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KE2KB 03-13-2013 03:56 PM

Unable to install ground rod
 
Hi;
I tried to install a 2nd 8ft x 5/8" copper clad steel ground rod today but failed after getting it down about 6 inches.
It was going to be about 8" from the foundation of the house, along the side directly below my amateur radio antenna. I just wanted to add a rod for the antenna, which would be bonded to the main rod for the electric service.

The top surface is asphalt. The driveway comes right up to the foundation. I was able to get through that. But after getting nowhere with the 8ft rod, I tried a shorter section of 1/2" rod I had; just to test the soil. I could not drive that rod any farther into the ground, so I abandoned the project.
I had been using a 3lb sledge hammer, with the rod supported through a wood step ladder to prevent it from moving too much. I also tried the 2x4 with a 3/4" hole drilled for more support, but just could not get to go anywhere.

I have several thoughts on this:
1) I am too close to the foundation. I don't know what lies below the ground close to the foundation, but I have read about rock fill that is often used, making it difficult or impossible to drive a rod, and to get an acceptable resistance to ground at such a location. That said, the main rod for the electric service is located only about 5 inches from the corner of the foundation, next to the meter.

2) Before the asphalt driveway was put down, there was a concrete sidewalk next to the house. But I thought that had been removed before the asphalt had been laid. It seems that it must have been, since the asphalt is perfectly level all the way to the foundation.

I poured water into the hole, then jammed the shorter section of rod into it. That resulted in mud coming up, so at least I know that I did hit earth.

Even though I live in NJ, I don't think the ground is frozen hard enough to prevent the rod from going more than six inches. I tried the short rod in another area, away from the house, and it went in easily.

The house is 80+ years old.

Any ideas?

Thanks

FW

ddawg16 03-13-2013 04:17 PM

You may have found the only big rock in the yard....

Find another spot....or get out the hammer drill and punch a hole......and hope it's not the water, gas or sewer line.....

Just don't do like some....cut the rod so that it's only 12" long...and shove in 6" to make it look like you have in all the way in the ground.

Bondo 03-13-2013 04:29 PM

Ayuh,.... An electric hammer drill driver will sink that rod, Quicker than ya can read this post...

That said, I'm guessin' #2 is the answer,...
The blacktoppers probably shimmed the area with stone over the ole concrete, 'n paved the result...

I'm a blacktopper, 'n it's done All the time...

I donno if the electric hammer drill driver will sink that rod through a chunk of concrtete or not, never tried it,...
But I know it'll drive that ground rod through compacted frozen ground... stone or otherwise...

I've got a cheapy imported driver, 'n the ground rod slips right into the bit driver,...
I take out the drill, or chisel, 'n drop it over the rod,...
Pull the trigger, 'n the rod Disappears... ;)

KE2KB 03-13-2013 05:10 PM

Hi guys;
Thanks for your replies;
It would figure that I hit the biggest rock!
Unfortunately, I don't have a hammer driver. Maybe I can rent one.
Maybe I'll get one of those smaller ground rods from Radio Shack (the 4ft 1/4" or 3/8" ones used for TV antenna) just to test for rocks. I don't want to keep making larger holes in the blacktop until I find the right spot.

Incidentally, I just measured the resistance to the main ground rod and it reads 0 ohms on my DMM. It's been raining recently, and before that we had some snow on the ground. I guess I should measure it again after it's been dry for a while.

FW
Edit: I think I can use a length of rebar to test for rocks. At least then I won't be making such large holes.

Glennsparky 03-14-2013 03:20 AM

You can't use a digital multi meter to measure a ground rod. The readings are meaningless. You can use a megger (megohmmeter), but it's difficult, labor intensive and involves math. Or you can use an Earth Ground Clamp Meter that costs one or two thousand dollars.

And, yes, rain will effect the readings.

bobelectric 03-14-2013 08:06 AM

Use a demo hammer with a ground rod driver. Any electrician should have one.

KE2KB 03-14-2013 04:36 PM

Quote:

Originally Posted by Glennsparky (Post 1136921)
You can't use a digital multi meter to measure a ground rod. The readings are meaningless. You can use a megger (megohmmeter), but it's difficult, labor intensive and involves math. Or you can use an Earth Ground Clamp Meter that costs one or two thousand dollars.

And, yes, rain will effect the readings.

I wonder whether the electrician who installed our service tested it. According to code, one ground rod is not sufficient. But the copper water line is also bonded to the GEC via the ground buss in the panel.

