gserve
Senior Member
- Location
- New Hampshire
Is a supplemental electrode required when you establish a GES at another building like a detached garage? Does it need 2 ground rods like at a house if the 25 ohms is not met? Thanks
supplemental electrode
- Thread starter gserve
- Start date
- Status
- Location
- Lockport, IL
- Occupation
- Retired Electrical Engineer
Re: supplemental electrode
A garage has to have a "Grounding Electrode System," in the same context as the house. You can use building steel or a concrete-encased electrode, if you wish. But I doubt that a garage is going to have either of these. It is also unlikely that a water pipe will be available for use as a grounding electrode. So you are most likely stuck with using a ground rod.
My answer is that you would need to "augment" (that's the right word, not "supplement") the rod with a second rod, if you can't prove that you meet the 25 ohms.
A garage has to have a "Grounding Electrode System," in the same context as the house. You can use building steel or a concrete-encased electrode, if you wish. But I doubt that a garage is going to have either of these. It is also unlikely that a water pipe will be available for use as a grounding electrode. So you are most likely stuck with using a ground rod.
My answer is that you would need to "augment" (that's the right word, not "supplement") the rod with a second rod, if you can't prove that you meet the 25 ohms.
Re: supplemental electrode
I tried to convince my inspector that the house rods were my second "augmented" rod, and that it is bonded to the detached building's rod via the equipment grounding wire in the feeder. He wouldn't buy that, but I don't know why. I don't see anything in the code that would prohibit this as long as the EGC was #8 or larger. Code mandates a minimum rod spacing, but no maximum.
Also, you don't need a ground electrode system at the garage if it is served by only a branch circuit or multiwire branch circuit.
[ October 03, 2005, 10:14 PM: Message edited by: suemarkp ]
I tried to convince my inspector that the house rods were my second "augmented" rod, and that it is bonded to the detached building's rod via the equipment grounding wire in the feeder. He wouldn't buy that, but I don't know why. I don't see anything in the code that would prohibit this as long as the EGC was #8 or larger. Code mandates a minimum rod spacing, but no maximum.
Also, you don't need a ground electrode system at the garage if it is served by only a branch circuit or multiwire branch circuit.
[ October 03, 2005, 10:14 PM: Message edited by: suemarkp ]
jwelectric
Senior Member
- Location
- North Carolina
- Location
- Lockport, IL
- Occupation
- Retired Electrical Engineer
Re: supplemental electrode
EGCs and GECs are sized by different rules, and they serve different purposes. This may not be practical, but just for the sake of discussion, how about running a bonding wire from the garage ground rod to the house ground rod. That would satisfy the rule, as I read the rule.
EGCs and GECs are sized by different rules, and they serve different purposes. This may not be practical, but just for the sake of discussion, how about running a bonding wire from the garage ground rod to the house ground rod. That would satisfy the rule, as I read the rule.
Re: supplemental electrode
If a conductor is sized to meet the minimum of either, then can't the same conductor be both a EGC and a GEC? (I'm not sure if I am agreeing or disagreeing with Charlie B
).
More than once I see the pharse "Two or more grounding electrodes that are effectively bonded together shall be considered a single grounding electrode system."
I also see the requirements for bonding jumpers in 230.53 (C) (2002 NEC). I don't see any reason the feeder EGC could meet all these requirements. I notice the requirement for "Continuous" in 250.64(C) is left out of 230.53(C), which also makes me think the electrode at the house could be the "argumenting" electrode.
Steve
If a conductor is sized to meet the minimum of either, then can't the same conductor be both a EGC and a GEC? (I'm not sure if I am agreeing or disagreeing with Charlie B
).More than once I see the pharse "Two or more grounding electrodes that are effectively bonded together shall be considered a single grounding electrode system."
I also see the requirements for bonding jumpers in 230.53 (C) (2002 NEC). I don't see any reason the feeder EGC could meet all these requirements. I notice the requirement for "Continuous" in 250.64(C) is left out of 230.53(C), which also makes me think the electrode at the house could be the "argumenting" electrode.
Steve
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