Whole House Surge Suppressor & Lighting Strikes



Here, in Greece, you have to have 3 on the points of an equilateral triangle with sides of 3 meters.
--
Tzortzakakis Dimitrios
major in electrical engineering
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Dimitrios Is that the requirement for a single family home in Greece? Have you seen any information on what the average ground impedance of that Grounding Electrode System is? I'm just interested in how it compares with what we measure here on our dual rod systems. -- Tom Horne
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?Grounding Electrode System is? I'm just interested in ?>how it compares

Yes, all 3 electrodes have to be connected with at least 10 mm^2 (#10) bare copper conductor, and the same conductor to the service (the meter) where neutral and earth are bounded together, usually in a 16 mm conduit, Conflex by www.kouvidis.gr . I have not measured in the field the earth impendance, but in the college we did some measurements. IIRC the impendance was very small. (1-2 ohms). For a residence: #0 service, 3 X 10 mm^2 (#10) 1 X 35 A, single phase or 3 X 16 mm^2 (#8) 1 X 50 A, single phase, 230 V #1 service, 5 X 6 mm^2 (#12) 3 X 25 A, 400 V, three phase #2 service, 5 X 10 mm^2(#10) 3 X 35 A, 400 V. three phase.
--
Tzortzakakis Dimitrios
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Jeff Let me stick an oar in here and make a suggestion. I have had several clients over the forty plus years I have been an electrician that had problems like yours. Two of them are summer camps on ridge top properties. The Mid Atlantic states get a fair amount of lightning and the camps were loosing modems, answering machines, cordless phone bases, and several other items every year. Since they are non profit church camps they do not have the resources to completely eliminate the problems but I've been able to cut it way down. Your house has the same type of wire geography that several of the camps buildings have. Power and other wired services enter at widely separated locations on the building. My next statement will drive some people right up the wall but the solution is much the same as what you do when you use a plug in serge protector. All the plug in surge protector does is keep the voltage between all the connected wires low enough to avoid the flow of destructive currents. It does that by bypassing the equipment it is protecting and allowing the voltage to equalize through the protector rather than destructively through the protected equipment.
Please notice that it is not the absolute voltage relative to the earth that you are trying to reduce. Since the voltage relative to the earth itself IS going to rise during a strike concentrate on seeing that it rises uniformly across the equipment you are trying to protect. You cannot keep the voltage relative to the earth low. But you can keep the voltage difference BETWEEN the several different wires low enough to avoid damage. It will be perfectly fine if the absolute voltage to earth of your various wires rises to several thousand volts as long as all of the wires rise in voltage fairly uniformly. It matters not that your telephone wires and your power wires rise to a couple of thousand volts relative to the earth as long as the difference between them is relatively small. It is the difference of potential between the separate wired utilities; expressed as a relative voltage; that causes current to flow, destructively, through your equipment.
Here is how I would suggest you go about accomplishing the limiting of the difference of potential between the wires that enter your home. Drive a ground rod at each wire entry and install an appropriate protector on each set of wires. If possible the ground rod should be long enough to extend below the permanent moisture level. The ground rods should have earth on all sides. Do not drive them within their own length of deep foundation walls or other underground obstructions. Run the Grounding Electrode Conductor (GEC) specified by the manufacturer of the protector from the protector itself to the ground rod. Connect the GEC to the electrode; in this case a driven rod; by using an acorn clamp or by exothermic welding. Westom's advice on how to run the conductor is valid. Run the GEC as directly as possible. Any bend should be gradual and have a radius no smaller then six inches. You will need to dig a trench halfway around your house run between all of these separate ground rod locations. In that trench you will install a number two copper conductor. That conductor will serve as an additional grounding electrode as well as a bonding conductor. Connect the rods to each other via the number two copper conductor. If your willing to spend the additional money you can use a copper ribbon or strap having the same cross sectional area as the number two copper conductor. Copper strap has a far lower impedance then a regular number two wire. When a voltage is changing very rapidly; as it does during a lightning discharge; it is the impedance of the conductor that matters a lot more then it's DC resistance and less is better. If you want to maximize the effectiveness of the buried conductor as an additional grounding electrode then you will make the trench as deep as practical and at least thirty inches deep. By digging the trench first, and driving the ground rods through the bottom of the trench, you can increase the effective depth of the driven rods and the overall effectiveness of your Grounding Electrode System. It is by bonding all of the electrodes together that you keep the voltage BETWEEN the various wires that enter your home below the damage threshold.
If you have any questions about what I am suggesting you are welcome to ask for clarification here or by direct email. Bonne Chance. -- Tom Horne
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In article < snipped-for-privacy@o36g2000vbl.googlegroup

