whole house surge protectors

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On Mon, 8 Oct 2012 10:49:19 -0700 (PDT), " snipped-for-privacy@optonline.net"

Thanks Trader, Gfret, and Ed.,

Oh, yeah, there is one of those two, 8 townhouses away (the other end of this building). It's only 2 feet high. Failed once on July 4th weekend, 29 years ago, but from overuse. Water heater and water failed the same weekend, when I had 3 guests from out of town.

Since I have two metal chimneys, I thought it would be rather easy to ground one of them (although just now I realize I'd have to ground both of them, since the grounded one would stop attracting lightning.)
But I called some national Lighning Hotline number and he kept saying if I didn't live in Florida, I didn't have much of a problem. Huh? But then I got busy with other things. .

That makes sense.

After about 15 years, my burglar alarm keypad/control panel was smoking a little one day, and failed, and might have been damaged by a surge, I guess (even though I had connected it correctly to a 5 foot earth rod) , but so far nothing else.

I bought a double-D surge supprrssor but haven't installed it yet.

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As I understand things, lightning seeks earth ground. By grounding your chimney, you make it an easier path, and therefore more likely to be hit.
Christopher A. Young Learn more about Jesus www.lds.org .
Since I have two metal chimneys, I thought it would be rather easy to ground one of them (although just now I realize I'd have to ground both of them, since the grounded one would stop attracting lightning.)
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Grounding something will not make it stop attracting lightning. Lightning is seeking a path to ground. By grounding a chimney you are providing a safer path. Hopefully if lightning strikes the chimney, most or all of the energy will follow the ground wire you have provided. But, it all depends. The more sharp turns, the longer the wire, etc, the more likely some of the lightning could choose to go another way too.

FL is certainly a very high activity area, possibly the highest in the USA. But it's all relative. Just because you live somewhere with 25% of that activity doesn't mean you can't be hit too.
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On Tue, 9 Oct 2012 09:01:14 -0700 (PDT), " snipped-for-privacy@optonline.net"

Aren't lightning rods grounded?
I thought it was the build-up of a positive charge on some high point that attracted the lightning, and the ground let the positive charge be neutralized from spare electrons in the earth. Hence the lightning wouldn't strike. ??

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wrote:

Not true at all. It just gives the lightning a better path to ground so the energy can take a straight shot and save the building.
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There are writings to that effect if you look. I don't think they know everything about lightning yet.
Greg

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I think what Micky may be referring to are some of the systems that claim to reduce lightning strikes through various means. Whether any of that has been actually proven to work, I don't know. But I think these systems are more than the typical lightning rods that have been installed on buildings for hundreds of years. The purpose of those conventional systems, as gfretw states is to provide a safe path for lightning if it does strike. And my guess would be that if one looked at two identical buildings, one with and one without lightning rods, the one with might have somewhat more strikes, because it has a mighty fine ground point high up in the air. Hence a bolt that might have instead gone to a nearby tree, winds up hitting the rod. So, you could have more strikes, but no damage, because the system conducts the energy to the earth. Whether any studies have been done on that, IDK.
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On 10/11/2012 7:04 AM, snipped-for-privacy@optonline.net wrote:

As I remember, there are 2 companies with other technologies than simple rods.
One presumably is more 'attractive' to lightning so you need fewer protection points.
The other allegedly discharges the cloud.
There are some good reasons the second approach will not work.
NASA tried one and it just worked like a conventional lightning rod.
One of the copmanies sued the NFPA (over NFPA780, the installation standard, or it might be UL). The lightning company lost the case.
Far as I know, the magic rods are not recognized by the industry.
There is disagreement over whether a sharp rod point is better than a dull one. The research that has been done shows little, if any, difference - with something like a 1/2" radius being slightly preferred.
(All that is from memory.)
Lightning rods are now called air terminals.
I agree with gfretwell.
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I think the concept with the "discharge the cloud" approach is that you put up a whole lot of lightning rods over the area to be protected. That is supposed to then provide a path for current flow between the cloud and ground that in turn lowers the potential difference. The obvious question is how much current can actually flow compared to the enormous capacity of the cloud? During a lightning strike you have an ionized path which provides good conductivity. And there is obviously a huge amount of energy to discharge. With just lightning rods and no actual strike to provide ionization my bet is that any discharge is going to be negligible and hence the rods would just serve as a lot of conventional rods.
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bud-- wrote:

There was a similar conflict in the 18th century, shortly after Ben Franklin invented the lightening rod. The conflict arose over whether churches should install them.
The controversy arose as follows: Even IF lighting rods worked, it would be clearly against God's will to install one. Churches in most of America, because of their steeples and bell-towers, were often the tallest buildings in the community and the prime target for a bolt from the grey. Here's how the controversy resolved itself:
The churches WITHOUT lightning rods eventually all burnt to the ground and the congregations had to move to churches who WERE defying God's will (or Thor's).
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wrote:

