Removing a ground rod

[transferguy]

Posted By: Mr T

I am getting ready to drive a ground rod for my house (currently none).

This area has very shallow bedrock. The water/sewer lines are only a foot - foot and a half under the street because of it. I have trenched in my back yard and didnt hit anything 2 feet down. I am going to attempt to drive a ground rod near the front of my house (near that street with the shallow lines). I am thinking of driving it at a 45degree angle. If I hit rock when it's mostly driven in,how hard will it be to pull the rod back out so I can try elsewhere (or just bury it)?

[transferguy]

posted by: suemarkp

I think you'll have a hard time getting it out, but it is proportional to hard hard it went in. If it goes in easy and then just stops, you may be able to get it back out. But I don't know of a reverse driver for rods. People just want to pound them in, not remove them. Perhaps a vise grip you're not afraid to whack with a hammer. Rotate it all the way around, whack, repeat. Cut it off if you have to and try another location.

Code permits driving it at an angle if you hit bedrock.

Mark
Kent, WA

[transferguy]

posted by: chris

We use a lot of ground plates here. You dig a hole 3 feet deep and throw it in. Fill the hole.

[transferguy]

posted by: Mr T

I was thinking of just trying my luck and seeing if I hit rock. I would want to be able to try it in another area if I dont destroy it in my effort. Ive thought about the vise grip idea.. It wont be the first time they've gotten to know my hammers.

Are ground plates generally accepted everywhere (in the US?)? I have heard of them, but not heard of them being used around here.

Getting down 36" may be a challenge unless I get lucky. How close can these be to the foundation?

[transferguy]

posted by: suemarkp

Plates are allowed in the NEC (250.52(A)(7): Plate Electrodes. Each plate electrode shall expose not less than 0.186 m2 (2 ft2) of surface to exterior soil. Electrodes
of bare or conductively coated iron or steel plates shall be at least 6.4 mm (1⁄4 in.) in thickness. Solid, uncoated electrodes of nonferrous metal shall be at least
1.5 mm (0.06 in.) in thickness.

Plate electrodes must be at least 30" down. If you hit a solid rock layer with a rod, you are also permitted to bury it horizontally as long as that trench is 30" down (I think a plate would be less digging than 8' long trench).

Plates are treated like rods in that you need two if you can't prove 25 ohms, and space them at least 6' apart.

Mark
Kent, WA

[transferguy]

posted by: navyguy

We bury ground-rods horizontally or use plates all time in our area due to bedrock just below the surface. If they are less than the minimum depth required, then they are covered with concrete. In this area we tend to use the copper water line from the street as a system ground which is also acceptable in our CEC. Not sure if you have similar codes in the NEC.

Cheers

John

[transferguy]

posted by: suemarkp

Most houses being built in the US today have plastic from the street. Older ones that are copper, and come into the house as metal, must use that as a ground electrode. However, it can't be the only electrode -- a water pipe must be supplemented with at least one rod, and a 2'd one if you can't prove the rod is 25 ohms or less. I think they want to ensure a good ground in case your water pipe from the street gets replaced with plastic.

Mark
Kent, WA

[transferguy]

posted by: Mr T

I spoke with a neighbor and they had no trouble pounding a straight rod in when their house was built a few years ago. Their house is a good distance away from mine, so it may not mean anything. I am going to try to pound something smaller in a few feet this weekend to see what I hit.

If I would go with a ground plate, do I need to do anything special with the wire going to it? (will be 4ga solid copper)

I have copper coming out of the ground for my water line. I am very close if not just shy of 10 feet of underground copper between where it goes into the ground and the underground meter. In addition, this point is about 30 feet from my service entrance. I am planning on replacing most of my piping with PEX soon, so picking a closer pipe isnt really an option. Is either of these a issue for it being a secondary ground point? I thought I read somewhere that there had to be 10' of metal.

[transferguy]

posted by: chrisb

You use the same cable/wire for a plate as you do for a rod.

[transferguy]

posted by: suemarkp

All the pipe length changes is whether you have to use the pipe as an electrode or not. If it is 10' or longer you do. Kind of hard for an inspector to measure unless you dig it up, but he may "know" how the houses were built and have a length in his head which you'll need to disprove if he disagrees. So best to just treat it as an electrode. If you will have no pipe inside that is metal, then you don't need to bond the interior piping. If you do, then I'd run your #4 copper from the panel to the water pipe, and it must connect within 5' of where that pipe enters the house if the water pipe is also a ground electrode. If nothing metal inside, then you can ground the buried pipe outside (just bury a #4 in the dirt along the foundation between the service entrance and the pipe). You'll need a ground clamp for the pipe that is rated for direct bury in this case (they are bronze and have a "direct bury" label on them). Depth for the wire is not specified in the code. Most inspectors will accept 12".

Mark
Kent, WA