Sharing Ground Rods

[Jaysee62]

Question on sharing ground rods: I have an outdoor sub panel, not mounted on the house ( it is mounted on metal structure with the poles in concrete) to power my pool equipment. Taking the " rule out any questions if a separate ground rod is required) I will use two ground rods ( i don't have the equipment to test a single ground rod) for the panel ground.
Here is the question: Can I use/share the ground rod installed below my main service panel to the house as the second ground rod?

Thanks for responses.

 

[Dennis Alwon]

Question on sharing ground rods: I have an outdoor sub panel, not mounted on the house ( it is mounted on metal structure with the poles in concrete) to power my pool equipment. Taking the " rule out any questions if a separate ground rod is required) I will use two ground rods ( i don't have the equipment to test a single ground rod) for the panel ground.
Here is the question: Can I use/share the ground rod installed below my main service panel to the house as the second ground rod?

Thanks for responses.

The only issue would be the distance. The nec doesn't give us any real numbers to use but the ground electrode conductor should be as short as possible. If you had 2 rods at the house you could use those rods as your grounding electrode conductor for the pool pump.

Imo, you can use the equipment grounding conductor to the pool panel as the grounding electrode conductor if it is size large enough for the rods. Again the shorter the better.

250.118 (B) Not Permitted.
The following shall not be used as equipment grounding conductors.

• (1)
  Grounding electrode conductors
  Exception:
  A wire-type equipment grounding conductor installed in compliance with 250.6(A) and the applicable requirements for both the equipment grounding conductor and the grounding electrode conductor in Parts II, III, and VI of this article shall be permitted to serve as both an equipment grounding conductor and a grounding electrode conductor.

 

[LarryFine]

Can I use/share the ground rod installed below my main service panel to the house as the second ground rod?

Yes, both panels may share the same electrodes; sometimes, it's preferable.

 

[david]

Imo, you can use the equipment grounding conductor to the pool panel as the grounding electrode conductor if it is size large enough for the rods. Again the shorter the better.

250.121(A) 2020 NEC

Yes, both panels may share the same electrodes; sometimes, it's preferable.

So your saying driving two ground rods out at the pool panel and connecting them to the equipment ground buss of a four wire feed to the pool panel would create objectionable currents

Just for clarification.

 

[david]

Dennis

250.121(A) 2020 NEC



So your saying driving two ground rods out at the pool panel and connecting them to the equipment ground buss of a four wire feed to the pool panel would create objectionable currents

Just for clarification.

 

[LarryFine]

So your saying driving two ground rods out at the pool panel and connecting them to the equipment ground buss of a four wire feed to the pool panel would create objectionable currents

No, because the earth between the separate electrodes is not considered conductive enough to be considered to be a parallel pathway. That's also why a neutral can be earthed in more than one place.

 

[Dennis Alwon]

I never mentioned objectional currents. I said 2 rods at the house and IF your equipment grounding conductor is as large as needed to satisfy T250.66 or, in this case, 250.104 then it would be compliant. No Obj. Current

 

[david]

I never mentioned objectional currents. I said 2 rods at the house and IF your equipment grounding conductor is as large as needed to satisfy T250.66 or, in this case, 250.104 then it would be compliant. No Obj. Current

I'm sorry I went to 250.6 (A)
Is about removing multiple grounding points when objectionable currents are created


You posted the exception to 250.121(A) that sends you to 250.6 (A)
Sorry I must have miss read it

 

[david]

No, because the earth between the separate electrodes is not considered conductive enough to be considered to be a parallel pathway. That's also why a neutral can be earthed in more than one place.

Actually it/I somehow messed up and replied to you when I met to reply to Dennis

But now that you mentioned it the OP isn't talking about using the earth he said drive one rod out at the pool equipment and run a grounding electrode bond to the house grounding electrode system as his second ground rod
I probably wouldn't do that for an in ground ipool n case the house neutral got compromised. The pool grounding would have a pretty big foot print into the earth some of the currents may use that foot print into the earth to stray back to the utility transformer.


All the bonding at the pool should prevent any concerns. I just would not use that option.


The motor circuit equipment ground already creates that bond to the system neutral. It's just me but I wouldn't do it even though the NEC allows it

 

[david]

Imo, you can use the equipment grounding conductor to the pool panel as the grounding electrode conductor if it is size large enough for the rods. Again the shorter the better.

