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Old 11-23-2013, 01:23 PM   #31
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Residential grounding


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Originally Posted by avengerki View Post

A ground on a house is also there to provide a path for lightning to be redirected along a safe path and prevent/minimize damage to a persons house.
And this is the only statement you posted that is required by the NEC, like i said, pretty useless IMO….. The only problem with this theory, is that it's pretty hard to prove that a house didn't get destroyed by having a ground rod installed…..


What i'm saying is, I doubt statiscally you could show better or worse outcomes when it comes to lightning strikes and structures having a 8' grounding rod in the dirt next to that structure…..


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Old 11-23-2013, 01:30 PM   #32
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Residential grounding


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While a ground is not needed for an electrical system to function, a ground is there to allow a safe transmission point for unwanted electrical energies. If there is no place for these energies to be dissipated it can lead to fires and electrical shocks.

Each grounding rod you add increases the area and conductivity to allow the dissipation of the energy. In order to be able to see the change you would need to use a megger to test the ground, this is what is done during those inspection. Generally the drier the climate the more grounding rods would be needed, or few spread out rods and more longer rods that go deeper in the ground. There is actually a fair amount of science that goes into grounding.
None of this is relative to a residential structure…..
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Old 11-23-2013, 01:48 PM   #33
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Residential grounding


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What i'm saying is, I doubt statiscally you could show better or worse outcomes when it comes to lightning strikes and structures having a 8' grounding rod in the dirt next to that structure…..
Nope but I have seen the damage to a residential structure that did not have any grounding. And that same structure after multiple strikes with proper grounding.

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None of this is relative to a residential structure…..
Most of that goes into the theory and purpose. In the electronics of today they rely heavily on that ground to be there.
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Old 11-23-2013, 02:06 PM   #34
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Residential grounding


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Nope but I have seen the damage to a residential structure that did not have any grounding. And that same structure after multiple strikes with proper grounding.
Could have had the same damage with a ground rod… we will never know…

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Most of that goes into the theory and purpose. In the electronics of today they rely heavily on that ground to be there.
A surge protect, yes…. everything else, blah…. since most electronics only have a two wire cord installed on them…..and when they do have a 3 wire cord, they are only bonding the metal frame of such appliance….
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Old 11-23-2013, 02:14 PM   #35
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Residential grounding


an ungrounded system with proper bonding of metallic surfaces is infinitely safer than a grounded system with bad bonding.
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Old 11-23-2013, 03:11 PM   #36
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Residential grounding


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an ungrounded system with proper bonding of metallic surfaces is infinitely safer than a grounded system with bad bonding.
I concur, people really do not understand bonding vs grounding….
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Old 11-23-2013, 03:13 PM   #37
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Residential grounding


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Originally Posted by avengerki View Post
While a ground is not needed for an electrical system to function, a ground is there to allow a safe transmission point for unwanted electrical energies. If there is no place for these energies to be dissipated it can lead to fires and electrical shocks.

Each grounding rod you add increases the area and conductivity to allow the dissipation of the energy.

THere are a lot of variables in this, soil type, temperature of the soil, placement of the driven electrodes spacings and location.

Quote:
In order to be able to see the change you would need to use a megger to test the ground, this is what is done during those inspection. Generally the drier the climate the more grounding rods would be needed, or few spread out rods and more longer rods that go deeper in the ground. There is actually a fair amount of science that goes into grounding.
A megger is not utilized to measure ground resistance. A 4-point earth ground resistance tester is utilized to determine the resistance of the soil and aid in designing a grounding electrode system. Hardly something that is done for residential or commercial electrical distribution systems. Once the grounding electrode system is installed and prior to connections to the electrical distribution system a 3-point Earth ground resistance tester is utilized to determine the actual resistance of the system and this is not a simple test. Even this reading is actually only an average because as noted weather will affect the resistance

Quote:
A ground on a house is also there to provide a path for lightning to be redirected along a safe path and prevent/minimize damage to a persons house.
While this is true, basically the typical residential grounding electrode is installed marginally - poor connections, the grounding electrode conductor is routed with sharp bends, a number 6 awg to handle Mother Natures finest strikes, no maintenance or after installation inspections. And the biggy the unknown resistance of the two rods?
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Old 11-23-2013, 03:17 PM   #38
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Residential grounding


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While this is true, basically the typical residential grounding electrode is installed marginally - poor connections, the grounding electrode conductor is routed with sharp bends, a number 6 awg to handle Mother Natures finest strikes, no maintenance or after installation inspections. And the biggy the unknown resistance of the two rods?
#6 is used because the earth is such a terrible conductor to begin with, i'm guessing its 50x oversized to begin with…
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Old 11-23-2013, 03:18 PM   #39
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Residential grounding


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an ungrounded system with proper bonding of metallic surfaces is infinitely safer than a grounded system with bad bonding.
Ungrounded systems are very safe, as the potential from a phase conductor to ground is low (depending on the capacitance coupling of the system). Have a ground fault no problem, no arcing ground faults and the devastating damage seen in 480/277 VAC systems, no loss of power due to tripping circuit breakers.

