> How about aircraft or shells or covert actors spray some "thing" that shorts out electrical insulators 1000x more often than normal.
Dropping anti-radar chaff strips is a very good lo-tech way of shorting transformers and power lines. I can't find a link, but IIRC the USAF discovered this accidentally when training missions led to power outages in nearby towns.
The US has a dedicated submunition for this mission called the BLU-114/B. It has been highly effective in past uses, though I imagine cleanup after the conclusion of hostilities was a serious pain. There's been research into even smaller conductors that would get inside fan-cooled equipment, though a.) one might imagine potentially negative health impacts on persons exposed to these materials, and b.) it might be difficult to occupy an area previously hit with these types of munitions given the proliferation of fan-cooled equipment in the military.
Dropping anti-radar chaff strips is a very good lo-tech way of shorting transformers and power lines. I can't find a link, but IIRC the USAF discovered this accidentally when training missions led to power outages in nearby towns.