250.121(A)
An equipment grounding conductor shall not be used as a grounding electrode conductor


Exception

A wire type equipment grounding conductor installed in compliance with 250.6(A)

250.6 objectionable currents

When you said an equipment ground if large enough could be used as the grounding electrode conductor. I took it that you were referring to objectionable currents
That's why I ask for clarification

 

[david]

I didn't m

I never mentioned objectional currents. I said 2 rods at the house and IF your equipment grounding conductor is as large as needed to satisfy T250.66 or, in this case, 250.104 then it would be compliant.

I never mentioned objectional currents. I said 2 rods at the house and IF your equipment grounding conductor is as large as needed to satisfy T250.66 or, in this case, 250.104 then it would be compliant. No Obj. Current

I didn't mean to offend you.
I was only asking for clarification

You're participating on this site helps make it as good as it is

 

[Dennis Alwon]

I didn't m



I didn't mean to offend you.
I was only asking for clarification

You're participating on this site helps make it as good as it is

Thank you but I wasn't offended. lol

 

[Dennis Alwon]

250.121(A)
An equipment grounding conductor shall not be used as a grounding electrode conductor


Exception

A wire type equipment grounding conductor installed in compliance with 250.6(A)

250.6 objectionable currents

When you said an equipment ground if large enough could be used as the grounding electrode conductor. I took it that you were referring to objectionable currents
That's why I ask for clarification

Basically if the equipment ground for the feeder was only #10 you would have to increase it to #6 in order to be used as the grounding electrode conductor also.

 

[david]

Basically if the equipment ground for the feeder was only #10 you would have to increase it to #6 in order to be used as the grounding electrode conductor also.

In the OP case this is a new install. Do you think 250.6(A) could stand alone

Would you not have to be responding to currents present before taking any action as in 250.6 (B)

I'm not sure of the results of any recent discussion here on 250.6.

If I'm remembering correctly a few years back, l think it was Don who said you would have to have Objectional currents first before any action could be taken to remove them.

If that is true you couldn't at the starting gate just supply the panel with a wire that could serve as both with the intention of not having a grounding electrode at that location

If you already clarified you're position on that when you stated "Imo " is fine

 

[jaggedben]

I think this thread has gotten started on the wrong track.

Is the subpanel mounted on a separate structure? If so see 250.32. A separate structure supplied by a feeder needs two rods (or equivalent). It cannot share electrodes with the house.

If you can say that the subpanel is not at a separate structure then it needs no electrodes at all.

 

[Dennis Alwon]

I think this thread has gotten started on the wrong track.

Is the subpanel mounted on a separate structure? If so see 250.32. A separate structure supplied by a feeder needs two rods (or equivalent). It cannot share electrodes with the house.

If you can say that the subpanel is not at a separate structure then it needs no electrodes at all.

Can you show me where it states that you cannot share the electrodes

 

[david]

I think this thread has gotten started on the wrong track.

Is the subpanel mounted on a separate structure? If so see 250.32. A separate structure supplied by a feeder needs two rods (or equivalent). It cannot share electrodes with the house.

If you can say that the subpanel is not at a separate structure then it needs no electrodes at all.

You as well help make this site worth visiting. 250.32 for years has not been interpreted that way. There are a lot of industrial sites that have a 3/0 copper run through out and every building on site is cad welded to that grounding electrode system


Also every cell phone tower site I ever been o

 

[david]

You as well help make this site worth visiting. 250.32 for years has not been interpreted that way. There are a lot of industrial sites that have a 3/0 copper run through out and every building on site is cad welded to that grounding electrode system


Also every cell phone tower site I ever been on does the same thing using 10 ft 3/4 ground rods every 10 ft apart

 

[jaggedben]

Can you show me where it states that you cannot share the electrodes

250.32. The separate structure needs its own GES.

 

[david]

Question on sharing ground rods: I have an outdoor sub panel, not mounted on the house ( it is mounted on metal structure with the poles in concrete) to power my pool equipment.

Here the utilities all started requiring the same kind of metal pole support as you described for pedestal services.
Electricians started following that design for all there pedestals.

I think the metal pole support structure takes 250.6 off the table anyhow Imo
It's my understanding you're aloud to do what you asked about doing. But I also said from my point of view I don't recommend you doing it