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No earth grounding?

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sunsurfer

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This applies to off-grid setups and "earth" grounding, not chassis grounding. Not that I like to take a bath with my toaster.

I was thinking about lightning protection. The idea is to NOT ground things to earth but instead isolate from earth. The idea is to not help initiate any lightning leaders from ground source. I have some panel leads that are ran in poly tubing on the surface. Not sure how much poly insulates, have to look into that. Wondering if buried would be better or not.

Only thing is, I want to run some surge arrestors and I am not sure if those work off earth grounding or not.

Thoughts? Question is, would earth grounding make lightning strikes more likely? Why earth ground if you are not on the power grid?
 
Let me start you off, until the usual "know it all" shows up.
I suggest spending some time, researching this matter. Only because it will he YOUR decision, in the end.
As I understand, it is unlikely for you to make lightening strike any more frequent than nature. The issue with solar and lightening is, a direct strike will toast just about anything anyway. It's the stray effects of energy, that travels on conductive materials. This means that even, non connected items may have enough electricity to fry some components. That is why we connect to ground (earth).
And, yes.... lightning protection uses ground to dissipate the energy.
Good luck, good day.?
 
I certainly don't "know it all", but have dealt with grounding/lightning protection for years-mainly communication towers and cell sites.

Grounding the panels is for personal protection, not lightning protection although lightning protection does require good grounding-so they are related. In my experience, surrounding objects like trees and structures are usually much taller than say a ground mount array and will likely be more attactive targets for the strike.

In the usual installation, grounding the panels isn't going to increase the probability of the array being struck. We're talking a path length of thousands of feet if not miles, so the strike doesn't even see the few feet that an ungrounded array is mounted of the ground. A couple of inches of plastic pipe wall or wire insulation won't make a difference.

Again, grounding the panels is a safety matter and is a NEC requirement.

Polyphaser used to have a grounding guidance document that was damn excellent. You might search around for it. Also, Motorola FNE standards is a great reference if you want to learn more about this stuff!

Bottom line, ifthe array isgoing to be struck, it will be struck-grounded or not. If it happens, there's gonna be damage.
 
The surge protection device takes any overvoltage and dumps it to earth ground.
The PV panels need to be tied to earth ground at least at the SCC or where it is tied in at the main AC breaker panel.
My array frame is steel pipe, so the PV panels are earth grounded there as well as through the ground wire in my AC breaker panel.
I do not have a ground rod at the PV array, just at the main AC breaker panel.
I have a SPD at the outside PV disconnect, and one inside at the junction box where the wires penetrate the wall.
My cabin is completely offgrid.
 
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My steel ground mount is earth tied (obviously) and there is a ground rod to a #6 solid copper to a pannel frame clamp and then frame jumpers to ground the pannel frames.

The hope is if the array is struck by lighting that the surge goes to ground before it goes to my equipment. (i have little hope that will protect my inverters but its better insurance than no frame panel grounding)

Buss grease monkey had all his solar fried by a lighting strike on his metal building.
I dont know what kind of grounding sitiuation he has, he typically has fairly DIY aproach to his solar installs. (aka it may not always be the "right" way)
 
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I started a thread about this topic a few weeks ago. My thought was if it is a small system on a structure that is not naturally earth grounded there might be some benefit to not earth ground. Naturally grounding meaning on a pad with rebar, metal plumbing, metal building etc. From my research it appears to be ok, but the standard practice is to earth ground. WProwse did a vid about grounding and makes a brief comment about this in the vid below.

 
I'll be a know-it-all if you want. Having lived in places where they didn't have a neutral-ground bond you are going to have to understand that you are going to get shocked a lot. You can reduce the chances of this killing you by putting a GFCI on your main breaker. If it is working it will trip a lot.

But, if you are trying to keep the system "isolated" from ground for lightning protection you are going to have a lot of work ahead of you. You will need to insulate all electrical enclosures and only use double-insulated appliances. You don't run any ground wires, and you need to make sure nothing creates an incidental ground. If you really want to protect from lightning, that isolation from ground needs to be sufficient to withstand lightning flashover, because your wiring is likely going to be a lower impedance path than a 2x4, even with insulation on it.

If you really want to protect yourself from lightning in an off-grid situation with high lightning risk, the best way to do it is to just have steel poles close-ish to your house that become the highest point. This diagram might help explain how hard it is to make that work; you need to keep a 150' radius ball from being able to touch anything on the house without first hitting your metal pole.

1689386233621.jpeg
 
The main benefit of an earth ground is to handle the static build up. Is that substantial on a small structure and system? From my research it is more of a factor with a grid connection. The video below was the reason I started to look a the benefit for off grid. It is not the part of grounding the sub panel but his description of how the earth ground functions.

 
I would tend to use an earth ground for a permanent structure even if off grid. +1 for a main GFCI or on most branch circuits.

Consider a separate lightning rod mounted high and away from the system with a direct heavy strap to ground. Seen these on some farm houses out in the mid-west.

For best info I recommend to ask Mike. https://forums.mikeholt.com/forums/bonding-and-grounding.22/.
 
Madco said:
I certainly don't "know it all", but have dealt with grounding/lightning protection for years-mainly communication towers and cell sites.