FW

stickboy1375 03-14-2013 05:32 PM

Quote:

Originally Posted by KE2KB (Post 1137313)
I wonder whether the electrician who installed our service tested it. According to code, one ground rod is not sufficient. But the copper water line is also bonded to the GEC via the ground buss in the panel.

FW

You still need two ground rods to meet code, but some people consider them house anchors anyways... I would not lose an once of sleep over one or two rods driven. I just install two because im paid to meet code. ;)

vsheetz 03-14-2013 09:19 PM

Rent/borrow a good sized hammer drill - if you still can't drive it there is an obstacle - find another location.

W6CD

redman88 03-14-2013 09:29 PM

is 8" far enough from the foundation? might your footer for the foundation be that wide?

KE2KB 03-15-2013 09:14 AM

Quote:

Originally Posted by redman88 (Post 1137496)
is 8" far enough from the foundation? might your footer for the foundation be that wide?

You've got a point. I don't know. The house is more than 80 yrs old.
I don't want to go out any farther with the rod though; It would be an obstacle someone could trip over. Perhaps if I completely bury it, but then I have to make a small trench in the asphalt for the wire.
Perhaps I could try going in at a slight angle away from the house?

FW

stickboy1375 03-15-2013 04:47 PM

Quote:

Originally Posted by KE2KB (Post 1137713)
You've got a point. I don't know. The house is more than 80 yrs old.
I don't want to go out any farther with the rod though; It would be an obstacle someone could trip over. Perhaps if I completely bury it, but then I have to make a small trench in the asphalt for the wire.
Perhaps I could try going in at a slight angle away from the house?

FW

Code requires the ground rod to be completely buried.

KE2KB 03-16-2013 02:06 PM

Quote:

Originally Posted by stickboy1375 (Post 1138014)
Code requires the ground rod to be completely buried.

Then technically, the one that is installed at the corner of the house near the meter is not meeting code. I can still see and access the acorn nut, as it is located above ground by about 1".

I was thinking that I could bury my new ground rod farther away from the foundation, then cut a small "trench" for the wires to reach it from where they run along the foundation.

Is there a special type of wire I must use if I am going to bury it?
I believe what I have coming off the antenna mast is #4 THWN, but not sure. It could be just THHN. But since it's a GC, it shouldn't need any insulation in the first place, correct?

FW

Glennsparky 03-18-2013 06:02 AM

Quote:

Originally Posted by KE2KB (Post 1138644)
Then technically, the one that is installed at the corner of the house near the meter is not meeting code. I can still see and access the acorn nut, as it is located above ground by about 1".

It may have when it was installed. Now it's grandfathered in. A new install that looked like that should not pass.

Quote:

Originally Posted by KE2KB (Post 1138644)
Is there a special type of wire I must use if I am going to bury it?
FW

Corosion resistant = copper only for burial.

Quote:

Originally Posted by KE2KB (Post 1138644)
I believe what I have coming off the antenna mast is #4 THWN, but not sure. It could be just THHN. But since it's a GC, it shouldn't need any insulation in the first place, correct?
FW

Correct. Stranded or solid, insulated, covered or bare. It would be a special kind of harda$$ that flunked you because there wasn't a W in the GEC's insulation letter code or sunlight resistant in it's specs. Still, it wouldn't look nice to see it cracking and peeling.

KE2KB 03-18-2013 09:19 PM

Quote:

Originally Posted by Glennsparky (Post 1139895)
It may have when it was installed. Now it's grandfathered in. A new install that looked like that should not pass.



Corosion resistant = copper only for burial.



Correct. Stranded or solid, insulated, covered or bare. It would be a special kind of harda$$ that flunked you because there wasn't a W in the GEC's insulation letter code or sunlight resistant in it's specs. Still, it wouldn't look nice to see it cracking and peeling.

Interesting. I can use bare copper wire, but if it is insulated, it needs to be THWN. I guess I can take my chances, and if it fails, then replace it.
I will first check the wire. It should be labeled as such.

Will I get knocked down because I have a split bolt connecting the GEC from the second GE to the GEC on the first GE?
It's the only way I can see adding the 2nd GE, unless I am going to run a new GC from the panel through the first GE (acorn nut) to the second GE as one continuous GEC. I know that code says it has to be continuous, but I believe someone here told me that continuous only to the primary GE.

What if I should decide against the second GE alltogether, and just leave the #4 wire from the primary GE to the antenna mast?
Is that still code, or do I really need to install the second GE directly beneath the antenna?

FW


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