Lots of comments about lightning, but I believe you are referring to a "ground loop" where the ground/neutral at one site is offset from that of a different sit

Lots of comments about lightning, but I believe you are referring to a "ground loop" where the ground/neutral at one site is offset from that of a different site tens or hundreds of meters away. This is why all commonly used RJ-45 Ethernet connections use differential signalling and have the tx/rx pairs isolated by transformers. (Note that PoE Ethernet can still create similar problems if one is not careful.) Here's a relevant news article about a lawsuit related to this phenomenon: https://easyreadernews.com/edison-stray-voltage/ https://easyreadernews.com/edison-stray-voltage/ https://www.dailybreeze.com/2013/03/19/redondo-beach-woman-awarded-4-million-in-edison-lawsuit-over-stray-electricity/ https://www.dailybreeze.com/2013/03/19/redondo-beach-woman-a... https://www.nydailynews.com/news/national/woman-wins-4m-verdict-stray-electricity-article-1.1294855 https://www.nydailynews.com/news/national/woman-wins-4m-verd...