Why One Big Storm Can Make a Utility Look Unreliable

What a major event day is

Under the IEEE 1366 standard, a major event day is a day when outage minutes are far above a utility's normal daily level - typically a hurricane, ice storm, derecho or wildfire shutoff. A few such days can account for most of a year's total outage time.

Why this site keeps them in

Utilities often prefer to quote reliability excluding those days, which shows how well the system runs in normal weather. But a generator is bought for exactly those days. So every figure here includes them: the number is what an average customer actually went through that year.

How to read a single bad year

Because storms are irregular, one year can be unusually good or bad for a given utility. If your utility's figure looks far worse than you remember, a single storm is the likely reason - and it is still useful, since it shows how long this grid takes to recover when something big does hit. The outage-length guide explains why that recovery time is the number that decides between battery and standby power.

Where to go next

See the range across large utilities: Great Lakes Energy Coop, MI, Evergy Missouri West, MO, Nashville Electric Service, TN.

How OutageRiskCheck Reads Your Utility's Outage Record · Battery, Portable or Standby Generator? It Depends on How Long Your Outages Last