Couple of years ago, I got his with a surge from lightning. I have no idea where the actual strike was, but. . .
I have a detached garage. On the outside of the garage away from the house I have a two lamp spotlight mounted under the eave. There was a hole in the downspout that runs by it . Inside, the wire to the light plugs into a receptacle. I found pieces of the plug and receptacle five feet away from the box in the garage. One of the circuit breakers in the house on that buss was fried as well as my TV, receiver, and doorbell that are on that circuit.
The good news is, I was able to replace all the electrical parts for about $15. The better news is, the next night I had a new 47" flat screen HD TV.
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Years ago, there a loud crack nearby. Didn't notice anything until next day, my telephone modem would not work. After that I installed mov's on tele line.
Greg
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I was just thinking about the two or three ground rods near my service entrance. Not sure if there is a code stating things other than so many feet deep. I never really thought about it, by my grounds must be poor. They are close to the foundation, on the dry side of the house, and they might not even go below foundation, because of the landscape. I got another ground rod on other side of house off my aluminum porch roof, and iron railing. I know the light box ground is also connected to the same porch metals. A strike somewhere might cause significant current right through house. Another ground rod off elevated deck attached to metal rods in the air, plus cb antenna.
Separate garage, wired from house. There is no ground rods at garage, and no boxes. I think there might be a code for a ground, not sure. I have no box in garage, except for junction boxes. There is a ground rod connected to sheds metal roof.
Greg
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On 10/7/2012 7:50 PM, gregz wrote:

If using a rod the code wants it to be 25 ohms to earth, or you can install more than one with no resistance requirement. Easiest is to install 2 or more. I would guess the 3 rods are the power earthing system. I have occasionally driven a rod through the floor under the service. It avoids being close to the foundation and may be in moister soil. Rods are a crappy earthing electrode.

I would guess the rods off your metal roofs are crude lighting protection. It might prevent a fire at the point of the strike, but does not prevent major electrical damage.
For a lightning rod system, the earthing system must be bonded to the power earthing system. With high lightning currents to earth and resistance to earth plus impedance of down conductors there can be a very high voltage between down conductors and other metal. Metal within 6 feet of the down conductors may have to be bonded to them. Protection from a direct strike isn't simple.
The NEC wants metal support parts of an antenna connected to the power earthing system. And a protector(for coax just a ground block) that is connected to the power earthing system where the antenna lead enters the building. This will not protect from a direct lightning hit to the antenna.

The code wants a grounding electrode at a detached garage if fed by a feeder (with panel in garage), but it is not required if there is only a branch circuit to the garage.
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John Grabowski wrote:

Right. In sum, most MOVs (Metallic Oxide Varistor) act like a fuse in reverse.
And, like a fuse, an MOV only works once (or at best a few times).
The more expensive surge protectors do not use these MOVs but instead rely on electronic magic to take care of business, then reset, ready for the next surge.
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On 10/6/2012 10:37 AM, HeyBub wrote:

Nonsense.
MOVs have an energy (joule) rating. It is the energy the MOV can absorb in single event - one surge - that puts the MOV at its defined end of life (but still functional). If the energy hits are much smaller than the single event rating, the cumulative energy rating is much higher. For example a MOV might have a (single event) rating of 1,000J. If the individual hits are 14J the cumulative energy rating might be 13,000J. With high ratings a MOV may never fail.
That is particularly true for a plug-in protector. For a couple reasons the energy that can make it to the protector is very limited. An investigation found the maximum was 35 joules. That was with power service surges that were up to 10,000A (which, as in another post, is the maximum that has any reasonable probability of occurring).
Plug-in protectors with high ratings are not likely to fail. That is one reason why some of them have connected equipment warranties. If wired correctly they are very likely to protect from very near very strong lightning strikes.
(Neither plug-in or service panel protectors protect by absorbing a surge. But in the process of protecting they absorb some energy.)

According to the IEEE surge guide, "the vast majority (>90%) of both hard-wired and plug-in protectors use MOVs to perform the voltage-limiting function. In most AC protectors, they are the only significant voltage limiters." I don't know of any protection schemes for service panel protectors that do not use MOVs. They are so widespread because they have high energy dissipation capacity in a small package at relatively low cost.
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There is a lot of confusing information regarding these. There are very expensive models that don't have the capability of cheaper units. Some are listed as to be used at the equipment instead of the box. Some or most hast stranded leads make sure your breaker, if a attached, can handle stranded wire. The units I use as can be seen on some Holmes on Holmes. I had a previous model attached in my box. One day the during a storm the lights were going off on dim, etc, bang I heard downstairs at the box. Breaker tripped, unit blew out through it's mounting hole. Trying to get free replacement, for some reason didn't qualify. I order new unit, which had upgrade rating to 150000 amps. Good to go.
http://www.drillspot.com/products/1383845/Supco_SCM150_Surge_Protector
Greg
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If you order this, it will come from Grainger, which at granger costs more.!!
Greg
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I did not have a near lightning strike during this episode. I imagine the spike came from somewhere. It might even originated from my equipment at home, if that's possible, or some other house or factory. I had a strike this summer 100 foot from house. Nothing I could see in house that had any effect.
Greg
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wrote:

Dale-Electric.com has a similar Ditek unit for more like $35-40.
I believe it is part of the listing standard that all regular circuit breakers accept stranded wire. Just be sure it is in the range of acceptable sizes.
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