Which cycle do you want referenced. It has always been a requirement that at least 25 ohms of resistance or two rods. For 2008 see 250.56 and in the 2011 see 250.53(A)(2)Quote:
Originally Posted by big2bird
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Which cycle do you want referenced. It has always been a requirement that at least 25 ohms of resistance or two rods. For 2008 see 250.56 and in the 2011 see 250.53(A)(2)Quote:
Originally Posted by big2bird
Yes, 25 ohms or less is the requirement. There is no automatic requirement for two. When updating a service entrance, most local inspectors will know the soil resistance as measured by a biddle tester, and will instruct you as to their requirement.Quote:
Originally Posted by jwelectric
For the most part, sandy/dry soil is the enemy. Beach and desert areas will most often require two.
The 2011 cycle states that two rods must be installed unless the electrical contractor hires a Professional Engineer to perform the test.Quote:
Originally Posted by big2bird
The clamp on testers only read the ground loop between the grounding electrode on the premises wiring and the supplying transformer grounding electrode. This is not earth resistance.
I have been in the electrical field for more than 44 years and have never known an electrical inspector to perform any type of electrical test especially on the grounding system. The resistance of the grounding electrode will vary with weather conditions so a test done today will be different than one done tomorrow.
As an electrical inspector for NC should I come out and see only one rod at any location then the electrical contractor will have to produce a written report from a Professional Engineer and I will not accept the results of only one test.
EDITED TO ADD;
Here is the only test that counts
http://www.esgroundingsolutions.com/...tance-test.php
I guess I am behind the times. I bow to your up to the minute knowledge.We are still working off of the 2010 here in most all building departments.Quote:
Originally Posted by jwelectric
BTW, by a Biddle earth tester, I mean the meter you use attached to two test probes 6' apart. I generally have to get third party certification on any public works project. Testing between the SE and the utility ground would be irrelevant.
I just read that link. Basically, it makes it more cost effective to add a second ground electrode than to test. It would be easier to just mandate it, and be done with it.
ok, I got the double lug problem resolved at service disconnect just below meter at pole.
I found the neutral that was in the barn. Indeed, it was just run a ground rod. I'm in the process of pulling a new conductor for neutral in barn.
The existing conduit w/ the exising #4 conductors is 1" sched 40 pvc. Smaller than I'd like, but I think I get the 4th conductor in there.
My problem remains in the barn, I had an existing 100a main breaker panel (square d w/ many breakers), but will be oversized to protect that #4 au. For various reasons, I'd rather not dig up the 200ft of existing #4 and I can't find an 80a main breaker.
So, can I put in a disconnect w/ 80a breaker to feed the 100a main I already have?
Yes, protect the conductors where they originate and if they are #4 then a 50, 60, 70, or 80 amp breaker will work and it doesn’t matter what size breaker that is in the panel at the barnQuote:
Originally Posted by backwaterdogs
I think you will find that quite difficult.Quote:
Originally Posted by backwaterdogs
you're right, i messed w/ trying to pull that #4 thru the existing 1" for awhile...I couldn't even get a fish tape thru the 100' of conduit.
So, I have pulled out the exsiting #4 conductors (actually, 1 was bigger, #3 or #2) and lining up a trencher to cut a trench and put down new, bigger conduit. i'm now faced with another decsion:
1) Put in the 100' of 2"+ conduit and re-pull the existing #4 copper that I have. This will only cost me another 80a breaker and box at pole to protect the #4.
2) Put in #3 copper (haven't priced al. yet) so I have full 100a capacity should I ever need it. This will cost me 300' of #3 copper conductor at over $125/ft. I could probably sell the $4 I have to defray some of the cost.
I started this project to get the service in my barn safe at minimal expense, which seems to point to option 1, but I do like the idea of having service appropriately size for 100a, altough I don't see me utilizing it.
Any thoughts? thanks!
Yes. I would invest in option #2. You could use one of your existing 4's as a ground.Quote:
Originally Posted by backwaterdogs