Grounding for panelboard in detached garage


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Old 06-08-20, 09:02 AM
W
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Grounding for panelboard in detached garage

Hello. Earlier in the year I had posted some questions regarding running electrical power to a detached garage that I am having built. Due to the COVID-19 situation, the contractor doing the work has been delayed and the construction has yet to begin.

I am going to be running a 60-amp circuit from my residence out to the garage. Several Posters on this site gave me valuable information and I appreciate it very much.

I have a question regarding the grounding of the panelboard in the garage and using the method of bonding it to reinforcement rod (re-rod) encased in the footing of the garage as opposed to sinking two ground rods six feet apart in the soil outside of the garage. Is grounding to re-rod considered to be a preferred/better method for the garage's electrical system? I know both methods are acceptable, but what is the opinion of individuals on this forum? Thank you!
 
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Old 06-08-20, 10:01 AM
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It is called a Ufer ground. I don't either one is better than the other. I think in some place new construction is supposed to use the Ufer method.
 
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Old 06-08-20, 10:04 AM
Z
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Generally, a Ufer (concrete encased) ground provides a better ground than one or two 8' copper ground rods. Just the math of 20'+ of the steel well-encased in concrete, gives a more reliable ground than a driven rod.

But lik you said, either are acceptable.
 
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Old 06-08-20, 10:05 AM
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Thank you Joed. I appreciate your comment.
 
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Old 06-08-20, 10:09 AM
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Hello Zorfdt. Thank you for your reply to my question. I am thinking that I will most likely go with the Ufer method.
 
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Old 06-10-20, 05:23 AM
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For buildings built after a certain date (which I don't recall or have in front of me) if the building possesses buried metal reinforced concrete then a section of that metal must be incorporated into the building electrical ground (grounding electrode system) as a "concrete encased electrode" aka Ufer electrode.

For older buildings, if such reinforcing metal has an exposed end and is not known to run for fewer than 20 feet including multiple pieces joined with tie wires within the buried concrete, then one such must be included in the GES as an electrode.
 

Last edited by AllanJ; 06-10-20 at 05:39 AM.
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Old 06-10-20, 06:50 PM
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UFER ground is best

It’s not clear where in the US where you are from, but the NEC has required since 2017 that the concrete encased ground electrodes be used instead of the 2 driven rods - they are still acceptable but only if there are no concrete encased electrodes in the foundation.
even if you were in a jurisdiction which used an older code I would think you would want to utilize the UFER ground as it has proven to be much more effective.
 
 

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