FLASHBACK: San Jose, CA substation attack on April 16th, 2013:

"The yet-unsolved case has been shrouded in mystery. No suspects have been named... no motive identified."

Here are a few headlines:
"Sniper attack on California power grid may have been 'an insider,' DHS says"
"FBI: Attack on PG&E South Bay substation wasn't terrorism"
"Sophisticated but low-tech power grid attack baffles authorities"
"‘Military-Style’ Raid on California Power Station Spooks U.S."

The Most Terrifying Attack You Never Heard About - Metcalf Substation
https://www.youtube.com/watch?v=Q4hwFBPyS5U

The video mentioned that the perps: "“Aimed for transformer oil cooling systems”."

What happened with NC?: "The company said vandals damaged transformers, causing them to leak coolant oil, but the statement doesn’t say how."

www.newsobserver.com/news/local/article269713541.html#storylink=cpy

Think GridEX drills.