The North American Electric Reliability Council released a preliminary disturbance report on Friday, listing a partial sequence of events before and during the large blackout in the Northeastern United States and Canada that occurred last week. The information is based on Reliability Coordinator information available to NERC. It is not clear if these events caused the blackout or if they were consequences of other events. NERC is establishing teams to study and will coordinate with FERC, the Department of Energy, the industry and others.

Approximate times — Eastern Standard Time — MISO report only

14:06 Chamberlain – Harding 345 kV line tripped – cause not reported
14:32 Hanna – Juniper 345 kV line sagged and tripped
14:41 Star – S. Canton 345 kV line tripped
14:46 Tidd – Canton Ctrl 345 kV line tripped
15:06 Sammis – Star 345 kV line tripped and reclosed
(The preceding lines are located in the vicinity of Cleveland, Ohio.)
15:08 Power swings noted in Canada and Eastern United States
15:10 Campbell #3 tripped??
15:10 Hampton – Thetford 345 kV line tripped
15:10 Oneida – Majestic 345 kV line tripped
15:11 Avon Unit 9 tripped
15:11 Beaver – Davis Besse
15:11 Midway – Lemoyne – Foster 138(?) kV line tripped
15:11 Perry Unit 1 tripped
15:15 Sammis – Star 345 kV line tripped and reclosed
15:17 Fermi Nuclear tripped
15:17 – 15:21 Numerous lines in Michigan tripped

The Northeastern United States and Canada did not report significant outages prior to 15:11 EST.