What the Hell !!!

As you know I live on a hill of red clay. I might as well live on top of a high voltage insulator. Two copper ground rods spaced one foot apart ( installed ten years ago), now show an infinite impedance between the two. I just drove a new 8ft galvanized ground rod 5 feet from the copper ones and not surprisingly, I created a battery between one of the copper rods and the galvanized, I get 0.6 volts DC. It ticks me off that I cant get a decent ground, I don't know what to do. I'm tempted to pour rock salt around the rods but I think that would just corrode the metal or oxidize the copper. It appeared that the copper rods had oxidized and after I pulled it up 6 inches with a farm jack, I got better continuity. The soil was wet from rain when I made these tests. There is a high content of iron in my well water and iron in the gravel of my driveway (you'd think that would help). I think the only real ground I have is the 20 feet of 6" iron pipe in the top of my well. Any suggestions?

Reply to
n
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attach ground wire to well

Reply to
TimPerry

First off, the rule of thumb is that two separate ground rods should be installed at least the length of the ground rod apart to be effective. I think this is in the IEEE Green Book. Secondly, the metal well casing is permitted to be bonded to the grounding electrode system ONLY IF the well casing is not effectively bonded to a metal water pipe (new to the 2005 NEC.) See 2005 NEC Section 250.52(A)(7) below.

Several years ago I inspected a grounding electrode system used atop a mountain for a NEXRAD site that used 19 - 20 foot long ground rods installed in drilled holes at the perimeter for the site. They were bonded together to form a grounding electrode grid. However, the single connection to this grid from the service was installed in a metal conduit that was not bonded to the grounding electrode conductor at the ends. I wrote this up as an observed anomaly because it violated the IEEE green book and the NEC. The three communication engineers had to call home base and go through a one day consultation period before they would correct the problem.

But in the real residential world, in interior Alaska where I live we have frozen ground for 8 months out of the year. Frozen ground offers very high resistance to ground rods, but we just drive one ground rod and hope for the best. Fortunately, frozen ground also offers a great deal of safety. I have stood on frozen snow covered ground and held a hot 120 volt wire and I was so insulated that I don't get shocked.

250.52(A)(7) (7) Other Local Metal Underground Systems or Structures. Other local metal underground systems or structures such as piping systems, underground tanks, and underground metal well casings that are not effectively bonded to a metal water pipe.
Reply to
electrician

Use equipotential mesh imbedded into GEM (Ground Enhancing Material)

See:

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Gene

Reply to
EpsilonRho

We had to use an acetylene torch to heat copper ground rods to drive them at Ft. Greely back in the early '70s because of stray RF problems at the AFRTS radio & TV station where I worked. We would heat the rod, drive it a few inches till it cooled off, pull it out and repeated till we finally broke through the permafrost, then drove another 20 feet of rod for the actual ground.

We had so much stray RF in the TV control room that we couldn't find a clean telephone line, and we couldn't use the telephone interface for live radio feeds because of the feedback. I also pulled out over a mile of abandoned telephone, audio and video cables out of the attic of the wood building to finish the job.

Reply to
Michael A. Terrell

Seems to me a metal casing is REQUIRED to be bonded if not bonded to a metal water pipe. If it is bonded by a metal pipe it MAY be separately bonded.

bud--

Reply to
Bud--
< We had to use an acetylene torch to heat copper ground rods to drive them at Ft. Greely back in the early '70s because of stray RF problems at the AFRTS radio & TV station where I worked. >

Yes, Ft. Greely is one cold and frozen place. I graduated from high school there in 1962. I remember the winter of 61-62 when it was 62 F below zero for two weeks at our homestead near there. We burned wood and it took three birch trees a day to stay warm in our log house. We did have electricity though, for the light bulbs and radio. I don't remember if my Dad put in a ground rod at all for our service. I do remember seeing a lot of pennies in the fuse box. When it is 62 below, electrical safety takes a back seat to staying warm.

Reply to
electrician

Here is the original propoasl from the 2005 NEC Report on Proposals:

