Grounding Electrodes

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ccarr7

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Guys,

I normally look to have all ground electrode conductors installed to the first point of disconnect, bond the neutral to ground there, and then use the equipment grounding requirements on in through the system on the load side of the disconnect.

However, I occassionally come across cases where it is very difficult to get electrode conductors such as water pipe and building steel out to an outside main disconnect.

Is there any issue with installing a ground electrode from a ground rod to the outside disconnect, while installing additional ground electrodes such as from water pipe and building steel to the main distribution panel? In this scenario, I believe it would still be best to bond the neutral to ground at the outside disconnect. Do you guys agree and if so, can the service entrance pipe(s) be relied upon as an equipment ground in this case?

Thanks,
Creig
 
All the electrodes need to be connected at the service. This means before at or before the service disco. 250.64
 
OK...Thanks.

I have a case where the external disconnect is approximately 50' away from the service entrance into the building and it's going to be extremely difficult to get a GEC from a water pipe or building steel out to it due to a 4' high concrete filled dock between the disconnect and the service entrance (this is a very unusual case).

Is it acceptable to only consider a ground rod or two with a GEC to the outside disconnect as suffice?
 
ccarr7 said:
OK...Thanks.

I have a case where the external disconnect is approximately 50' away from the service entrance into the building and it's going to be extremely difficult to get a GEC from a water pipe or building steel out to it due to a 4' high concrete filled dock between the disconnect and the service entrance (this is a very unusual case).

Is it acceptable to only consider a ground rod or two with a GEC to the outside disconnect as suffice?
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You must use all available electrodes as well as the ground rod or other made electrode accepted by art. 250. All metal piping must also be bonded.
 
If the service is 50 feet away from the building is there a disconnect located on the building in accordance with 225.31?

Chris
 
Chris,

Yes, there is a disconnect enclosure installed on the building. The issue I'm having is with installing the ground electrode conductors from the water pipe and from building steel to it. I'd rather not install additional conduits along the wall of the building for them if I can find another alternative. One thing I was going to look into was possibly mounting a ground bus in the electric room or perhaps even in the panel, pulling the two GEC's to it and then pull a conductor from it through one of the two service entrance pipes to the external main disconnect. I have to do some research in NEC though to see if this is acceptable. If you have any thoughts on that, I'd appreciate it.

Thanks,
Creig
 
Can you bury the conductor under the dirt a few inches so you won't have to pipe it. I don't believe there is a burial depth requirement for a GEC.
 
Dennis,

No, unfortunately there is an elevated walkway about 4' deep with concrete between the tenant space and the disconnect...the whole stretch is also asphalt.

Thanks,
Creig
 
ccarr7

You only need one ground electrode conductor. You may bond the other electrodes to each other or to the main GEC to form your grounding electrode system.

shortcircuit2
 
Assuming I bond the water pipe and building steel together, can the one GEC be pulled back through one of my service entrance pipes in order to be landed at the first point of disconnect (external main breaker mounted on the side of the building)?
 
ccarr7 said:
Assuming I bond the water pipe and building steel together, can the one GEC be pulled back through one of my service entrance pipes in order to be landed at the first point of disconnect (external main breaker mounted on the side of the building)?
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Yes, provided that you comply with 250.64, specifically (E).

Chris
 
You can install a ground rod as the sole grounding electrode next to the outside disconnect. You can then bond the structural steel and water pipe to the equipment ground. NEC 250.32(B) state's:

The equipment grounding conductor shall be used for grounding or bonding of equipment, structures, or frames required to be grounded or bonded.
 
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