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I've thoroughly researched the grounding requirements of such towers and equipment, but there are still some details I'm not quite sure on. Tower requirement for grounding electrode as per NEC, one for each leg of tower and of course grounding blocks for coax signal cable and current isolation for rotator control wires, all bonded to grounding electrode system.

All reliable sources state the tower grounding electrodes are to be bonded to main structure grounding electrode. I installed a single 5/8" copper-clad steel 8' ground rod some years ago upon discovering that this structure was not grounded AT ALL. (water system is cistern and previous owners had only bonded electrical system to interior copper supply lines! - no earth contact!)

I have been making significant improvements to this structure (my home) for the last 15yrs. and one of the latest built a sizable addition and installed a 100 amp sub-panel. Not quite sure how I accomplished it, since I only this past week did enough reading to understand the why's and wherefores of separating the neutral wires from the grounds in the sub-panel and making sure they are not bonded, and also the proper feeder circuit conductors (3-wire w/gd or '4-wire') all of which has been done correctly. Not long after energizing this sub-panel I did drive a separate and similar ground rod external and near the location of this new sub-panel. During subsequent exterior construction the grounding electrode conductor was disconnected from the grounding electrode and never re-connected.

Bear with me, I'm getting to my question. The TV antenna tower will be in the near vicinity of where the secondary (now disconnected) ground rod is, at the rear of the original structure and on the opposite side where the main grounding electrode is located (near the SEP, a 200 amp distribution panel.)

Would it be electrically acceptable to: (using one continuous #4 copper conductor) reconnect the sub-panel ground to the disconnected grounding electrode then to the new grounding electrodes for the tower and then through to the original grounding electrode at the front of the house? I also intend to drive another 5/8"x8' copper-clad steel grounding electrode at the front of the house and include that in the uninterrupted grounding electrode conductor. My research indicates that good practice now recommends the installation of 2 grounding electrodes to obtain the low impedance expected of the grounding system.

Another way of stating my concern is: Is it necessary or even desirable to have that "auxiliary" ground at the sub-panel? I believe I understand the purpose of bonding all the systems together at one point to prevent a ground loop or the possibility of inducing a current across circuits within the system because of different voltage potential within the system.

I'm no expert but have noticed many contradictory statements and opinions concerning proper grounding of residential structures.

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  • What sort of system will you be using for lightning strike protection?
    – Armand
    Apr 26, 2023 at 20:40
  • I presume you mean for the tower(?) As stated, a 5/8"x8' copper-clad grounding electrode bonded to each tower leg (3 total); a grounding block installed in-line of the RG6 coax signal cable with F connectors and a surge dissipation unit for the control wires to the antenna rotator made by DX Engineering. Those lead-ins bonded to the tower leg grounding electrode system.
    – Vince L
    Apr 26, 2023 at 20:56
  • Regarding the piece about a single continuous #4 copper looping everything together: that's unnecessarily difficult. While it's true that the conductor running to a particular grounding electrode must be continuous/unbroken (or irreversibly spliced), separate electrodes may be connected back to the grounding point each with their own separate continuous/unbroken conductors. Daisy-chain some of them as you described if it's convenient, but don't feel like you have to weave 200 ft of #4 copper through the property to connect all on one length of wire!
    – Greg Hill
    Apr 26, 2023 at 21:33
  • Greg, thanks for your reply. In this case - the physical arrangement/placement of all these components- does make it convenient to do it this way. I guess my question revolves around whether or not it is necessary or desirable to have the sub-panel ground as part of this "circuit" (as opposed to just defaulting to the ground (green conductor) in the feeder line.)
    – Vince L
    Apr 26, 2023 at 22:11

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You're best off keeping the equipment grounding conductor for the subpanel separate from the grounding electrode conductor system

In order to prevent objectionable (and Code-violating) 60Hz current from the grounding electrode system (usual culprit is a neighbor with a dodgy neutral) from getting onto the equipment grounding system, you're best off not tying the subpanel grounding bus to the grounding electrode system directly. This prevents a literal ground loop and its associated common-impedance coupling, as well as ensuring current is not continuously flowing on the normally non-energized equipment safety ground in the subpanel's feeder. (See NEC 250.121 and NEC 250.6(A) for details.)

As to the tower grounding plan, though, that part of it is alright. NEC 810.21(F)(2) requires the tower electrodes be tied to the power grounding electrode system to avoid damaging potential differences, and having them along the path is reasonable, thanks to NEC 810.21(I).

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