[...]
My employer has an installation exactly like that you have described at a location on a mountain top (9000ft high) in a remote location. Grounding presented its own problems as it sits on a rock base, where the word "earth" has little meaning. The building surrounding it has an exposed metal frame. Internally to the building, surge diversion is performed using a number of different techniques, including a three-way protector on the mains supply of every connected electronic instrument and computer with as short a connection as possible to a thick copper ribbon (5mm thick x 50mm wide) surrounding the interior of the entire building, to which services and equipment are bonded at frequent intervals and is also itself bonded to the incoming power feed and the external ring.
westom pooh-poohed the concept when I described it some years ago because it did not have, you guessed it, a single whole-structure protector (we could not have fitted one even if we had wanted to because as in Jeff's case, utilities enter the building at opposite ends, some ~100m apart). In addition he twisted my words outright by saying our organisation had not taken sufficient precautions and were willing to accept lightning damage. This was after I had said that the installation was unlikely to survive a direct or very close lightning strike, and over the years it has survived a large number of nearby strikes, which have caused severe damage to other facilities nearby, without any interruption to operation.
--
(\__/)
(='.'=) Bunny says Windows 7 is Vi$ta reloaded.
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You were not pooh-poohed. Your memory is defective because your venom is obvious. You see what you want to see only because you were previously caught and exposed posting myths. Your anger has so demented your memory that you must always attack me rather than post facts.
Surge protection is always about diverting that energy to earth. As posted back then, another accomplished the same thing on a rocky mountain using a similar technique: http://scott-inc.com/html/ufer.htm
There is no magic box. Personal attacks do not change reality. Stated only for benefit of others. Protection is about diverting energy to earth. Absorbing surge energy harmlessly in earth; not inside a building. Which is why a protector is only as effective as its earth ground - no matter how much you dislike that reality.
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In article < snipped-for-privacy@s6g2000vbp.googlegroups

Google proves otherwise, liar.
--
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westom wrote:

Describes w perfectly.

The religious belief in earthing.

Plug-in suppressors are only "magic" to w. If he wasn't hampered by religious blinders he could find out how they work.

w's religious mantra protects him from disturbing thoughts (aka reality).
Still never seen - a source that agrees with w that plug-in suppressors are NOT effective.
And w never answers simple questions: - Why do the only 2 examples of protection in the IEEE guide use plug-in suppressors? - Why does the NIST guide says plug-in suppressors are "the easiest solution"? - Why does the NIST guide say "One effective solution is to have the consumer install" a multiport plug-in suppressor? - How would a service panel suppressor provide any protection in the IEEE example, pdf page 42? - Why does the IEEE guide say for distant service points "the only effective way of protecting the equipment is to use a multiport [plug-in] protector"? - And why aren't airplanes crashing every day - "a protector is only as effective as its earth ground"
For real science read the IEEE and NIST guides. Both say plug-in suppressors are effective.
--
bud--


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Tom, I'm confident your multiple driven ground rod plan would greatly help if not eliminate my problem. However I'd have to cut through a concrete driveway and tear apart a paver patio to go direct burial. The alternative of running the bonding wire through my house is not very appealing to me, don't particularly like the thought of having several KV passing to ground running though wiring inside wood framing. Just driving a proper ground rod without bonding them adequately would create a potential difference between the 3 systems and would most likely make lighting damage more severe.
Proteus, not sure if your serious or being facetious. If you are serious can you provide a link to what you're referring to. However as I stated earlier I live in a woods, the small trees are 60' tall.
wrote:

