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eHam Forums => Antennas, Towers and more => Topic started by: K6RQR on April 21, 2017, 06:45:28 PM



Title: Copper for ground rods
Post by: K6RQR on April 21, 2017, 06:45:28 PM
Hello All -
 I will be installing several copper ground rods and I was wondering something. The copper rods I will be using have been exposed to the weather and have the usual oxidation on the surface. Would it be better if I polish that off before I drive them into the ground? In other words, is there any increase in their effectiveness by removing the layer of oxidation? Thanks.

73,
Bruce  K6RQR


Title: RE: Copper for ground rods
Post by: K0ZN on April 21, 2017, 06:51:28 PM

 Driving them in the ground will "clean" them!  Dirt is quite abrasive. 

The most I would do is just make sure there is no grease or oil on them.
 FYI:  I have found that "sharpening" the end more than the factory does, *can* make it a little easier to drive them.

  73,  K0ZN


Title: RE: Copper for ground rods
Post by: KE6EE on April 21, 2017, 07:17:57 PM
Polish them to a high shine.

Wax them with high quality automobile polish.

Drive them into the dirt with a big hammer.  ;D
 
(Hint: driving ground rods is usually much easier when there is water continually running along the rod.)  8)



Title: RE: Copper for ground rods
Post by: K1HMS on April 21, 2017, 07:52:48 PM
Suggestion: Go to home depot and rent the largest hammer drill they have. Make sure the chuck is big enough to fit over the ground rod. At $35 for 4 hours it is worth it.

You can bury a 8' rod in a minute or two. Here in NH its rocky and there is a thin layer of Granite every few feet. I start up a step ladder and almost cant get down it fast enough.

When it is this easy it is easy to put several longs rods in. Just make sure there isnt a septic, gas pipe or buried electrical in the rod's path....


Title: RE: Copper for ground rods
Post by: K0ZN on April 21, 2017, 09:38:50 PM

 K1HMS is absolutely correct!  Rent a large hammer drill.....and put in several rods about 8 ft. apart. 
 Driving an 8 ft. ground rod by hand is real work.

  73,  K0ZN


Title: RE: Copper for ground rods
Post by: WA7PRC on April 21, 2017, 09:48:43 PM

 K1HMS is absolutely correct!  Rent a large hammer drill.....and put in several rods about 8 ft. apart. 
 Driving an 8 ft. ground rod by hand is real work.

  73,  K0ZN
Demolition (aka 'jack') hammer, not hammer drill. In 2011, I rented a 60# demo hammer w/ ground rod adapter to sink several 10' ground rods in "glacial till" soil. If I used a wimpy hammer drill, I'd still be trying.


Title: RE: Copper for ground rods
Post by: NK7Z on April 22, 2017, 03:50:11 AM
Suggestion: Go to home depot and rent the largest hammer drill they have. Make sure the chuck is big enough to fit over the ground rod. At $35 for 4 hours it is worth it.

You can bury a 8' rod in a minute or two. Here in NH its rocky and there is a thin layer of Granite every few feet. I start up a step ladder and almost cant get down it fast enough.

When it is this easy it is easy to put several longs rods in. Just make sure there isnt a septic, gas pipe or buried electrical in the rod's path....
Best advice I have seen here so far...  I used one, and it takes all of 10 minutes to drive an 8 footer here.  Normally, it is a 30 to 40 minute job.  Much nicer on the user as well...


Title: RE: Copper for ground rods
Post by: K0BT on April 22, 2017, 10:02:28 AM
Thanks for the great suggestion!  I dreaded adding more rods after using a fence post driver to hammer through the caliche and river rocks.


Title: RE: Copper for ground rods
Post by: WA7PRC on April 22, 2017, 10:12:43 AM
MOST of my rods went right in, in a matter of seconds. Some took about a minute. One rod sank about halfway and STOPPED. It took several minutes before the rod broke through. IOW, the amount of time and effort varies, dependent upon what's in the soil. Use a demolition hammer, not a hammer drill.


