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![]() "Jim Miller" Hi Jack Well I moved some stuff around in the basement and found the house ground. It actually protrudes out of the concrete floor directly below the two breaker panels. Each panel has what appears to be #4 solid copper coming down to bronze clamps on this rod. There's no ground outside at all which is why the Verizon guy chose to ground to the Thomas and Betts meter cabinet that I mentioned which is 4ftx6"x15" or so and partially buried. Here in MD they just do direct burial rather than use a conduit. The entry to the house panels from the meter box is just via heavy cable, no conduit there either. The Comcast guy just put a ground on the splitter and ran it a foot or so to the closest circuit breaker panel. So should I just drive one more rod pretty close to the box to finish the daisy chain close, then go inside and bond to the single point there? Seems crazy to take this inside... I'll have to drill a hole through the sill plate on an angle then feed the wire up from my proposed exterior ground rod, through the sill plate, then down the inside of the concrete basement wall to where the other two grounds are attached to the ground post. tnx jtm Good job scoping out what you have, Jim. It is unfortunately, non-conformant by your description. Utility service entrances are required to be single point grounded at one entry point. Bonding through basement walls will never meet that requirement, besides being difficult to accomplish. The potential between your Verizon lines and Electric lines could be huge, should the nearby utility pole, a tree in your yard, etc be struck. The phone issue may never be a problem unless...you use phone-patch equipment connected to a radio. You previously asked if it is allright to improve the AC mains ground rod (when you thought you had one outside). The answer is yes, and most as installed by the building contractor are barely sufficient for handling surge voltages that nearby lightning can send to the meter. Adding a second and third ground rod (in a "Y" formation for instance) greatly improves the protection from utility high voltage damage to your home, providing you have good surge protection installed. Sans surge protection? Don't bother with more ground rods. In your case though, you probably have an excellent grounding electrode under the house. You do realize that the finished grade outside is probably as much as 10,000v "above ground" from that under-basement electrode! Too bad Verizon didn't see fit to make their box ground at the same place. I would ask Verizon what to do, get a grounding technician to come out to your place and explain to him that you have communications equipment connected and expect a code-installation of all utilities before you can complete lightning protection systems. If he demonstrates to your satisfaction that it DOES meet code, please sketch (paint program, or photos scanned, etc) what you have and send it. I will be happy to get a telco communications engineer to comment (and it won't be Verizon). It may be that the electrical code and telco standards *do not protect you* in your individual circumstances. Meanwhile, you can make a bond between your AC panel ground rod and the station single point ground, as most of us are unfortunately situated far apart when ideally they would be next to each other. That bonding connector can be insulated wire through interior walls, utility chases, under floors, etc. Preferably use #6 wire minimum. It HAS to be much lower impedance that the home's AC outlet grounding wires, how much lower is up to your individual circumstances. I just replaced #4 copper with 13" wide 20 gage copper sheeting, because I had over 50' of separation between station ground and AC mains ground. That's an awful potential, and begs high voltage felt at the station ground from a nearby strike, to blast out the back of the radios and into the power grid. Surge protection alone cannot save you from ground potential rise, but a bond from station ground to AC ground that is much lower impedance than the house wiring will MINIMIZE the effect on your equipment, and all home appliances. Richard Harrison in this group had a much better solution for my type of problem, and that was to route ALL antenna feedlines to the AC Mains ground point BEFORE entering the home. Unfortunately that would have been a design issue when I started my station, and so I used the next best alternative, the best bonding possible between the two. I suggest proceeding with that effort and shield grounding, etc, until an expert from the telco and/or electric company can visit and review your situation. Best regards, Jack |
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