5-134 Log #1617 NEC-P05 (250-52(A)(7)) Final Action: Accept Submitter: Lanny Hughes, Washington State Department of Labor & Industries Recommendation: Revise 250.52(A)(7) to include underground metal well casings to read as the following: 250.52(A)(7) Other Local Metal Underground Systems or Structures. Other local metal underground systems or structures such as piping systems, underground tanks and underground metal well casings, not effectively bonded to a metal water pipe. Substantiation: By including a well casing described above to 250.52(A)(7), it would more clearly be defined as an Other Local Metal Underground Systems and not as an underground metal water pipe, as in 250.52(A)(1), thereby eliminating the requirement in 250.53(D)(2), to additionally to install a supplement electrode. Many Authorities Having Jurisdiction are interpreting a stand-alone well casing (connected to PVC pipe) as an underground metal water pipe system, because it is mentioned in 250.52(A)(1), (when it is effectively bonded to a metal underground water pipe) thus requiring a Supplemental Electrode. A metal well casing that is not effectively bonded to a metal water pipe should be able to stand on its own merit as an grounding electrode without the requirement of a supplement electrode. By placing it under 250.52(A)(7), it would not be required to be used as an electrode if available, only as an option if electrodes specified in 250.52(A)(1) through 250.52(A)(6) are not available, as mentioned in 250.50. Well casings are normally the best electrodes available. They either meet or exceed the code requirements for electrodes. The Dept. of Ecology requires at least 20 ft of 6 in. metal casing, (2 ft above grade plus 18 ft below grade) for protection from damage. The corrosion protective coating on new well casing is so thin that most of it is scrapped off when it is driven into the ground. Most casings will rust below grade thus increasing its continuity to earth. Recently, I have inspected several cell sites in sandy locations that have not been able to attain the 5 ohms or less to earth ground, as required by the Telecom industry specifications. These sites all have an extensive ground grid system consisting of at least 5 or more copper ground rods and hard drawn tinned copper electrode conductor. The only way they were able to attain the required 5 ohms or less, as required, was to run an electrode conductor to a nearby well casing. After using the well casing as an electrode, they measured 0 ohms from the cell site to earth ground (Actual measurements could be submitted if necessary). Panel Meeting Action: Accept Editorially change the proposed text to read: "Underground metal well casings which are not effectively bonded to a metal water pipe."
Reply to
electrician

I remember walking the two miles each way, from my barracks way to the TV station and back when it was -60 degrees. Most people call me a liar. They don't believe just how cold that place could get. I would roll my chair over next to the TV transmitter while waiting for the next film change and wear a heavy coat and gloves while operating the station on those cold, windy days. It was barely above freezing in the old WW-II wood building because there was no insulation, and a metal roof over a thin fiberboard ceiling. I took survival training at about -30 for three days out in the open. We would drop-kick a sapling to snap it off about a foot above the ground and throw the entire tree into the fire. You could stand ten feet from a roaring fire and barely feel the heat, and the fire could burn out to cold ashes in under 15 minutes. I also remember fighting a forest fire in the "Buffalo Drop Zone" outside of the base in 1974.

Reply to
Michael A. Terrell

Hey, thanks so much for the comments and the PDF file. I live near Eugene Oregon we're having 50 degree temps and lots of rain. More questions: That

0.6 VDC between the copper and galvanized rods will eventually cause corrosion problems right? I hear that the Alaskan pipeline uses batteries of an equal but opposite polarity to neutralize the current flow so the metal doesn't rust or become a sacrificial electrode. If I bond to the well casing (20ft, static water level is 50 ft down) (I am using PVC for the water line) I can weld a steel tab that will then have a wire lug bolted to it (say 60 feet of 8 gauge copper wire?) this can then split bolt camp to the aluminum neutral wire on the overhead service drop from the meter pole. I know this will not work for a lightening strike but it is the shortest distance to the meter ( the well is about 150 feet from the house). Problem is the high humidity and rain mixing with dissimilar metals, again causing more corrosion. What to do... In the future, I'm thinking of renting a ditch witch to dig 3 feet down and making a grid and placing ½ inch copper pipes in the grid, using silver solder at the joints inside a perimeter of 40ft by 40 ft in the yard near the site of my new home that I expect to build. How close should the grids be, 5x5ft?

I can rent a spot welder to bond copper wire to the copper pipe (or more silver solder).

Reply to
n

I had remebered all existing electrodes 250.52A-1 to 7 were required to be bonded but only 1-6 are with 7 optional so you are correct its inclusion is permitted not required.

I would nit pick slightly that a casing may be separately bonded to the electrode system if the casing is connected/bonded to metal water pipe, but that separate bonding does not count for the casing to be a suplemental electrode to the water pipe. (I think this is not logical. A casing can be used as the sole electrode if connected with PVC but if it is connected to metal water pipe and also separately bonded you need a different supplemental electrode for the water pipe?)

The ground resistance of the casing in the substantiation is quite interesting.

I have read that a CD for the proposed changes/initial comments and a CD for the final action is available from the NFPA. Do you know what the process is to get them? I have looked at some of the older printed copies and, as above, there is interesting info burried therein (along with a few bizzare ideas).

bud--

Reply to
Bud--

The Report on Proposals and the Report on Comments were available for free in pdf format from the NFPA web site, but I don't know if they still have them. I have them but the total file size is quite large or I would up load them. I think the well casing can be used as the sole grounding electrode without a supplemental grounding electrode if NOT connected to a metal water pipe. If the well is connected to a metal water pipe the water pipe shall be connected to the grounding electrode, but a supplemental grounding electrode is required because so many times later on some or all the metal water pipe may be replaced with a nonconductive nonmetallic pipe. In other words the metal water pipe cannot be depended on as a permanent connection to the well casing. But I don't see anything that does not permit the well casing from being bonded to the grounding electrode in either case. So for good measure, why not connect to the metal water pipe and the well casing?

