Explore grid reliability
Use the explorer below to move between the two standard reliability metrics — SAIDI (the average minutes of interruption per customer per year) and SAIFI (the average number of interruptions per year) — and to choose whether to include major event days such as hurricanes and wildfires, exclude them, or view major events on their own.
The individual charts further down this page break out each of these views in more detail.
Outage frequency, excluding major events
Grid outages can happen for a number of reasons: equipment failures and planned maintenance, or severe weather events such as hurricanes and wildfires. First, we will look at the frequency of outages, excluding these severe (or major) event days. This gives a cleaner overview of the day-to-day reliability of these systems.
Reliability is measured using the System Average Interruption Frequency Index (SAIFI), which counts the number of outages per customer per year. A SAIFI of 1 means that, on average, each customer experiences one outage per year. These numbers are often not integers, because they are averages across all customers in a state. You can see estimates for each state in the map below.
Clicking on any state will show the outage frequency over time. You can also use the other chart tabs to compare these figures across states.
Outage frequency, including major events
This chart shows the same data — the SAIFI measure of outage frequency — but including major event days. These are days when disruption is caused by extreme weather events, such as hurricanes, wildfires, or ice storms.
This metric captures the real number of outages that customers experience, but is more volatile and makes it harder to see underlying trends in day-to-day reliability.
Outage frequency: with and without major events
This chart allows you to compare the outage frequency with and without major events included (the previous two charts). This shows how much an impact severe events have on the overall outages that customers experience.
You can use the dropdown to select a state to compare its two series.
Outage duration, excluding major events
The previous charts focused on the frequency of outages. This chart focuses on their duration.
Outage duration is measured using the System Average Interruption Duration Index (SAIDI), which counts the total number of minutes of outages per customer per year. A SAIDI of 60 means that, on average, each customer experiences one hour of outage time per year. These numbers are often not integers, because they are averages across all customers in a state.
You can see SAIDI estimates, without major events included for each state in the map below. Clicking on a state will show its change in duration over time.
Outage duration, including major events
This chart shows the same outage duration data, measured using SAIDI, but it includes major event days. These are days when disruption is caused by extreme weather events, such as hurricanes, wildfires, or ice storms.
Outage duration: with and without major events
This chart allows you to compare the average outage duration with and without major events included (the previous two charts). This shows how much an impact severe events have on the overall outage duration that customers experience.
You can use the dropdown to select a state to compare its two series.
Outage duration by utility type
How does grid reliability vary by utility type? This chart shows the average outage duration (SAIDI) for three different types of utilities: investor-owned, municipal, and cooperative.
This data is only shown at the national level, as many states only have one or two utilities per type. In the next section, though, you can explore the data for individual utilities within states.
Outage duration by individual utility
What about the duration of outages by individual utilities? You can explore the average outage duration (SAIDI) for each utility by selecting a state, then a utility within that state, from the dropdown menus in the chart below.
The data availability for this chart is more limited than the previous charts, so not all states and utilities are available.