Grounding rod for town homes? Separate rods or bond them?

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Cartoon1

Cartoon1

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Electrical Engineer
I have a 4 townhomes type building, they are being considered as a separate property (where two are in the middle of the 4). Each townhome is getting its own meter and enclosed breaker outside. Two separate 400A with their own meter from each side of the building, So.... two meters feed from each side of building coming from Poco transformer (unknown location for now). My question is , do i provide a grounding rod and share it at each side or provide a separate rod for every service? See figure. I didn't see this particular case mentioned in the NEC so I'm not familiar with this type of situation, any help would be great!!

Thank you
 

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You may want to check with the AHJ, but they probably should let you treat the situation as multiple buildings, in which case you could do separate grounding electrode systems for each side. The relevant parts of Article 250 Part III refer to the 'building or structure' and article 100 allow would allow townhomes divided by firewalls to be considered separate buildings.

You don't need to be driving rods if there is a ufer to connect to, at least not per the NEC. Also is the water service metal, and how many are there?

It's unclear if you have two services or four. I'm guessing two. Regardless, each pair of meters should share a grounding electrode system (that's how I'd do it), if the AHJ doesn't require them all to share one.
 
jaggedben said:
You may want to check with the AHJ, but they probably should let you treat the situation as multiple buildings, in which case you could do separate grounding electrode systems for each side. The relevant parts of Article 250 Part III refer to the 'building or structure' and article 100 allow would allow townhomes divided by firewalls to be considered separate buildings.

You don't need to be driving rods if there is a ufer to connect to, at least not per the NEC. Also is the water service metal, and how many are there?

It's unclear if you have two services or four. I'm guessing two. Regardless, each pair of meters should share a grounding electrode system (that's how I'd do it), if the AHJ doesn't require them all to share one.
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Well technically there will be a run from the utility transformer to each meter (so 4 i guess). But i had a similiar thought as you, where i would share the ground rod for the two that are next to each other. The utility standards dosent cover this situation and i have not heard back from them.
 
Cartoon1 said:
Well technically there will be a run from the utility transformer to each meter (so 4 i guess). But i had a similiar thought as you, where i would share the ground rod for the two that are next to each other. The utility standards dosent cover this situation and i have not heard back from them.
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Going to have 4 seperate water lines also.
 
Depending on how the AHJ wants to intepret the situation, I believe they could require the middle two units to have disconnects and grounding electrodes at each middle unit. It all depends on whether they treat each unit as it's own 'building' or let you divide it up how you want. You probably just need to confirm with them.

Utility requirements could be totally different from the NEC. The utilities I work with have zero grounding requirements (other than green tag from building dept) but I've heard on this forum that other utilities require rods and such.
 
Well if you happen to be Duke Energy, hope this helps

Requirements for Electric Service and Meter Installations Florida Service Area|Revised April 1, 2020

A PDF
158 pages and plenty of pictures, and the in almost every picture some reference like:

1. METER ENCLOSURE SHALL BE BONDED TO GROUND AS REQUIRED BY THE N.E.C. OR AUTHORITY HAVING JURISDICTION.

Granted it doesn't show anything like your describing...
I've said this before here, the POCO doesn't like to Pay for the Cost (in power) of the lateral service from the Trannie to meter.

Here's another broader link for Duke Energy for Florida
https://www.duke-energy.com/partner-with-us/builders-developers-and-contractors/construction-toolbox
Construction Toolbox

You don't need to register, go to the bottom, more PDF's links
 
cadpoint said:
Well if you happen to be Duke Energy, hope this helps

Requirements for Electric Service and Meter Installations Florida Service Area|Revised April 1, 2020

A PDF
158 pages and plenty of pictures, and the in almost every picture some reference like:

1. METER ENCLOSURE SHALL BE BONDED TO GROUND AS REQUIRED BY THE N.E.C. OR AUTHORITY HAVING JURISDICTION.

Granted it doesn't show anything like your describing...
I've said this before here, the POCO doesn't like to Pay for the Cost (in power) of the lateral service from the Trannie to meter.

