This warning drives home the continued need to not only protect your air gapped network from digital threats, but also to make sure you completely understand and protect your power needs required by your air gapped network:
- Your Grid
- Your Generator
- Your Backup Battery
You more than likely aren't able to completely power gap your air gapped system from the grid, but you do need to consider how to isolate as much as possible your generator(s) and your backup battery(s). These capabilities will more than likely have industrial control systems (i.e. Internet of Things) that need to be protected from external threats.
If you have any best practices then please let us know by leaving a comment.