Second fault and there are some real issues

There are some issues with over voltages on ungrounded systems hence the use of resistance or impedance grounded systems, where you limit the fault current to low levels, typically (in my experience) to under 25 amps.

Of course these systems are limited in use by NEC rules (and need to be).
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Old 11-23-2013, 03:20 PM   #40
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#6 is used because the earth is such a terrible conductor to begin with, i'm guessing its 50x oversized to begin with…
Strictly for lighting and the high frequency and high voltage a flat braided conductor with no bends has been found to work best.
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Old 11-23-2013, 03:21 PM   #41
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Strictly for lighting and the high frequency and high voltage a flat braided conductor with no bends has been found to work best.
Sure if the conditions are perfect, which again, we shall never prove because of the uncertainties of lightning to begin with…

In other words, ground rods are like paying for car insurance, you may never have to use this insurance, but when you do, you still don't know what it's going to cover…. lol…
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Old 11-23-2013, 03:36 PM   #42
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Residential grounding


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Sure if the conditions are perfect, which again, we shall never prove because of the uncertainties of lightning to begin with…

In other words, ground rods are like paying for car insurance, you may never have to use this insurance, but when you do, you still don't know what it's going to cover…. lol…
We have installed massive grounding electrode systems and when installed properly, tested to certain specification, and maintained will minimize damage from lighting strikes, BUT very few facilities can and do go to this extreme.
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Old 11-23-2013, 04:35 PM   #43
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Residential grounding


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We have installed massive grounding electrode systems and when installed properly, tested to certain specification, and maintained will minimize damage from lighting strikes, BUT very few facilities can and do go to this extreme.
You cannot prove that statement, but hey, you are making money selling something to someone that wants this warm happy feeling… I applaud you.
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Old 11-23-2013, 11:05 PM   #44
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Residential grounding


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THere are a lot of variables in this, soil type, temperature of the soil, placement of the driven electrodes spacings and location.
Yes there are. Getting a good ground in any given location can be a pain. I have spent anywhere from an hour to a week in some locations. Even had to go and improve the grounding system when weather conditions and the ground were drier.

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A megger is not utilized to measure ground resistance. A 4-point earth ground resistance tester is utilized to determine the resistance of the soil and aid in designing a grounding electrode system. Hardly something that is done for residential or commercial electrical distribution systems. Once the grounding electrode system is installed and prior to connections to the electrical distribution system a 3-point Earth ground resistance tester is utilized to determine the actual resistance of the system and this is not a simple test. Even this reading is actually only an average because as noted weather will affect the resistance
A Megger is the same thing as the 3-point Earth ground resistance tester. All I could remember was Megger and not what the resistance test was actually called since everyone I used to work with called it the same thing, and in my current job the call it the same thing. This test can also be performed after connection to the electrical distribution system.

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Originally Posted by Know A Little View Post
While this is true, basically the typical residential grounding electrode is installed marginally - poor connections, the grounding electrode conductor is routed with sharp bends, a number 6 awg to handle Mother Natures finest strikes, no maintenance or after installation inspections. And the biggy the unknown resistance of the two rods?
I completely agree, except for the unknown resistance of the two rods. When you are testing the ground you are finding out the resistance in the whole system including the rods. I had seen on my grandparents home a ground rod that was corroded completely through.
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Old 11-23-2013, 11:19 PM   #45
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Residential grounding


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Could have had the same damage with a ground rod… we will never know…
You fail to pay attention to everything I said. The house prior to the proper grounding had been struck by many lightning strikes. Each time it was struck there was damage, the last strike they had before getting a proper ground caused quite a bit of damage. After they had the proper grounding they still were getting struck by lightning but were not receiving any damage. The house was struck more than 8 times within a 3 year stretch, I always thought it fairly weird but that house just seemed to be a magnet.

Having a good and proper ground is like an insurance policy. You may think it is completely worthless until you needed one and didn't have it.

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