Grounding roof mounted system - confused

[tinyt]

View attachment 166940

Apologies if this is off topic, but this picture reminds me of what the city inspector asked me to do when I moved the service entrance to another wall of my previous residence.
I grounded the main panel to a ground rod as shown but the inspector asked me to connect the earthing ground to the house water copper pipe instead. Even my current residence has the earthing ground connected to the house water copper pipe, no ground rod.
Is this a code requirement (electrical and plumbing)?

 

[Jim in Florida]

Apologies if this is off topic, but this picture reminds me of what the city inspector asked me to do when I moved the service entrance to another wall of my previous residence.
I grounded the main panel to a ground rod as shown but the inspector asked me to connect the earthing ground to the house water copper pipe instead. Even my current residence has the earthing ground connected to the house water copper pipe, no ground rod.
Is this a code requirement (electrical and plumbing)?

Code gives several ways to make the earth ground. Most common in my area is two 8’ grounding rods connected at least 6’ apart.
NEC article 250 covers the ways to ground and bond.

 

[timselectric]

Well, shoot, now I'm confused... I have an off grid shed with a 120V Victron Multiplus. Outside the shed, I have a ground rod, and the Multiplus is connected to that ground rod at the grounding connection (lower right of unit as I recall).

It's not an off grid shed, because it has a grid source from the garage.
Everything should be connected to the existing grounding system at the garage.
The ground rod at the shed is an auxiliary ground rod. While allowed (but not recommended). If installed , it must also be connected to the existing grounding system.

1) Should I also connect the solar panel frames to THAT SAME ground rod, and to ONLY THAT ground rod? I was going to connect the frames to a separate ground rod, just for lightning/static protection, but now I'm thinking that's a bad idea.

One grounding system for everything.

2) Should the SCC be connected to that same ground rod?

You can.
Once you connect this auxiliary ground rod to the existing grounding system. It becomes a part of the grounding system. And can be used as a connection point for other equipment grounding.

3) Should the negative bus bar of the system be connected to that ground rod?

No, this is not a mobile installation.

4) Is there anything else in the system that should be connected to that ground rod?

Nothing has to be connected to this auxiliary ground rod. The only requirement for this auxiliary ground rod. Is that it must be connected to the existing grounding system.

 

[timselectric]

Apologies if this is off topic, but this picture reminds me of what the city inspector asked me to do when I moved the service entrance to another wall of my previous residence.
I grounded the main panel to a ground rod as shown but the inspector asked me to connect the earthing ground to the house water copper pipe instead. Even my current residence has the earthing ground connected to the house water copper pipe, no ground rod.
Is this a code requirement (electrical and plumbing)?

This is where people get confused. You are not grounding your system, by connecting it to the earth.
You are grounding the earth, by connecting it to your grounding system.
The grounding system is created by the N/G bond in the main service panel. And everything else is connected (bonded) to it.
Anything that you can touch and can conduct electricity. Should be connected (bonded) to the grounding system for personal safety.
This includes (but isn't limited to) water service, gas service, the earth, building structure, equipment enclosues and raceways.

 

[tinyt]

This is where people get confused. You are not grounding your system, by connecting it to the earth.
You are grounding the earth, by connecting it to your grounding system.
The grounding system is created by the N/G bond in the main service panel. And everything else is connected (bonded) to it.
Anything that you can touch and can conduct electricity. Should be connected (bonded) to the grounding system for personal safety.
This includes (but isn't limited to) water service, gas service, the earth, building structure, equipment enclosues and raceways.

So in Florida, assuming they have metal water supply pipe, it is possible for them to get zapped by malfunctioning electrical kitchen equipment if they touch both equipment and faucet at the same time. I am totally confused.

Code gives several ways to make the earth ground. Most common in my area is two 8’ grounding rods connected at least 6’ apart.
NEC article 250 covers the ways to ground and bond.

 

[timselectric]

So in Florida, assuming they have metal water supply pipe, it is possible for them to get zapped by malfunctioning electrical kitchen equipment if they touch both equipment and faucet at the same time. I am totally confused.

If the kitchen equipment is not properly grounded, yes.
Not specific to only Florida.
Also not specific to metal water supply pipe.
The water is conductive.


Edit: actually, no.
Because the kitchen outlets should be GFCI protected.

 

[Madcodger]

It's not an off grid shed, because it has a grid source from the garage.
Everything should be connected to the existing grounding system at the garage.
The ground rod at the shed is an auxiliary ground rod. While allowed (but not recommended). If installed , it must also be connected to the existing grounding system.

@timselectric

Hi Tim,

First, thank you for your reply. Greatly appreciated. For this shed, and I guess or any building that operates with an AC input only part of the time, it's almost like having "shore power" in that the AC input occurs only intermittently, as if it were connected with an extension cord. Does that change anything?

