Quote:
Originally Posted by spinner1001
You are talking about whether there is an effect of LPS. I am talking about the effect size of LPS. Knowing an effect and knowing an effect size are very different. For instance, do LPS lower the average likelihood of a lightning strike on a single-family home by 10% or 90%. This is an important question for insurance companies, mortgage lenders, home owners, and so on.
Effect != Effect size
If you have references to empirical evidence about the _effect size_ (i.e., magnitude of the effect) of LPS on structures in any quality scientific journal, please provide the references (i.e., name of journal, volume, issue, author, date) and I will read them. (A book is not a quality scientific journal.)
I don’t doubt there is an effect of LPS. I have a LPS. I would like to know the empirical evidence of the effect size of LPS on homes. I am skeptical strong evidence of the effect size exists.
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I'm not aware of any studies that claim their results showed having a LPS lowed the average likelihood of a lightning strike on a single-family home by "X" percent but it's a good point and will look into it.
Since lightning is unpredictible and you would have to have some system installed to monitor when a home with a LPS was actually hit, my "guess" is there is little data on this. The current "thinking" is that a LPS will limit or prevent significant damage to the structure if a lightnig strike occurs vs preventing a strike. As mentioned there are studies underway on systems to "prevent" lightning strikes as well.
Len Hathaway, the founder and leader of the Villages Lightning Study Group has a device installed on his LPS that will trigger when lightning strikes his system. No hits recorded yet. Unfortunately this device is expensive. Also, when a home with an LPS is hit, a thorough investigation would be needed to make sure the LPS was installed and maintained properly to weed out any faulty installations. As part of the maintenance, you need to check the validity of the grounding system on the LPS. I have a meter to check this. Typically, an LPS ground rod is driven 10-20 feet into the earth to get a good ground meaning a ohm rating low enough as specified by UL. In my home, Triangle had to drive the ground rods down 30 feet to get a ground that was in tolerance with the UL specification. Fortunately, the certified installers will do what is needed to get a good ground or the system will be ineffictive. We do have a case where a ground rod lost it's effectiveness for some unknown reason and had to be replaced. Fortunately, three to four ground rods are typically installed and every air terminal (lightning rod) has two paths to ground.