I just posted this question on Mike Holt's site but thought I would also post it here also.
We just installed a new 200 amp service for a single family dwelling. We connected the grounding electrode conductor to the underground water service (aprox. 30' of 1 1/4" copper) and to a concrete encased electrode. The concrete encased electrode consisted of two 20' sections of rebar tied to the bottom rebar in the footing. The total length of the concrete encased electrode exceeds 50' and was signed off by the inspector before the foundation was poured. Today we had the inspection on our service and the inspector said that unless we can prove that the concrete encased electrode has a resistance of 25 ohms or less we must install a ground rod to supplement it. 250.56 requires the rod, pipe and plate electrodes must have a resistance of 25 ohms or less but does not say anything about concrete encased electrodes. I have been in business in Northern California for almost 20 years and have never had an inspector question the resistance concrete encased electrode but am curious as to what inspectors require in other areas so any feed back would be appreciated. The inspector also we could make the test with a ohm meter which is definitely not the proper piece of equipment to use to test grounding electrodes.
Joe, I think you're being too easy on this one. Local rule or not, the guy is wrong!!!! The Ufer is one of the most consistent grounds. Remember the IEEE study, only the ring was better, and that not all the time.
Re: Concrete Encased Electrode?#81555 08/28/0206:21 AM08/28/0206:21 AM
1. Metal UG water pipe, Metal Bldg Frame, Concrete encased electrodes, and ground rings are not "Made Electrodes".
2. Only if one of the electrodes in #1 isn't available is a made electrode to be used. Exception: a sole Metal UG water pipe must be supplemented with an additional electrode (either mentioned in #1 or a made electrode).
3. If solely, a single made electrode is used must you meet the 25 ohm rule.
4. If a single electrode doesn't meet the 25 ohm rule it can be augmented by one of the electrodes mentioned in #1 or an additional made electrode placed at least 6 ft from the first made electrode.
5. If the electrodes mentioned in #1 are on the premise along with a made electrode and they are not bonded, you are in violation anyway. So, when you bond it properly, you will be using an electrode mentioned in #1, therefore you will not be required to meet the 25 ohm rule. Or remove the made electrode and you're back to no 25 ohm requirement.
6. Assuming there wasn't an electrode mentioned in #1 and you were using 1 made electrode only you must meet the 25 ohm test.
7. If using 2 made electrodes at least 6 ft apart you are not required to meet the test.
It kinda seems like a circle jerk
I added up time and effort long ago and now stick with 1 made rod & metal water pipe. It works every time. My material and labor is consistent every job and no greif.
[This message has been edited by TE (edited 08-28-2002).]
Re: Concrete Encased Electrode?#81556 08/28/0206:33 AM08/28/0206:33 AM
Got to start somewhere! I am familiar with the test you mentioned.
It should also be noted that we are familar with, and understand the NEC GEC requirements, and that the term "MADE" has been removed from the 2002 NEC. Rods, etc., are now considered as electrodes too.
[This message has been edited by Joe Tedesco (edited 08-28-2002).]