Title: RE: Copper for ground rods
Post by: KL7CW on April 22, 2017, 11:19:27 AM
Last summer I finally decided to put in a good lightning ground system around my towers and also to beef up the unknown quality of the electrical ground near the utility entrance.  I had previously put in ground rods with a hammer and fence post driver....not always easy in our rocky ground.  I looked at some hammer drills...might have been OK, but instead chose an electrical powered medium size jack hammer with a ground rod attachment.  I was working alone, so was worried about standing up on a ladder with the heavy jack hammer, and did not want to construct scaffolding for all the rods.  Instead I just used my post hole digger to go down perhaps a foot or so.  Then I used the fence post driver to go down another few feet until it became difficult.  I then used the jack hammer to drive down the rod to the desired depth.  I rented the jackhammer, fence post driver, the ground rod tool from the local tool rental place. I think the rental cost for the ground rod attachment was $10, and the fence post driver was not much more.  The large jackhammers are very heavy...too heavy for this 76 old guy working alone...so rented one of the smaller ones...still quite heavy.  It worked great, almost like a hot knife cutting through butter.  I think the jack hammer rental was only something like $50...not sure.  I was quite tired at the end of the day, and if I ever need to put in another 8 rods, I will bribe a few of my husky teen age grandsons or ham friends to help....a few pizzas do not cost much. 
    Rick  KL7CW  Palmer, Alaska     where glaciers deposited many rocks eons ago,  but where lightning is nearly non-existent !!!!!


Title: RE: Copper for ground rods
Post by: K6RQR on April 22, 2017, 07:00:14 PM
Hello All -
 One earlier question I had was about whether to polish the copper rods because mine have a coating of oxidation. The answer is definitely yes. I just finished cutting the 4 pieces and I decided to test them with a multimeter. When I applied one probe to a part of the end that has been recently cut and then applied the other probe to a place farther down the rod I got no connectivity. Simply applying some pressure to that probe on the surface restored the continuity. So, I will definitely polish the rods for maximum conductivity with the soil. I have a nice 1" wide ground strap that will serve to connect the rods together and be fastened to the back of my rig. I'm hoping that the combination of this ground system and the 1:1 isolation balun coming from Balun Designs will put a real dent in the QRN around here.
 Again, thanks for all the comments.

73,
Bruce  K6RQR


Title: RE: Copper for ground rods
Post by: AA4PB on April 22, 2017, 07:23:56 PM
Usually, driving them into the ground will remove the oxidation just like you cleaned it. Most ground rods are copper plated steel so you don't want to grind away all of the coper plating.

When you rent the demo tool, be sure to get a ground rod bit for it. The bit slips over the ground rod and will keep you from flaring the end of the ground rod making it difficult to slide a clamp onto the rod. If you use a hammer, put the clamp on first before you start beating up the end of the rod.


Title: RE: Copper for ground rods
Post by: K6AER on April 22, 2017, 07:28:29 PM
You cannot test ground rod conductivity with a ohm meter. You must use a Megar or ground rod test meter such as a AEMC unit.


Title: RE: Copper for ground rods
Post by: K1HMS on April 23, 2017, 05:28:50 AM
Demo drill vs hammer drill

Is a demolition drill better, YES. The smallest they had was over 40 lbs, required me to buy a $47 bit, and it plugged into 220VAC so i would have rented an extension cord.  IF the rental store has one you can use, it is the way to go. If you have more than 2 rods it might be worth the expense.

But a hammer drill still beats a post pounder or sledge hammer.  There are numerous you tube videos of people using both.

I wouldn't do it but to stay off a ladder Ive seen people drive in a 4 footer and with a threaded coupler add another 4 footer and drive it in for 8' total.

Hamilton


Title: RE: Copper for ground rods
Post by: W8JX on April 23, 2017, 05:50:48 AM

 FYI:  I have found that "sharpening" the end more than the factory does, *can* make it a little easier to drive them.


Actually a chisel tip or angle cut on end works better than a point. It cuts through rocky soil better than a point.


Title: RE: Copper for ground rods
Post by: K6RQR on April 23, 2017, 08:02:55 AM
To K6AER -
 I'm not trying to measure ground conductivity with an ohmmeter. I was just checking to see that the potential conductivity of the ground rod in the soil was maximized by the surface of the rod being polished. The ohmmeter apparently confirmed that the oxidation on its surface was an impediment to that.

Bruce  K6RQR


Title: RE: Copper for ground rods
Post by: AA4HA on April 23, 2017, 08:30:47 AM
Usually when setting an array of ground rods the proper spacing is the sum of the lengths of both rods; If you have two, eight foot rods, the spacing should be sixteen feet.

The idea being that the rods should be separate enough that they are outside of the zones of influence of each other to maximize the conduction area to the earth. It is more than just how many square inches are in contact with dirt, it is the entire area around the rod that is forming part of the ground system.

Depth is important to reach a point where the soil moisture levels are consistent; Typically the first foot or so of earth is subject to the seasons, freeze-thaw and rain-drought. But you can also end up falling for the "mo is betta" trap of trying to put in a 100 foot ground system, thinking that it is ten times better than a single, ten foot ground rod. An overly long single ground rod actually has an inductive effect that will delay the discharge current and increase the probability of damage.

