Share grounding rod in PV/Mains hybrid?

[Gdwats]

It is sinking in, thank you. I think i was concerned about my general system grounding, and not thinking about lightning protection. But it sounds like I may have both, to a degree, with the dual rod setup depending on where lightning strikes.

[max2k]

The odds of me understanding grounding configurations are about as good as me being struck by lightning. How can all my stuff be grounded to a single point when that point itself is bonded to another point, the second rod, 6 feet away. Unless the entire 6' x 8' bonded structure is considered one point. What is the "point"?

take a look at the screenshot posted earlier. When lightning strikes it creates concentric circles around with equivalent potentials, pretty much like normal map shows those lines of the same heights. Now if you happen to drive your rods between any of those 2 lines you'd get difference in potential in other words voltage in the range of possibly tens of kV. Solution is simple- bond those 2 rods with wire so the current 'equalizing' those kVs would flow through that wire and the wire will 'tie' up 2 rods closer in potential. Your equipment can be connected anywhere to this 'system' just make sure it's a single point. In case of a strike equipment will get under that point high potential but since it's the only point all equipment will be under the same tens of kVs potential (0 difference) and will remain safe.

As opposite to this consider running separate wires from each of your rods and connecting them to your equipment. In case of the strike equalizing current will come to your equipment first and then go back to the second rod. This is dangerous as it can create significant voltages along its way now inside/on the case of your equipment. We're talking of short burst of current in possibly kA range capable of creating voltage spikes in kV range.

[Gdwats]

The odds of me understanding grounding configurations are about as good as me being struck by lightning. How can all my stuff be grounded to a single point when that point itself is bonded to another point, the second rod, 6 feet away. Unless the entire 6' x 8' bonded structure is considered one point. What is the "point"?

[max2k]

I see, that is what i have, but nothing I've done is grounded or connected in any way, to the house. Yes, the bonding ground wire is awg4, a but overkill.

It's not the presence of the house is what's important but non 0 distance between the rods- any such distance would make rods under different potential during the strike due to potential gradient (those concentric circles on the graphic). Then if both wires coming into anything you might get tens of kV difference between them. Bonding directly avoids this problem and all your equipment gets under the same potential being connected to a single point.

[Gdwats]

Here's the graphic showing bringing in Lightning to your house

If you have a heavy ground wire in a trench, connecting the 2 electrodes, that provides a easier path, and the lightning goes around your house (mostly)

GroundingElectrode_MHolt.png

I see, that is what i have, but nothing I've done is grounded or connected in any way, to the house. Yes, the bonding ground wire is awg4, a but overkill.

[Gdwats]

Yes, one 8' rod bonded to the other 6 feet away with awg4 grounding wire from top of one rod to 18" from top of other. All equipment is then grounded to just the one rod, and all is now covered up.

[Mike90250]

Here's the graphic showing bringing in Lightning to your house

If you have a heavy ground wire in a trench, connecting the 2 electrodes, that provides a easier path, and the lightning goes around your house (mostly)

GroundingElectrode_MHolt.png

[max2k]

Watched video. Left me confused, and didn't apply to a non house instal really. Left me thinking my 2 bonded rod ground was dangerous.

depends how that bond is made - if it bonds 2 rods together with dedicated wire and then the rest of your equipment connected to that at 1 point it's OK but if both of them are connected to your system with individual wires it is not. Lightning is very fast event (in uS range) with very high current reaching hundreds of kA. Those hundreds of kA going to the ground through 'resistors' in Ohms range create hundreds of kV voltages. Due to short times inductance of those wires matter too- you can have DC connection which presents high impedance at those short times meaning that path will be simply 'ignored' by lightning charge and it will find some shorter alternative nearby.

[Gdwats]

Watched video. Left me confused, and didn't apply to a non house instal really. Left me thinking my 2 bonded rod ground was dangerous.

[Gdwats]

Thank you all. My stuff is all isolated and safe. Nothing is tied to the house. Just a fused a.c. inverter inside. Will watch video. I'll ignore what I discovered. Will be moving again soon.

[neweclipse]

NEVER allow ANY of your body parts to get in between a 'dangling' service ground wire and earth and/or grounded electrode, it can KILL!!!
It is an 'open circuit' and may have potiential voltage that will cause you to 'hung up' and unable to leave go once in contact with it.

Call an Expert!!!

[Mike90250]

Grounding is a sticky wicket and I'm not ever giving any advice on it, because it is so important, and there are so many regions that have different requirements, But I can say go to your building office, explain what you have, what you discovered, and ask what THEY want you to do to meet their current rules.

I don't think bringing lightning into your home through a panel is a good idea, but some areas still have that in their code, and I can only throw my hands up in the air.

Watch the Mike Holt videos on Grounding and Lightning and you will start to get an idea of whats state of the art.

[max2k]

Not what I asked

I doubt what you're doing is legal and as such any path you take will be as good as any other- you're on your own.

[Gdwats]

Not what I asked

[max2k]

Wow, again. I thought a system ground was required, so I drove 2 8' rods in the ground 6 feet apart connecting the first to the second with wire running from top of one to 18" down on the second. Attached grounds from system and hurried the whole thing up. Then I saw a single grounding rod for the house sticking up with a corroded, broken off ground clamp dangling there in pieces. Should I call the owner? Should I just re attach it? Should I attach it to my rod(s).

ps OP: not meaning to flood your post. Thought pertinent.

if the owner is not someone close to you I'm surprised they're OK with any alterations you're doing especially on the electrical side. One thing is to call and complain about disconnected grounding wire and completely different is to connect your system to their grounding rod without their consent. Even home owners need to get that 'consent' from local AHJ as insurance / neighbors want to be sure they are not burning the whole block down as a result of their 'improvements'.