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Roof Top Grounding Sanity Check Please

Do those air terminals really work?
The van den Graff effect is real, and faraday cages really work.

Lightning rods do work some of the time- there’s a certain point where the sheer power of a lightning strike doesn’t care about a dinky little cable
 
And, multiple ground paths are not an issue.
It's actually a good thing to have redundancy.
I disagree.

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In addition, studies have shown that adding a ground electrode at a generator is significantly more likely to cause equipment damage for this reason.
 
I disagree.

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In addition, studies have shown that adding a ground electrode at a generator is significantly more likely to cause equipment damage for this reason.
I didn't say multiple ground rods.
Multiple conductor paths.
Auxiliary ground rods are allowed by the code, but not required. (I wish that they weren't allowed) but, if Auxiliary ground rods are installed. They are required to be connected (by a conductor, usually a #6 copper minimum) to the grounding system.
 
I have also determined that I wouldn't add a second rod, at the array. I don't want my array to attempt to be a lightning protection system.
 
I didn't say multiple ground rods.
Multiple conductor paths.
Auxiliary ground rods are allowed by the code, but not required. (I wish that they weren't allowed) but, if Auxiliary ground rods are installed. They are required to be connected (by a conductor, usually a #6 copper minimum) to the grounding system.
OK. Sorry. I misunderstood.

I may still be misunderstanding the statement but multiple paths in the Equipment Grounding Conductor system can also be a problem if they create a ground loop.

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Industrial sights are notorious for radio noise.
Because of all of the grounding.
I mean, well, everything is metal.
Metal boxes and equipment, mounted on building steel. Rigid conduit, between all of it. And, an equipment grounding conductor pulled through everything. And bonded to everything, along the way.
 
Industrial sights are notorious for radio noise.
Because of all of the grounding.
I mean, well, everything is metal.
Metal boxes and equipment, mounted on building steel. Rigid conduit, between all of it. And, an equipment grounding conductor pulled through everything. And bonded to everything, along the way.
Yup. Loops of all sizes are all over the place in even light-industry settings (and some of them are easily preventable). This means there are lots of opportunities for one of the loops to resonate at a frequency that interferes with something else. It is not always possible to eliminate all ground loops. In fact, in some cases code pretty much forces you to create them. (Example: A metal outlet box screwed to a metal building structure that is already grounded must have the equipment Grounding Conductor bonded to the box..... Boom! A ground loop is created. ) However, where you can avoid loops, you should. This is typically a lot easier in a home system than in an industrial setting.

Note: This is made worse if there are multiple Neutral-Ground bonds. Almost by definition, this creates a loop involving the ground and has an active current through the loop that can carry noise and pump the resonant frequencies of the loop.

Now add to the above the fact that we are dealing with inverters that, by design, switch very large currents. This is almost the definition of an electrical noise generator.

Sometimes there is a significant impact but no one realizes it is RFI noise. Many modern radio systems like WiFi have error detection and correction. This means that if the RFI interferes with a packet of data it gets resent. This is great because the system works through errors, but it can significantly reduce the throughput of the system....and we just chalk it up to a "weak signal" In addition, we have all experienced WiFi dead spots and chalked it up to a weak signal. However, it can be a strong WiFi signal but RFI can be interfering beyond the capability of the system to correct the errors.
 
Lightning protection and equipment grounding are two different things.
An airport rotating beacon on a 60ft metal tower has 2 "grounds". The ground from the rotating light fixture on the tower ties into the electrical systems egc as usual. The lightning rod on the tower is bonded to the tower and then to the steel in the concrete foundation and then a separate rod. The only location the 2 systems are bonded is by association of the fixture mounted to the tower. Solar arrays , navigational towers etc...at the airfields wired the same way. Even the runway lights and signs each have their own 10ft x 3/4" rod cadwelded to base. Multiple ground rods installed with proper design are not a problem
 
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