# of ground rods required at a residential detached storage building?

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Ravenvalor

Ravenvalor

Senior Member
Location
Triad region of NC
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Electrician
Hello,

Can someone please refer me to the code that states how many ground rods are required at a residential detached storage building?

Thanks,
 
If you had another electrode like a CEE then no rods are needed. Otherwise if rods are being used then you would need two. There is an exception to use only one if you can prove 25 ohms or less on the one rod.
 
Thanks for all of the good replies. The local inspector only requires one at generators and panels for swimming pool equipment. I was hoping there was something in the NEC for storage buildings. I will call him about storage buildings tomorrow. If he can reference a code that only requires one I will post it tomorrow.

I appreciate the help.
 
Any separate structure or building supplied with a feeder is required to have it's own grounding electrode system.

250.32(A)
 
Ravenvalor said:
Thanks for all of the good replies. The local inspector only requires one [rod] at generators and panels for swimming pool equipment.
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I confess to being a bit weak on all the Art. 680 requirements...could someone provide the code section requiring grounding electrodes for pool panels? [I do understand the requirement if said panel is in a separate structure]...I'm supposing this refers to the pool equipment being supplied from a panel other than at the service.
 
dana1028 said:
I confess to being a bit weak on all the Art. 680 requirements...could someone provide the code section requiring grounding electrodes for pool panels? [I do understand the requirement if said panel is in a separate structure]...
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If the 'pool panel' is not in, or on the building with the service it will need a grounding electrode system.

Even if you sink just one 4x4 into the ground and mount the panel to it you have made a structure that is supplied by a feeder.
 
Ravenvalor said:
If he can reference a code that only requires one I will post it tomorrow.
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Of course he can, it is 250.56 but it is doubtfull that you would be able to meet the 25 ohms or less requirement.

In as much as the local inspector is allowing you to drive one rod for generator and pool GE's, he is using common sense but, unless he is requiring you to prove 25 ohms or less he is not inspecting for code compliance.

Roger
 
I would not apply the 'two rods' idea to a detached structure- after all, the rod is connected to the rod at the house (albeit indirectly via the green wire in the feeder).

Please note that I do not agree with the idea of treating a detached building as a separate service, not requiring that green wire with the feed, either. Keep neutrals and grounds separate- period.
 
roger said:
Yes it is and unless Reno has an inspector that is not inspecting to the letter of the code he will have to use two rods or show 25 ohms or less.

Roger
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Instead of us having to prove it is 25 ohms or less, why doesn't the inspector have to prove it's not.:D If you go to an Emissions testing center, they have to provide the test equipment.:thumbsup:
No offense to you inspectors on here.
 
Little Bill said:
Instead of us having to prove it is 25 ohms or less, why doesn't the inspector have to prove it's not.:D If you go to an Emissions testing center, they have to provide the test equipment.:thumbsup:
No offense to you inspectors on here.
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Biil, IMO, it's the same as commissioning an OR, you have to provide all the required test results or the inspector walks away and says to call him after you are ready. It would be great if an inspector showed up with a butt load of analyzers to prove the test criteria but it doesn't work that way.;)

This is the reason the majority of EC's just drive the second rod and go home.

Roger
 
roger said:
Biil, IMO, it's the same as commissioning an OR, you have to provide all the required test results or the inspector walks away and says to call him after you are ready. It would be great if an inspector showed up with a butt load of analyzers to prove the test criteria but it doesn't work that way.;)

This is the reason the majority of EC's just drive the second rod and go home.


Roger
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I know but I was just dreaming during my Sunday afternoon nap.:lol:
 
I would think you can count the second rod at the house as your supplemental electrode if you ran a #6 EGC in your feeder. All the code requires is that your second electrode be at least 6' away from the first -- there is no maximum distance (however, I think the intent is that it be near the structure). There is no prohibition on splicing bonding jumpers between rods, but that jumper must be #6 cu or larger. I don't believe a ground electrode bonding jumper is prohibited from serving another purpose (e.g. feeder bonding conductor).
 
Little Bill said:
Instead of us having to prove it is 25 ohms or less, why doesn't the inspector have to prove it's not.:D
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Because the code says that a single rod needs to be supplemented by an additional electrode. The exception allows one rod if it's 25 ohms or less. If you only install one rod as per the exception you would need to know that it was already 25 ohms or less.

250.53(A)(2) Supplemental Electrode Required. A single rod, pipe,
or plate electrode shall be supplemented by an additional
electrode of a type specified in 250.52(A)(2) through
(A)(8). The supplemental electrode shall be permitted to be
bonded to one of the following:
(1) Rod, pipe, or plate electrode
(2) Grounding electrode conductor
(3) Grounded service-entrance conductor
(4) Nonflexible grounded service raceway
(5) Any grounded service enclosure
Exception: If a single rod, pipe, or plate grounding electrode
has a resistance to earth of 25 ohms or less, the
supplemental electrode shall not be required.
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suemarkp said:
I would think you can count the second rod at the house as your supplemental electrode if you ran a #6 EGC in your feeder. All the code requires is that your second electrode be at least 6' away from the first -- there is no maximum distance (however, I think the intent is that it be near the structure). There is no prohibition on splicing bonding jumpers between rods, but that jumper must be #6 cu or larger. I don't believe a ground electrode bonding jumper is prohibited from serving another purpose (e.g. feeder bonding conductor).
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That would be nice if we could, but the wording in 250 says each structure shall have it's own grounding electrode system, See 250.50 the first sentence
 
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