foundations. A Ufer ground doesn’t
necessarily give you an equipotential.

Massive protection is provided by
properly installed ground rod. And then lesser improvements are made
by making that earthing even better (ie halo ground, Ufer ground, a
network of ground rods, etc).

For reasons detailed by mpm, ground rods are lousy grounding electrodes.
Ufer grounds are quite good.

Again, protection is defined by the earthing system - not by a plug-
in protector or 'online UPS'.

As explained in the IEEE guide, for anyone able to read, plug-in
suppressors work primarily by clamping, not earthing. And both guides
say plug-in suppressors are effective.

Bottom line: neither series nor shunt mode protectors define
protection. Earthing (including connection to that electrode)
determines quality of protection. No earth ground means no effective
protection.

w_ has a religious belief (immune from challenge) that surge protection
must use earthing. Thus in his view plug-in suppressors (which are not
well earthed) can not possibly work. The IEEE and NIST don’t agree.

Plug-in protectors (including 'online UPS') avoid all
discussion about earthing since effective protection is neither
provided nor claimed. A protector is only as effective as its earth
ground which Franklin even demonstrated in 1752.

And a final statement of religious belief in earthing. The IEEE guide
explains plug-in suppressors work primarily by clamping, not earthing.

A 15 year old could easily find claims of protection for plug-in
suppressors.

The issue isn't earthing. The only question is whether plug-in
suppressors work.

And both the IEEE and NIST guides say plug-in suppressors are effective.
A UPS may include the same protection.

----------
MOV protection could also be built into Matt’s device. It is all a
trade-off of value of the device and cost of protection. A MOV, with a
fuse in front of it to protect if the MOV fails (high current thermal
runaway), would provide significant protection. but so will the
transformer and filter caps.

 

[Matt]

How did this morph into a discussion about structure grounding for
lightning abatement?

The original poster wanted to prevent kickback on his 5V relay.

You're right, but that was on two other threads. I don't think
lightning is so far off topic, although I can't say that I've understood
it very well. Since you've done so much work on lightning abatement, I
expect you would have run into w_tom on Usenet before.

 

[w_tom]

All electronic appliances have internal protection. Protection is
required by multiple industry standards. Even the CBEMA demanded
protection up to 600 volts on 120 volt appliances 35 years ago. Intel
standards for ATX power supply demand at least 1000 volts.

All appliances have internal protection which is why power cycling a
pump, refrigerator, or vacuum cleaner causes no damage. Internal
protection that can be overwhelmed if typically destructive surges are
not earthed before entering a building.

So you are trooping every day to the hardware store to replace
dimmer switches damaged by the refrigerator? Even dimmer switches
contain internal protection. Protection is integrated within the
design.

Show me a CO that does not have tens of thousands of copper wires
connected directly to the building? Yes, SLICs using fiber optics
also connect distant areas to that CO (which is why some could not
have DSL service). But by far the majority of connections to a
telco's computer is POTS - plain old two wire copper. And coax cable
is another 'carrier' of potentially destructive surges. These wires
are overhead all over town. And still a CO is not damaged by
thunderstorms. Each thunderstorm even exposed the original ESS1
electronic switching computers to hundreds of surges without damage.
Why? Telco properly earthed protectors. No damage from thunderstorms
is routine. So routine that damage is considered a human failure.

If that is in agreement with your prior posting, then you have
posted in agreement with what I have posted. Homes must accomplish
same protection using, at minimum, a ground rod. A rod is installed
for human safety. A rod that also performs transistor safety.

Post 1990 code was not changed for transistor safety. Apparently
mpm does not grasp what the NEC addresses: human safety - not
transistor safety. Transistor safety is why the 1990 code must be
exceeded for transistor safety. If earthing does not meet post 1990
codes, then earthing is not sufficient for transistor safety. That was
stated before and reposted because mpm has taken false assumptions not
found in earlier postings.

Protection for residences must meet and exceed post 1990 NEC
earthing requirements. Earthing provides the protection. Same reason
why telco with overhead copper wires all over town did not and does
not suffer damage during thunderstorms.

Well over 95% of trees are struck by lightning with no appreciable
damage. Where is that published? mpm recommended Martin Uman. That
statement is directly from Dr Uman's book.

And as for trees, just as many burn into flames and start
forest fires.

Well that's just not in the numbers or in anything from Dr Uman.
Lightning strikes are so easily earthed that most trees are struck
without any appreciable indication. Only a rare lightning strike
causes a forest fire. Protecting electronic and homes from lightning
damage is also so easy. Why does so much damage occur? We still
build homes as if the transistor does not exist. Earthing in most
older homes is not sufficient for transistor protection. But again,
for transistor protection, a home must meet and exceed post 1990
earthing requirements. Many if not most older homes do not meet that
simple requirement. I see maybe 2 out of ten older homes have all but
no earthing. Therefore surge damage is directly traceable to human
failure.

Maybe a $500 UPS protects a computer - a big maybe. If a $million
equipment. then the UPS is installed (and earthed) at the service
entrance. Then the UPS also provides surge protection. Earthing
defines protection. A $million equipment with a $500 plug-in UPS that
only provides battery backup - foolish.

$500 UPS does not even claim to provide such protection. For
residences, informed homeowners install and earth one 'whole house'
protector that actually does earth surges. Such protectors even sell
in Lowes and Home Depot for less than $50. That's effective
protection for about $1 per protected appliance. Protection also for
electronics far more important such as furnace, smoke detector, and
bathroom GFCIs.

Lightning that does not cause appreciable damage to trees can cause
significant damage to household appliances. Simply upgrading earthing
and installing a 'whole house' protector is a massive improvement in
electronics protection. A solution that costs so little, is so easily
implemented (where soil and environmental conditions are not extreme),
and is still not required in new homes today. Same solution is why
telcos routinely suffer hundreds of surges even 40 years ago without
semiconductor damage.

Meanwhile UL1449 says nothing about transistor safety. mpm should
know that simple fact. A device can completely fail during UL1449
testing and still obtain UL1449 approval. UL does not care whether
protector provided protection. UL only cares about human safety.
When it fails quickly and provides zero protection, it must not spit
sparks and flame. That is sufficient for UL1449 approval. Anyone
familiar with basic protection knows UL1449 says nothing about
transistor safety. UL1449 says even a grossly undersized and
completely ineffective protector does not burn down the house.

The building's lightning rod was earthed by a cable that ran outside
the building and only four feet from a PC. During the direct strike,
fields on that lightning rod wire were massive - and caused no
computer interruption. Surges from fields is overhyped and easily
eliminated. Lightning strike earth some forty feet from a long wire
(100 foot) antenna. It induced thousands of volts on that wire. And
then we earthed that wire with an NE-2 neon lamp. Milliamps through
that neon glow lamp were enough to reduce induced voltage from
thousands of volts to tens of volts. Yes, nearby fields can create
large voltages. And very little current. That thousands of volts
reduced to near zero by an NE-2 neon lamp. Fields created by nearby
strikes easily made irrelevant by simple solutions. Massive voltages
induced on wires by nearby strikes made totally irrelevant when a
human does his job. Two examples provided.

Protection easily implemented. The hard part is getting humans to
understand the principles. Principle number one: earthing (not a
protector) provided the protection. Even that Principle number one is
so difficult for many who remain in denial - who assume failure is
acceptable.

How did we get here? Last week, replies about motor transients and
lightning were introduced as problems. Lightning is the threat.
Motor noise made completely irrelevant by protection already inside
all electronics. Transients also made further irrelevant by protection
installed to avert lightning damage.