Here's another broader link for Duke Energy for Florida
https://www.duke-energy.com/partner-with-us/builders-developers-and-contractors/construction-toolbox
Construction Toolbox

You don't need to register, go to the bottom, more PDF's links
Click to expand...
Thanks!! different utility for me. But this is helpful!!
 
If you did share the grounding rod.... what about the possibility of a ground fault in one property being imported into the other? (Especially, if/when the connection to the rod becomes compromised at some point in the future)

Here on our side of the pond (UK) sharing a ground rod would be a big no-no. (That doesn't mean to say that each property, each with its own ground rod, couldn't have the grounds commoned)
 
Is it feasible to provide a separate ground rod for each service and not bond them? So 4 services and 4 ground rods. Even though some of the ground rods will be close to the other service ground rods (treat each townhome as a separate service technically)? My issues is that, do the the ground rods next to each other from the separate service need to be bonded and if so.... why not bond all grounding rods together?? kind of a dilemma
 
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LarryFine said:
One electrode (system) can serve more than one service, and a structure's electrodes should be tied together.
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So if I understand this correctly. If i have two services sharing a ground rod on one side of the building and i have another two services sharing a ground rod on the other side of the building (Total 4 service since this building is split into 4 separate occupants) that i should bond the ground rods between the two even if the ground rods location like 80feet from each other?
 
Cartoon1 said:
So if I understand this correctly. If i have two services sharing a ground rod on one side of the building and i have another two services sharing a ground rod on the other side of the building (Total 4 service since this building is split into 4 separate occupants) that i should bond the ground rods between the two even if the ground rods location like 80feet from each other?
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If it's a single structure, yes. If it's two or four separate structures (fire walls count as separating structures), then not necessary.
 
LarryFine said:
If it's a single structure, yes. If it's two or four separate structures (fire walls count as separating structures), then not necessary.
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In this particular case it is going to be considered as a separate structure (so 4 seperate structures). But if the grounding rods are next to each other from service to service, wouldnt that cause a potential diffrence?? that is my worry, if it is okay to not bond them to each other even though they will be next to each other as two of the services will be right by each other and another two services will be by each other on the other side.
 
I would definitely use the same electrodes for each pair of services.

Remember, rods never need larger than #6 cu, nor Ufers larger than #4 cu.
 
One ground rod isn't sufficient to meet NEC requirements for a service. However, two ground rods is sufficient and can be used for as many services as you like.

You also still have to bond any metal water service pipe.
 
jaggedben said:
One ground rod isn't sufficient to meet NEC requirements for a service. However, two ground rods is sufficient and can be used for as many services as you like.

You also still have to bond any metal water service pipe.
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Yes, I plan on running the separate services to the same ground rods. I plan to provide a minimum 2 grounds rod with a minimum of 6 feet from each other bonded together. And also bonding to metal water service. Thank you
 
Each townhouse could be viewed as a separate building, are you using 2 position meter packs for each end? unless you have a UFER present each meter pack would need a set of ground rods and each metallic water pipe bonded for the town homes that meter pack serves.
 
mbednarik said:
Each townhouse could be viewed as a separate building, are you using 2 position meter packs for each end? unless you have a UFER present each meter pack would need a set of ground rods and each metallic water pipe bonded for the town homes that meter pack serves.
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No. separate meters for each townhouse, all lined by each other for a total of 4. That would be connected to two ground rods bonded together or at least that is what i plan on doing.
 
The OP seems to be referring to the same project in this post: https://forums.mikeholt.com/threads/different-services-for-a-town-home-type-build-out.2571727/page-2
I made a number of post there and was roundly ignored. But it would seem that he has now realized that he has a true townhouse and not a condo. and he needs to have a service to/on each unit-not a feeder from a central meter bank. So now this post is asking about GES. I'll say it again-these are separate buildings in the eyes of all the codes just like a single family dwelling. You can't run GES bonding jumpers to, through or on another units property. Just set up a GES for each unit. In addition, the diagram shows services located on each end on the wall of the end units- he can't have another units service there as that wall legally belongs to that unit.
 
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