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I need to ground an antenna strapped to my chimney, which requires hammering in a new ground rod.

However, the entire side of my house is paved, meaning I can't dig it up to find the foundation footing; I'll need to drill a hole to drive in the rod.

How far should the ground rod be from the side of the house so it doesn't hit the footing? (This is especially a concern because it'll be right next to the chimney stack.)

Also, please keep any answers to code (NFPA 70), as I need it to be able to pass inspection. If it is of any relevance, the house was built in 1942.

  • Can't vouch for code, but the ground for my solar system was driven about a foot out from the brick-over-fieldstone foundation, with conduit run from the exterior switch box to it so the actual wire had some protection from misplaced shovels and such. – keshlam Jul 27 '14 at 5:19
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There is no minimum or maximum distance from a foundation, footing, panel or otherwise.

It is best to keep it as close as possible, but nothing dictates this by code. The main thing you want to avoid is getting it a few feed down then hitting the footing. This is a PIA.

Here are the relevant code sections with regard to spacing. Taken form the 2001 NEC.

III. Grounding Electrode System and Grounding Electrode Conductor

250.50 Grounding Electrode System

All grounding electrodes as described in 250.52(A)(1) through (A)(7) that are present at each building or structure served shall be bonded together to form the grounding electrode system. Where none of these grounding electrodes exist, one or more of the grounding electrodes specified in 250.52(A)(4) through (A)(8) shall be installed and used.

250.53 Grounding Electrode System Installation

(B) Electrode Spacing.

Where more than one of the electrodes of the type specified in 250.52(A)(5) or (A)(7) are used, each electrode of one grounding system (including that used for strike termination devices) shall not be less than 1.83 m (6 ft) from any other electrode of another grounding system. Two or more grounding electrodes that are bonded together shall be considered a single grounding electrode system.

(G) Rod and Pipe Electrodes.

The electrode shall be installed such that at least 2.44 m (8 ft) of length is in contact with the soil. It shall be driven to a depth of not less than 2.44 m (8 ft) except that, where rock bottom is encountered, the electrode shall be driven at an oblique angle not to exceed 45 degrees from the vertical or, where rock bottom is encountered at an angle up to 45 degrees, the electrode shall be permitted to be buried in a trench that is at least 750 mm (30 in.) deep. The upper end of the electrode shall be flush with or below ground level unless the aboveground end and the grounding electrode conductor attachment are protected against physical damage as specified in 250.10.

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I don't think there is any specification for minimum distance from the structure. It just has to be driven in a full 8 feet. Probably you will want to avoid driving it through the footing, though I suppose you could if you pre-drilled it. In your case, maybe you want to run the ground wire around the corner to a more convenient place to install the ground rods. I do recall there is a maximum distance they can be located, but it is pretty generous and usually trumped by "as close as practical" language in the code.

  • I would have made the suggestion to run it around the corner if you hadn't. I like that option. I wouldn't want his thing sticking out if my pavement, anyway. – Craig Sep 25 '16 at 6:03
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The grounding electrode conductors can be used to allow installation of the grounding electrode sufficiently far from the structure to avoid the footings. There is little point in speculating in regard to the size and configuration of existing foundations. However an reasonable estimate might be made using excavations on one or more other areas of the structure.

It is possible that properly installed grounding electrode conductors would allow the electrode to be installed in a location with fewer unusual conditions (depending of course on the site configuration).

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I know this is an old post, but... the ground rod should not come in contact with the concrete footing/foundation of the home, which typically protrudes a foot from the house. Because of this, it is highly recommended the closest ground rod not be any closer than two feet from the home. The second rod should be right feet from the first.

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    Can you expand on the justification behind these recommendations? – ThreePhaseEel Nov 18 '17 at 23:35
  • Hello, and welcome to Stack Exchange. When your recommendation includes an unfamiliar requirement, you should include some back-up material saying why this is so. – Daniel Griscom Nov 19 '17 at 14:40

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