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The National Electrical Code (NEC) specifies that there be two
grounding points for a residential system. That can mean either two ground rods, six feet apart, connected to the panel with a continuous loop of wire, or a single ground rod in cases where there is municipal water, and the second ground source is the water main coming in, on the road side of the meter. The gas line also needs to be grounded to the panel. In the main service panel, the grounding system is attached to the same buss as the bare neutral coming in from the transformer. If your shack is running off a sub-panel, it should be fed with four conductor cable. In this case an insulated neutral is used and the bare (or insulated, it doesn't matter in this instance) ground is connected to a separate equipment ground buss. If your shack is in a separate structure that has its own sub panel, it needs to be fed with three conductor ground, the neutral is connected to the ground bar and a ground wire from a single ground rod is connected to the same buss (similar to the setup at the main panel). It sounds confusing as written here, and it's even more confusing to read it from the NEC, but I just had this out yesterday with my local inspector while going over the fine points on a job. All that NEC stuff is important to check to make sure you're setup is electrically safe. As for station grounding, it's not usually a good idea to use the electrical system ground rods for your RF grounds. Your rig, tuner, amps, etc, should all be grounded to a single buss with the shortest possible wires, then a large chunk of wire, #6 or better, should run as directly as possible to a separate 8' ground rod. If you have a tower, you should drive at least one 8 footer at the base and ground it there. There's no limit to the number of ground rods you can have for RF grounds, they're less than $10 from a distributor and well worth the effort. I've heard of hams setting up verticals with very minimal radials, just driving several ground rods. But somewhere along the line somebody in the ham groups stated that the National Electrical Code states that there shall be one and *only one* grounding point per power drop and the neighborhood code cops and the insurance companies reportedly get stiff about it. The answer to that is that if there is more than one they must be connected. The methods differ depending on the location of services in the structures and around the property. An electrician following the NEC would have done this during the installation and (hopefully) the inspector would have signed off on it. Ground rods for RF equipment SHOULD NOT be connected in any way to the electrical system ground rods. 73 KC2PNF Jon Dayton |
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