Jeff Let me stick an oar in here and make a suggestion. I have had several clients over the forty plus years I have been an electrician that had problems like yours. Two of them are summer camps on ridge top properties. The Mid Atlantic states get a fair amount of lightning and the camps were loosing modems, answering machines, cordless phone bases, and several other items every year. Since they are non profit church camps they do not have the resources to completely eliminate the problems but I've been able to cut it way down. Your house has the same type of wire geography that several of the camps buildings have. Power and other wired services enter at widely separated locations on the building. My next statement will drive some people right up the wall but the solution is much the same as what you do when you use a plug in serge protector. All the plug in surge protector does is keep the voltage between all the connected wires low enough to avoid the flow of destructive currents. It does that by bypassing the equipment it is protecting and allowing the voltage to equalize through the protector rather than destructively through the protected equipment.
Please notice that it is not the absolute voltage relative to the earth that you are trying to reduce. Since the voltage relative to the earth itself IS going to rise during a strike concentrate on seeing that it rises uniformly across the equipment you are trying to protect. You cannot keep the voltage relative to the earth low. But you can keep the voltage difference BETWEEN the several different wires low enough to avoid damage. It will be perfectly fine if the absolute voltage to earth of your various wires rises to several thousand volts as long as all of the wires rise in voltage fairly uniformly. It matters not that your telephone wires and your power wires rise to a couple of thousand volts relative to the earth as long as the difference between them is relatively small. It is the difference of potential between the separate wired utilities; expressed as a relative voltage; that causes current to flow, destructively, through your equipment.
Here is how I would suggest you go about accomplishing the limiting of the difference of potential between the wires that enter your home. Drive a ground rod at each wire entry and install an appropriate protector on each set of wires. If possible the ground rod should be long enough to extend below the permanent moisture level. The ground rods should have earth on all sides. Do not drive them within their own length of deep foundation walls or other underground obstructions. Run the Grounding Electrode Conductor (GEC) specified by the manufacturer of the protector from the protector itself to the ground rod. Connect the GEC to the electrode; in this case a driven rod; by using an acorn clamp or by exothermic welding. Westom's advice on how to run the conductor is valid. Run the GEC as directly as possible. Any bend should be gradual and have a radius no smaller then six inches. You will need to dig a trench halfway around your house run between all of these separate ground rod locations. In that trench you will install a number two copper conductor. That conductor will serve as an additional grounding electrode as well as a bonding conductor. Connect the rods to each other via the number two copper conductor. If your willing to spend the additional money you can use a copper ribbon or strap having the same cross sectional area as the number two copper conductor. Copper strap has a far lower impedance then a regular number two wire. When a voltage is changing very rapidly; as it does during a lightning discharge; it is the impedance of the conductor that matters a lot more then it's DC resistance and less is better. If you want to maximize the effectiveness of the buried conductor as an additional grounding electrode then you will make the trench as deep as practical and at least thirty inches deep. By digging the trench first, and driving the ground rods through the bottom of the trench, you can increase the effective depth of the driven rods and the overall effectiveness of your Grounding Electrode System. It is by bonding all of the electrodes together that you keep the voltage BETWEEN the various wires that enter your home below the damage threshold.
If you have any questions about what I am suggesting you are welcome to ask for clarification here or by direct email. Bonne Chance. -- Tom Horne
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I didn't know there was anyone left who hadn't killfiled proteus. He(she/it?) is the resident troll around here and has been for years.
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Tom Horne wrote:

(There is likely only one person that drives up the wall.)

For phone and cable, the NEC requires a ground wire from phone and cable entry protectors to the power grounding system (connection points include to the electrodes or grounding electrode conductor). The NEC requires the wire be 20 ft or less. But for 1 & 2 family dwellings it can longer if there is a grounding electrode (usually rod) near the entry protector, and a min #6 bond back to the power system ground. There is no max length ground wire for dish.
Tom and Jeff are probably well aware of the NEC requirements, but just for a common starting point.
Tom's method would earth all parts of the system, but I am not convinced that the external buried bond, which would also act as a ring ground, would be adequate to keep voltage on the power and signal wires close enough together. The #2 wire probably doesn't have a low enough impedance since the wire inductance (which dominates for surges) is not reduced a lot by larger size. Surge current to earth from surges on incoming power or signal would produce a voltage gradient along the wire. The bond wire length is longer than a bond wire through the house, so a question is whether the earthing effect is adequate to counteract the wire that is longer than the too-long wire through the house.
Another question I have is that during a near lightning strike the earth potential for points that are relatively close together can be far apart in voltage. For instance if lightning hits a near tree, the rod at the phone/cable entry may have a far different potential than the power earthing electrode. It is not obvious to me that the buried bond would adequately equalize the voltages. The IEEE guide has an illustration of a pad mounted A/C compressor/condenser that has a "ground" potential through the pad to earth that is far from the power system "ground" potential during a near lightning strike. The branch circuit "ground" wire has an impedance that is far too high to prevent the difference.
The IEEE guide says a 10 ft "ground" wire from phone entry protector to the ground at the power system may be too long. In the IEEE illustration (starting pdf page 40), with a surge coming in on cable and ground wire from entry protector to power system ground that is too long, the guide says "the only effective way of protecting the equipment is to use a multiport [plug-in] protector."
My alternative would be to earth the system as required by the NEC, then run the phone, cable, ... wires to the area of the power service, install a second set of entry protectors with short ground wires to the power system ground, and distribute from there. A few manufacturers (SquareD comes to mind) make service panel suppressors that include ports to run phone and cable (and dish?) wiring through the suppressor.
--
bud--

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