I would not wax ground rods; you are taking something that you want to be a good conductor and covering it with a substance that is an electrical insulator? You can make a ground rod nice and shiny but it is going to oxide back up in a matter of hours after you drive it (just the way that chemistry works). All you will have accomplished is to reduce the thickness of the copper plating on the ground rod.


Title: RE: Copper for ground rods
Post by: KE6EE on April 23, 2017, 10:09:33 AM
I would not wax ground rods.

Nor would I. I forgot to add the smiley to my recommendation.  ;D


Title: RE: Copper for ground rods
Post by: KL7CW on April 23, 2017, 10:20:57 AM
HMS,
     I do not know why your rental place did not have a 120 volt reasonable size domo (jack hammer).  I live in a very small town and the rental place (I think part of a national chain) had at least two of them.  They knew all about ground drive bits and rented me one for $10.  Originally a BIG guy rolled out a monster machine...I said NO.  They then brought out a somewhat smaller machine which I could at least lift.  I think it had some sort of strange plug on the end, but they included a free adaptor for a regular 120 volt extension cord.  My normal size extension cord worked fine with my standard 20 amp breakers.  Before this I called a few other places and they also had similar machines and knew all about ground rod bits which they rented.
     It was not too hard to get an 8 ft ground rod started....just climbed up a bit on a ladder and pounded it in a little, then used a fence post driver to pound in a few more feet.  At this time I could lift the jackhammer over my head either from the ground...some rods, or from a platform about two feet high.  I could not reach the on-off switch on some of them so had my wife just plug it in and soon I could reach the switch myself.  The hammer was heavy for me, but I am 76 years old and not especially strong, but it should be easy for younger husky folks. With two people it should be very easy.
     I am not saying this method is best...just saying it worked fine for me in our rather rocky soil.  I do not remember how heavy my machine was, but am sure it was at least 40 pounds....it felt very heavy.
                 Rick   KL7CW


Title: RE: Copper for ground rods
Post by: AA4PB on April 23, 2017, 11:02:11 AM
I purchased a 40lb jack hammer on closeout from Harbor Freight for $130 several years ago. It works fine to drive an 8-foot ground rod. I have someone on the ground steady the ground rod while I get on a step ladder with the jack hammer to get it started. In this soil, it only takes a few minutes to put in an 8-foot ground rod.


Title: RE: Copper for ground rods
Post by: K6RQR on April 23, 2017, 11:39:08 AM
AA4HA -
 Is it really true that the rods will oxidize back up in a matter of hours after they are driven into the ground? That doesn't seem right to me. Have you experienced this? I'm not saying that they wouldn't develop a layer of oxidation eventually but it seems unlikely to me that it would happen so fast.

73,
Bruve  K6RQR


Title: RE: Copper for ground rods
Post by: W8JX on April 23, 2017, 12:12:37 PM
Usually when setting an array of ground rods the proper spacing is the sum of the lengths of both rods; If you have two, eight foot rods, the spacing should be sixteen feet.

The idea being that the rods should be separate enough that they are outside of the zones of influence of each other to maximize the conduction area to the earth. It is more than just how many square inches are in contact with dirt, it is the entire area around the rod that is forming part of the ground system.

Funny thing is the power company drive one rod straight in fans 3 or 4 more ground rods out  driven at abt a 45 to 60 degree angle from ground level from a central entry point and then ties them together here installing grounds for power pole transformers by houses


Title: RE: Copper for ground rods
Post by: KM1H on April 23, 2017, 12:23:37 PM
Suggestion: Go to home depot and rent the largest hammer drill they have. Make sure the chuck is big enough to fit over the ground rod. At $35 for 4 hours it is worth it.

You can bury a 8' rod in a minute or two. Here in NH its rocky and there is a thin layer of Granite every few feet. I start up a step ladder and almost cant get down it fast enough.

When it is this easy it is easy to put several longs rods in. Just make sure there isnt a septic, gas pipe or buried electrical in the rod's path....

Not in my part of NH where solid ledge is common except in the lowest areas and swamps!!  I hired a dynamite blaster in order to situate the foundation. And the well digger hit ledge at 2' and had to go 600' for water; the joys of living on top of a hill but it is a killer for DX and VHF and above ;D   Some on this hill went to 1500' and came up dry which is why the homes are few and far between.

Almost horizontal is the only way that works for the ground rods here. Guy anchors for the towers were drilled in 8' using a mobile compressor and a 2" diameter drill bit. Then 8' utility company grade rock anchors installed, locked in place, and then epoxy poured in.

Carl