Reply to
electrician

Now you have opened a bucket of worms: Cathodic Protection. First some hindsight into experience since I am an old geezer I have lots of it. Back in about 1988 I inspected at the Red Dog Mine Port Site about 70 miles north of Kotzebue in Alaska. The ocean floor was so unstable that they had to build cells in the water to make a port. This involved driving steel pilings and filling the hole with gravel. The pilings were protected from corrosion using a dc rectifier and a sacrificial anode. The negative was supposed to go to the metal pilings, the cathode, and the positive to the anode. Unfortunately, someone hooked it up backwards and after about three months a buoy about a mile away floated off from its anchor. After capturing the buoy they found that the anchor chain had been literally eaten away. HMM...Well some bright engineer said I know what happened some one connected the cathodic protection in reverse and sure enough that is what they found. Now about the Trans Alaska pipeline. Two types of cathodic protection are used, passive and active using rectifiers. I have worked on the active but the passive was done by laborers since no induced current was used and the laborers union grabbed the work. For the active, we used a DC rectifier and connected the negative to the pipe using a cad weld procedure and the positive was connected to a very long anode embedded in a coke powder and wrapped with a sort of mesh. This anode was buried for miles along the pipe about 4 feet away in a trench. The anode conductors were spliced into this at various locations to insure that an equal positive charge was distributed along the pipeline in the fill. I have had the fortunate (or unfortunate experience) of having worked on these systems both on the pipeline and at the Valdez marine terminal. Unfortunately there are no NEC code rules for these cathodic systems like they have in the Canadian Electrical Code (CEC.) The CEC has some rules on labeling and identifying these systems in the field. Sure enough at the Valdez Marine Terminal the Cathodic Protection single conductors have been mistaken for grounding conductors on more than one occasion. There have been proposals to add Cathodic Protection to the NEC but so far they have not been adopted. Now in your case, I would definitely bond the well casing to the grounding electrode and attempt to bond the rebar in the foundation (if you have one) to the grounding electrode. It would have been better to have installed a copper ground wire and have bonded it to the rebar by wire wraps or compression fittings made for that purpose before the concrete was poured and then bond that to the grounding electrode. This Eufer ground as it is called is one of the best grounding electrodes that you can make and from my research is used extensively in the Southwest US where there is much lightening. If you are on top of a mountain as you stated I would suppose you are going to have some lightening hits on your service.

Reply to
electrician

Well, I've had lightening strike about 80 feet from the site of my new home. Hell of a akBOOOOM! I'm 150 feet above the valley floor and the hill climbs another 200 feet above me, all red clay ( I'm on a plateau). Since the concrete has not been poured yet, I can arc weld all rebar, joining them together. Not real sure how I can melt copper to rebar except for a spot welder. The well casing will not help in a lightning strike unless I trench a direct path from the new foundation to the casing and bolt a copper wire to it , the size may not be a 1/0 because around here, only aluminum is sold in that size. That leaves a bolt and lug which will corrode over time. I think rebar is pig iron and casing is steel, is that a dissimilar metal? Actually you confirmed that grounds have a very limited lifespan.

.
Reply to
n

You are not supposed to use aluminum in direct contact with earth or within 18 inches of earth per code- too corrosive.

Reply to
electrician

I found your story very interesting. My only personal experience with active cathodic protection was watching a Union Oil employee check out the resistance on a protected pipeline..

I do remember, however, in my introductory EE book by Dawes, there was a section about electrolysis of street car tracks.

Bill

-- Ferme le Bush

Reply to
Salmon Egg
< found your story very interesting. My only personal experience with active cathodic protection was watching a Union Oil employee check out the resistance on a protected pipeline..

I do remember, however, in my introductory EE book by Dawes, there was a section about electrolysis of street car tracks. >

The engineers on the Trans Alaska Pipeline that do the cathodic protection systems are mostly civil engineers. I have never figured that out except that the electrical is really quite limited. Even the "humphee" wire used for direct burial for the DC conductors is not listed. It is one very tough insulated wire and probably beats USE all to hell, though. The civil engineer for the Valdez Terminal was very efficient and saved Alyeska Pipeline Service Company a lot of money. He was well known for cutting costs in this area. This is very interesting since just today in the Fairbanks Alaska Daily News Miner a Federal whistleblower has reported that Alyeska inflated the numbers in what has been spent for corrosion control for the pipeline. The recent 1/4 inch hole in a pipe on Alaska's North Slope that leaked about 350,000 gallons of crude unto the tundra has reignited the corrosion protection problems of the pipeline. The fact is, without a very good cathodic protection system the underground part of the pipeline would be gone by now. And there is considrable pipe buried. It is where the cathodic protection was not installed or improperly installed that the problems occur. My experience in this area tell me that these systems were not that well done and we can expect more holes and leaks to occur in these oil lines as time passes. Alyeska has laid off numerous excellent engineers and seems to have gone astray in the engineering arena. The news miner story is at:

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Reply to
electrician

I should also add that when the Trans Alaska pipeline pipe was coated at the Fairbanks, Alaska coating plant in about 1975-76 the electrician working there was told to lower the cure temperature so they could get higher output. And that he did. This coating was supposed to inhibit corrosion. He told me about this soon after the corrosion problems occurred at the Brooks Range Atigun Pass crossing about 13 years ago. At Atigun pass the buried pipe was corroded because the water had gotten under the coating. I wonder how Rep. John Dingel would like to hear abbout this?

Reply to
electrician

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