[Iris7]

I know a little about this stuff, but a long way from the "special expertise" level.

The real question as I see it is why the cascade failure? Obvously when that western Ohio line went down causing the reversal of flow with Michigan the line to Michigan should have tripped. Ohio was trying to keep power to the Cleveland area too long. Lots and lots of protection relays never tripped. Maybe hundreds. Very odd. Makes one suspect the grid operators have been setting them higher so they won't trip, and then crossing the fingers. Finally didn't work.

[Cicero]

It's possible. When we lived in Connecticut about 15 years ago, we used to have a power outage every single time there was a thunderstorm in the area. Someone in the know told me a few years after it happened that CLP had installed faulty lightning arrestors on the lines, that they knew they were faulty, but that they didn't want to pay to install new ones. After about 15 blackouts, they quietly changed the arrestors without ever telling customers what the problem was.

I'm sure competition and badly managed partial deregulation has persuaded a lot of companies to cut corners, and it's common knowledge that the carriers are not keen on developing or upgrading their networks when the authorities are forcing them to carry power for other people over their lines and when any change requires regulatory and environmental approvals.