In my case, the AC line is literally plugged into an RV outlet box on the side of the building, with the other end of that AC line then plugged into an outlet on the outside of the garage. It really is much like an extension cord in that sense. When that occurs, there is certainly a ground wire connected back to the grid source, at the garage. But what about the rest of the time, when that AC line is just completely disconnected (i.e., no "shore power")? When that happens, which is often, there is no connection back to the garage. My thinking has been that when that is the situation, the Multiplus is making the ground-neutral bond, and that the grounding rod beside the building is serving a useful purpose related to that ground, because without that AC line plugged in, the Multiplus is not connected to another AC "system". In other words, that the grounding rod is serving the same purpose as the grounding rod in any building, as the system wouldn't be connected to another AC ground when no AC line is present. Am I misunderstanding that? If I did not have that grounding rod at the building and the "shore power" AC line isn't plugged in, would things still operate as safely?

Thanks.

 

[tinyt]

If the kitchen equipment is not properly grounded, yes.
Not specific to only Florida.
Also not specific to metal water supply pipe.
The water is conductive.


Edit: actually, no.
Because the kitchen outlets should be GFCI protected.

So, if the homeowner's old house has no GFCI can I assume that our city makes it safer by requiring our copper water supply pipe to be connected to the utility system ground?

 

[timselectric]

@timselectric

Hi Tim,

First, thank you for your reply. Greatly appreciated. For this shed, and I guess or any building that operates with an AC input only part of the time, it's almost like having "shore power" in that the AC input occurs only intermittently, as if it were connected with an extension cord. Does that change anything?

In my case, the AC line is literally plugged into an RV outlet box on the side of the building, with the other end of that AC line then plugged into an outlet on the outside of the garage. It really is much like an extension cord in that sense. When that occurs, there is certainly a ground wire connected back to the grid source, at the garage. But what about the rest of the time, when that AC line is just completely disconnected (i.e., no "shore power")? When that happens, which is often, there is no connection back to the garage. My thinking has been that when that is the situation, the Multiplus is making the ground-neutral bond, and that the grounding rod beside the building is serving a useful purpose related to that ground, because it's not connected to another AC "system". In other words, that the grounding rod is serving the same purpose as the grounding rod in any building, as the system wouldn't be connected to another AC ground when no AC line is present. Am I misunderstanding that? If I did not have that grounding rod at the building and the "shore power" AC line isn't plugged in, would things still operate as safely?

Thanks.

As a permanent installation (not mobile or portable), it really shouldn't have a temporary input connection.
When the "extension cord is plugged in, you are creating a ground loop (through the earth).
And a path for a gradient pulse, created by a nearby lightning strike.
In your unique situation. The best option would be to disconnect the auxiliary ground rod, whenever the extension cord is plugged in.

 

[timselectric]

So, if the homeowner's old house has no GFCI can I assume that our city makes it safer by requiring our copper water supply pipe to be connected to the utility system ground?

Yes
The purpose of the grounding system is to provide a low impedance (resistance) path, back to the source. So that a fuse or breaker can open the circuit. And make it safe, before someone can get hurt.

 

[tinyt]

Yes
The purpose of the grounding system is to provide a low impedance (resistance) path, back to the source. So that a fuse or breaker can open the circuit. And make it safe, before someone can get hurt.

Thanks, now I understand why the inspector asked me to transfer from the ground rod to the copper water supply pipe.

 

[timselectric]

Thanks, now I understand why the inspector asked me to transfer from the ground rod to the copper water supply pipe.

It's hard to say without knowing what was in the mind of the inspector.
When you moved the service to the other side of the house. I assume that there was already a ground rod at the old location? And it was already connected to the water pipe, maybe?
Normally I would rebuild the grounding system, in this situation. But that choice might have been the easiest option.

 

[tinyt]

It's hard to say without knowing what was in the mind of the inspector.
When you moved the service to the other side of the house. I assume that there was already a ground rod at the old location? And it was already connected to the water pipe, maybe?
Normally I would rebuild the grounding system, in this situation. But that choice might have been the easiest option.

The old location was the back wall of the house and the ground wire is connected to the water copper pipe, I did not see any ground rod.

The new location is a wall of the garage. I bought a copper ground rod drove it to the ground below the new panel and connected the new panel ground to the rod with brass clamp. Grounding was the only issue he asked me to correct, I connected it to the same place as the old water pipe connection. I did not pull the rod anymore and left it unconnected.

 

[timselectric]

The old location was the back wall of the house and the ground wire is connected to the water copper pipe, I did not see any ground rod.

The new location is a wall of the garage. I bought a copper ground rod drove it to the ground below the new panel and connected the new panel ground to the rod with brass clamp. Grounding was the only issue he asked me to correct, I connected it to the same place as the old water pipe connection. I did not pull the rod anymore and left it unconnected.

There should be a connection to the earth.
If this omitted all connections, I might be concerned.
But if your water service is a metal pipe. I guess that would be good enough. That's all that we used to do (50 years ago). Now both are required, because of plastic water service pipes.

 

[Madcodger]

As a permanent installation (not mobile or portable), it really shouldn't have a temporary input connection.
When the "extension cord is plugged in, you are creating a ground loop (through the earth).
And a path for a gradient pulse, created by a nearby lightning strike.
In your unique situation. The best option would be to disconnect the auxiliary ground rod, whenever the extension cord is plugged in.

Thanks, Tim. And thanks to the OP as well, because this thread has been very helpful in allowing me to better understand grounding. I really only need the temporary AC input in winter, when our days get very short. Given that this is Maine, I've never seen a lightning strike in winter, so I think I'm probably pretty safe even if I forget to unplug it at both ends.