Two Groud Rods

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MarkRE

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I was recently told by an electrical inspector I needed to either test my ground rod impedance or drive a second ground rod. However this installation already has a ground rod AND a copper water main for electrodes. Isn't the "second ground rod" rule already satisfied?
 
The copper water pipe electrode is required to be supplemented by one additional electrode. As Bob and Derek stated the single rod needs to be proven that it has a resistance of 25 ohms or less to be considered an electrode. Or install two rods which is considered an electrode without the 25 ohm restriction.
 
The 2nd rod probably wont exist either as far as passing the ohms reading but you'd still be done regardless. :)

JAP>
 
MarkRE said:
I was recently told by an electrical inspector I needed to either test my ground rod impedance or drive a second ground rod. However this installation already has a ground rod AND a copper water main for electrodes. Isn't the "second ground rod" rule already satisfied?
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Take a look at 250.53(A)(2). The water pipe is not permitted to be the required supplemental electrode.
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: ...
Click to expand...
The exception to this section permits you to prove that the the single rod has a resistance of 25 ohms or less and not install the supplemental electrode.

While the wording and code sections has changed over the code cycles, this has really been the same rule for a long time.
 
To me, proving a ground rod has 25 ohms or less to ground is much like telling someone your in a good mood.
I might be at this particular moment, but, that's subject to change depending on circumstance.


JAP>
 
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