When planning the installation of the weather vane, the wind vane, the question arises: should the weather vane be grounded? I have been designing grounding systems for the petrochemical industry for almost 50 years and have designed some grounding and lightning protection systems during that time. A construction site, whether it’s a house, a garage, a barn, or whatever, can have multiple grounding systems. A primary system is the electrical safety ground system. This is the wire that connects a ground electrode, sometimes a water pipe, to the breaker panel and goes to all receptacles. The electrical safety ground ensures a good ground connection that is required to trip the breaker in the event of a short circuit. If you have a computer system, you may need a separate isolated ground system to prevent electronic noise through the ground system. What we want to talk about now is the lightning protection system and its weather vane. An effective lightning protection system will have a series of lightning rods, properly spaced at high points of the structure. The lightning rods will be connected to each other and to the ground rods with copper or aluminum conductors. The lightning protection system helps drain negative ions in the air as it moves through the lightning rods, lessening the chance of a direct lightning strike. Negative ions accumulate as air moves across the land. This is similar to static electricity, like sliding your feet on the carpet and then touching something and drawing an arc, and as you know lightning is more powerful.
In conclusion, it is my opinion that your wind vane should Never connect to your electrical safety ground or to the isolated ground of your computer. If you have a lightning protection system installed on your structure, you must connect your wind vane to your system with an appropriate conductor. If you don’t have a lightning protection system installed, then a ground connection to your weather vane is not needed and can even damage it during a storm.