Grounding the panels is for personal protection, not lightning protection although lightning protection does require good grounding-so they are related. In my experience, surrounding objects like trees and structures are usually much taller than say a ground mount array and will likely be more attactive targets for the strike.

In the usual installation, grounding the panels isn't going to increase the probability of the array being struck. We're talking a path length of thousands of feet if not miles, so the strike doesn't even see the few feet that an ungrounded array is mounted of the ground. A couple of inches of plastic pipe wall or wire insulation won't make a difference.

Again, grounding the panels is a safety matter and is a NEC requirement.

Polyphaser used to have a grounding guidance document that was damn excellent. You might search around for it. Also, Motorola FNE standards is a great reference if you want to learn more about this stuff!

Bottom line, ifthe array isgoing to be struck, it will be struck-grounded or not. If it happens, there's gonna be damage.
Click to expand...
I was not referring to you at all. Good imput!!!
 
Nothing in the NEC pertains to protecting against direct lightning strikes, and I doubt the presence or lack of a ground would make a difference. If you have metal like a solar panel array, then even if it's floating lightning would rather go through it and jump to ground than strike the ground next to it through the air.

NFPA 780 covers lightning strike protection and the TL;DR is you use lightning rods for that, not your electrical equipment.
 
I can only speak from experience, and grounds can be weird, but on balance I'd say if you can drop a couple ground rods and ground it, do it.. When I was in the sand hills of NC working in IT, we had a few sites where we were literally frying the gear every few months/year. We put external modems in as fuses, which helped and we had UPS's which helped, but we were still constantly replacing equipment. In every case there were serious issues with the building grounds, and adding actual ground rods near the communication and power feeds resolved the problems. The primary issues were things that were never grounded, or where they were grounded to copper piping that was later replaced with plastic. Here in Arizona, my sister was replacing her HWH every 2 years, brand new house, the copper piping aournd the tank inlets/outlets turned into a green and white flower after about 6 months, After the 3rd go around, they were complaining at a get-together, I went in to the utiility room and the HWH was grounded to ... The copper feed pipe, that had been cut to put in a soft-water loop, with plastic pipe. I went on the other side of the outside wall, dropped a ground rod, tied it in, and all the problems went away.

This is all somewhat anecdotal, but the first thing I did before connecting any of my solar was drive an 8ft ground rod, and make sure everything was grounded. I'll be driving the second one into the incredibly hard soil here, to meet code, over the next week or two, but after all my experience dealing with ground problems, I think it's easier just to save the hassle and put in a good ground.
 
ksmithaz1 said:
I can only speak from experience, and grounds can be weird, but on balance I'd say if you can drop a couple ground rods and ground it, do it.. When I was in the sand hills of NC working in IT, we had a few sites where we were literally frying the gear every few months/year. We put external modems in as fuses, which helped and we had UPS's which helped, but we were still constantly replacing equipment. In every case there were serious issues with the building grounds, and adding actual ground rods near the communication and power feeds resolved the problems. The primary issues were things that were never grounded, or where they were grounded to copper piping that was later replaced with plastic. Here in Arizona, my sister was replacing her HWH every 2 years, brand new house, the copper piping aournd the tank inlets/outlets turned into a green and white flower after about 6 months, After the 3rd go around, they were complaining at a get-together, I went in to the utiility room and the HWH was grounded to ... The copper feed pipe, that had been cut to put in a soft-water loop, with plastic pipe. I went on the other side of the outside wall, dropped a ground rod, tied it in, and all the problems went away.

This is all somewhat anecdotal, but the first thing I did before connecting any of my solar was drive an 8ft ground rod, and make sure everything was grounded. I'll be driving the second one into the incredibly hard soil here, to meet code, over the next week or two, but after all my experience dealing with ground problems, I think it's easier just to save the hassle and put in a good ground.
Click to expand...
One caveat being all ground rods/electrodes need to be connected together, but your experience mirrors my own.
 
We should evaluate this from the most common use which is a grid connected service and see how the benefits carry over. Then evaluate the utility of each for an off grid application.

From my understanding there might be three or four. 1. Static electricity build up in the system, 2. Lightening-not a direct hit, but near by or down line grid components, 3. A loose hot in the earth, 4. Excessive current from a short can go to ground if there is a source earth ground for it to return to ie. the grid transformers earth ground. This is a high resistance path and will not carry much amperage.
 
timselectric said:
Incorrect
The main purpose of grounding to anything is to keep it from shocking you.
Click to expand...
It can be and is both. Utility companies in the early days of the grid started grounding their systems because huge voltages were building up on the long transmission lines. Generator mechanics at the central stations were being blasted just standing next to the equipment.
 
CoolWill said:
It can be and is both. Utility companies in the early days of the grid started grounding their systems because huge voltages were building up on the long transmission lines. Generator mechanics at the central stations were being blasted just standing next to the equipment.
Click to expand...
This isn't a large grid generator.
 
timselectric said:
Incorrect
The main purpose of grounding to anything is to keep it from shocking you.
Click to expand...

We are not talking about grounding in general, but a very specific type and how it benefits an off grid application. Do you have specific examples?
 
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