ground rod not needed at pool sub panel ?

[Fred B]

A long time ago it was allowed to have a subpanel in another space like a remote not connected garage to be simply run with a 4 conductor and no extra grounding as it was consider grounded via the 4th. Then it was one rod and now 2 rods.
Agreed the definition of a "structure" is really loose and open for a wide range of opinioned views, with that definition as is a pedestal (unless it is mfg. as a contiguous part of a panel, thus "equipment", and I know of none specifically) it is a structure as loosely defined. And thus required a GES.

 

[Dennis Alwon]

So a "pool panel" is actually a subpanel with branch circuits? OK.

yes, often a pool panel is mounted on a post, in the yard near a pool

 

[winnie]

I get the concept that 'equipment' doesn't require a grounding electrode system, but only because that 'equipment' has to serve power to something else, and that something else will be a structure which will requite a GES.

In this way, if you have say a building with pad mounted outdoor service equipment you don't end up with a requirement for multiple GESs.

In the case of a 'pool panel' mounted on a post, it seems to me that the whole thing (panel, post, conductors) qualifies as equipment, and thus would not need its own GES.

But doesn't the pool meet the definition of a structure, and require a GES? What about the pumps/filters/etc. being fed by the pool panel? It seems to me that even if the panel itself does not require a GES, there has to be one very close by.

-Jonathan

 

[kwired]

Agreed the definition of a "structure" is really loose and open for a wide range of opinioned views, with that definition as is a pedestal (unless it is mfg. as a contiguous part of a panel, thus "equipment", and I know of none specifically) it is a structure as loosely defined. And thus required a GES.

I agree definition of structure is wide open for interpretation. As mentioned earlier a naturally growing tree is about the only thing that maybe is clear enough to say is not a structure. A wood pole is something built or made, even if the process involved was pretty minimal. The fact one likely made a hole, placed it in there then filled around it is basically constructing something. It has different usage abilities when placed in the ground like that then when just lying on its side totally above grade.

 

[jaggedben]

does a ground rod really do what it suppose to
250.4(A) Grounded Systems.
(1) Electrical System Grounding. Electrical systems that are grounded shall be connected to earth in a manner that will limit the voltage imposed by lightning, line surges, or unintentional contact with higher-voltage lines and that will stabilize the voltage to earth during normal operation.
Informational Note No. 1: An important consideration for limiting the imposed voltage is the routing of bonding and grounding electrode conductors so that they are not any longer than necessary to complete the connection without disturbing the permanent parts of the installation and so that unnecessary bends and loops are avoided.

I can see for high voltage system but for resi I don't see how it can do anything. Earth reistance is two high for voltage sources around a residential even most Commerical for ground rods to do anything.

Line surges, helps but how much?

lighting, I saw mikes video on this, Seems like with system now all pex isolation from earth would be better so with a voltage gradient from lighting it would have no need to go through you home, if you had no point of contact with earth, such as no slap.
I see why you only want one point of contact with earth if you have a GE, But with everything isolated now days I don't see why a GE

I probably watched a video and just forgot, but those little rods just seem useless.

These are good questions and some good points. My sense is that individual electrodes do very little for high voltage contact and line surges, although in aggregate all the electrodes connected in a neighborhood make a difference. It's less clear how much an individual electrode helps with lightning, and probably depends more on the details of the installation, as well as luck. Do we really need electrodes at a pool panel attached to a post in the ground, in order to help with most of these things? I rather doubt it.

 

[kwired]

Do we really need electrodes at a pool panel attached to a post in the ground, in order to help with most of these things? I rather doubt it.

Though I believe the code does intend there to be an electrode in this example, I do agree that it likely has little impact with a rather direct lightning strike. It is one more point in the neighborhood network of electrodes though which is what having multiple electrodes over a system is about.

 

[petersonra]

How many of those electrodes are connected together though? How do they help anything if they are on different transformers.

And if they are on the same transformer, how does that make anything better?

 

[jaggedben]

Also it seems to me that if a pool panel is close to a swimming pool that is poured in the ground and complies with 680.26(B)(1) and (6) then rods for the panel will be totally superfluous. Even though that section does not talking about grounding, the copper grid or structural steel will likely act as a ufer.

 

[jaggedben]

How many of those electrodes are connected together though? How do they help anything if they are on different transformers.

And if they are on the same transformer, how does that make anything better?

Generally from what I see the bare grounded conductor on the utility poles connects all the transformer secondary (and primary,
in some places) grounded conductors together throughout the entire neighborhood. Which, by extension, connect all the service electrodes in the neighborhood to each other via the service neutrals.

 

[kwired]

How many of those electrodes are connected together though? How do they help anything if they are on different transformers.

And if they are on the same transformer, how does that make anything better?

usually all of them via the grounded/grounding conductors throughout the system that are all normally supposed to be bonded together?

They don't make a zero resistance connection to earth as single electrodes but over the entire network they are rather effective at making the grounded conductor at/near same potential as earth.

 

[LarryFine]

Also it seems to me that if a pool panel is close to a swimming pool that is poured in the ground and complies with 680.26(B)(1) and (6) then rods for the panel will be totally superfluous. Even though that section does not talking about grounding, the copper grid or structural steel will likely act as a ufer.

Agreed, although I don't think it would qualify.

 

[Rick 0920]

I don't understand the "sub-panel" being the defining point of requiring a ground rod. If I had a 200 A main breaker on the outside of a dwelling and a sub-panel in the garage where all of the branch circuits originated from, are you saying that I need another ground rod drilled through the slab in the garage to give this sub-panel it's own electrode? Wouldn't the pool panel that is being fed from the sub panel in the garage be the same circumstance? IMO, the main thing that a ground rod does in dwellings is give the POCO a "warm fuzzy" in case they lose their grounded conductor.

 

[LarryFine]

. . . I need another ground rod drilled through the slab in the garage to give this sub-panel it's own electrode?

No, because it's within the same structure.

Wouldn't the pool panel that is being fed from the sub panel in the garage be the same circumstance?

No, because it's not within the same structure.


It's the combination that triggers the requirement.

 

[kwired]

MO, the main thing that a ground rod does in dwellings is give the POCO a "warm fuzzy" in case they lose their grounded conductor.

A rod rarely does that though, too high of resistance to replace the current carrying ability of the grounded conductor.

Lost grounded conductor with medium voltages but still depending on a rod to complete the circuit is a different story, questionable situation yes but may actually function well enough to appear to be having no problems.