The 5 foot ground rod and its use in the National Electric Code (2018)
As we are talking about grounding...<p>I think the greatest problem that troubles me personally is that the single-point grounding required by lightning protection is <i>almost never</i> implemented properly in the vast majority of installations.<p>I realized the existence of this problem when I wanted to install a mesh network in a school campus, so I started reading documents about lightning protections, amateur radio publications have good resources on it, and all of them indicate a correct installation should eventually bound all grounds, including mains ground, telecommunication ground and lightning protection ground at a single-point via low-impedance connections (even if they have their own ground rods), also, all metallic objects and structures, such as gas pipes, fire escapes, etc, should be bounded to ground as well. This is to prevent a voltage gradient developing between different grounding points in case of a lightning strike, and it&#x27;s usually required or implied in electrical or building code.<p>However, who ever obey this rule in practice? I&#x27;ve seen various installations of outdoor&#x2F;rooftop Wi-Fi networks, and all the lightning protection they have is a gas discharge tube and a ground connection of unknown quality, I don&#x27;t think the installation is legal. Also, many buildings were in compliance of the code when they were built, but even adding an extra metal frame or a cable-TV box will invalidate the entire lightning protection, at least from a technical or legal perspective.<p>I guess the reason behind the non-compliance is that the likelihood of a lightning strike is already low, even if it does strike, it&#x27;s possible that even a non-compliant lightning protection system can work to an extent. And if it doesn&#x27;t work, most people would just accept the damage. As a result, it&#x27;s a concern for radio hobbyist only, whose antenna increases the likelihood significantly.<p>But I was still shocked when I first understood the fact that most (low-rise) buildings don&#x27;t have a technically sound lightning protection system and bet the safety of the building on luck. And its practical consequence is: if you want to put a rooftop antenna for amateur radio, with good lightning safety and in compliance with the code, in many cases, the answer is you can&#x27;t - the building often doesn&#x27;t even have a technically sound lightning protection system to begin with. I read many hardcore radio amateurs redo the entire electrical wiring at their homes to the proper standards.<p>High-rise buildings are much better, lightning protection is serious business, but you are not usually allowed to put a mesh network antenna on top of them. But if you are allowed, I&#x27;ve heard that some people even got a chance to have a friendly conversation with the civil engineer who&#x27;s in charge of the building&#x27;s lightning protection system and work out a solution together.