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Dear Mr. Electrician: My neighbor was blown out of her chair when lightning hit her TV. How can I prevent that from happening to me? Answer: Basically everything needs to be properly grounded and bonded in such a manner as to provide a good direct path for lightning to flow to the earth. The photos below depict an actual job of mine correcting the grounding for a 1940's single family detached house. Article 250 in the National Electrical Code concerns grounding and bonding. Some relevant sections are: 250.8, 250.52, 250.90, 250.94, 250.104. Also read article 800.100 on grounding communication circuits and 820.100 which concerns the grounding of cable TV systems. NOTE: Text links below go to applicable products on Amazon. Grounding and Bonding for Power, Cable TV, and Telephone Water Heater Bonding For more information on steps that can be taken to improve lightning protection, please read NFPA 780. You might be interested in reading some of my other posts on grounding and bonding.
Dear Mr. Electrician: I recently hired an electrician to fix something in my very old house. He told me that the electrical service to my house did not have a good grounding electrode system and gave me a ball park price to fix it up. Why do I need this and what is involved with fixing or installing a grounding electrode system? Answer: The primary function of the grounding electrode system is voltage stabilization and lightning protection. The grounding electrode system consists of a wire or two that originate on the grounding terminal in your main electrical panel or disconnect switch. From there the wire(s) will connect to the home's water pipes and to one or more grounding electrodes. The grounding electrodes can be ground rods, concrete encased rebar, copper plates, copper wire in the footings, concrete embedded steel or other means that provide an approved electrical path to earth. NOTE: Text links below go to products on Amazon. Components of The Grounding Electrode System The main grounding electrode connection for many houses is at the metal water pipe at the point where it enters the home before the water meter. Look at this area and you should see a copper or aluminum wire; bare, insulated, metal armor jacketed, enclosed in conduit, or taped green. It should be connected to the water pipe using an approved ground clamp usually of bronze construction. The connection should be tight and free of corrosion. If the ground clamp and wire appear corroded or feels loose you should remedy this right away. A new ground clamp costs only a few dollars and can be purchased at any electrical supply company and at many home improvement stores. You will also need some emery cloth or sandpaper to clean the pipe. A good precaution when doing this would be to shut off the main circuit breaker or pull the main fuse in your electrical panel. It is possible that a tiny amount of current may be traveling over your grounding conductor. I also suggest wearing gloves and avoid touching the bare wire and the water pipe at the same time. If your home gets its water supply from a private well or through a plastic pipe, your primary ground connection should be a ground rod or two. In many cases the ground rod(s) are completely buried and therefore are not easy to inspect. According to published data, a copper plated ground rod can have a life expectancy beyond 40 years. However when working on customers homes I have discovered, loose ground rod clamps, incorrectly installed ground rod clamps, cut grounding electrode conductors, ground rods that have been damaged from landscaping and construction excavation, and short galvanized pipes driven in the earth instead of an approved ground rod. Something to consider at this time is upgrading your grounding electrode system to the latest "National Electrical Code" requirements. The current code requires that new installations have at least one supplementary ground rod installed and to also have all interior metal piping connected...