Grounding question

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codequestion

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I have service disconnect on unistrut that has grounding electrode system. 20 feet away from the service disconnect I have an ATM on conceret pad with panel A with main breaker and feeder breaks feeding the ATM.

The service disconnect feeds Panel A. Do I need to have grounding electrodes at Panel A or I can just extend the ground from the service disconnect?

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You need a grounding electrode at each panel location that is detached from the other.

I believe you can extend the grounding electrode conductor from the service to the panel at the other structure. In fact, I believe you can size your feeder equipment grounding conductor appropriately and use it as the grounding electrode conductor.
 
Here is the section

250.121 Use of Equipment Grounding Conductors. 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) 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.
Click to expand...
 
Dennis Alwon said:
You need a grounding electrode at each panel location that is detached from the other.

I believe you can extend the grounding electrode conductor from the service to the panel at the other structure. In fact, I believe you can size your feeder equipment grounding conductor appropriately and use it as the grounding electrode conductor.
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So on load side of service disconnect from ground bar I can size equipment grounding conductor to Panel A per table 250.122 and I would not need grounding electrode at Panel A ATM? I can use the grounding electrode from service disconnect?

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codequestion said:
So on load side of service disconnect from ground bar I can size equipment grounding conductor to Panel A per table 250.122 and I would not need grounding electrode at Panel A ATM? I can use the grounding electrode from service disconnect?

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Click to expand...
The AHJ who interprets NEC 2014 is telling me that since service disconnect and its grounding electrode system is 20 feet from concrete pad ATM both service disconnect and ATM is essentially considered one building and so grounding electrode and bonding at the ATM is not required just equipment ground condctor from service disconnect to the ATM is ok. However, i dont see anywhere in code that says 20 feet is considered same building.

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codequestion said:
The AHJ who interprets NEC 2014 is telling me that since service disconnect and its grounding electrode system is 20 feet from concrete pad ATM both service disconnect and ATM is essentially considered one building and so grounding electrode and bonding at the ATM is not required just equipment ground condctor from service disconnect to the ATM is ok. However, i dont see anywhere in code that says 20 feet is considered same building.

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Click to expand...

You won't find it in the NEC because it isn't there. As Dennis mentioned, as long as your equipment grounding conductor meets the requirements in the exception to 250.121, it can be used as both and EGC and a GEC.

If there are qualifying grounding electrodes at the concrete ATM pad, that would change things IMO.
 
packersparky said:
You won't find it in the NEC because it isn't there. As Dennis mentioned, as long as your equipment grounding conductor meets the requirements in the exception to 250.121, it can be used as both and EGC and a GEC.

If there are qualifying grounding electrodes at the concrete ATM pad, that would change things IMO.
Click to expand...
Concrete encased electrode ATM concrete pad, ATM structural steel is there but not sure if structural steel is like building. But cannot those electrodes be bonded to service disconnect since it is 20 feet away.

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Last edited:
codequestion said:
Concrete encased electrode ATM concrete pad, ATM structural steel is there but not sure if structural steel is like building. But cannot those electrodes be bonded to service disconnect since it is 20 feet away.

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If there is a concrete encased electrode at the atm then you can use it. This was answered already so I am not sure why you are asking the same question.
 
Dennis Alwon said:
If there is a concrete encased electrode at the atm then you can use it. This was answered already so I am not sure why you are asking the same question.
Click to expand...
Post #6 said if there are qualifying electrods at the ATM that would change things. There is concrete encased qualifying electrode at ATM. I was wondering what would change.

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codequestion said:
I have service disconnect on unistrut that has grounding electrode system. 20 feet away from the service disconnect I have an ATM on conceret pad with panel A with main breaker and feeder breaks feeding the ATM.

The service disconnect feeds Panel A. Do I need to have grounding electrodes at Panel A or I can just extend the ground from the service disconnect?

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Click to expand...

Instead of extend like above ppst says I can also use nec 250.32 (A) in this case?

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codequestion said:
Post #6 said if there are qualifying electrods at the ATM that would change things. There is concrete encased qualifying electrode at ATM. I was wondering what would change.

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If there is a qualifying electrode at a structure then 250.50 says you must use it.
 
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