GridWatch — glossary
Plain-language definitions of the terms used across GridWatch (Community reports).
The grid
- Generation
- The stage where electricity is produced — power plants, wind and solar farms. A failure here can affect a wide region, but it is comparatively rare.
- Transmission
- The high-voltage, long-distance lines on large steel towers that carry power from generators toward cities. Damage here can darken an entire region at once.
- Distribution
- The local network — substations and the lines on neighborhood poles that bring power to homes and businesses. Most outages are distribution faults affecting a street or town.
- Substation
- A facility that steps high transmission voltage down to lower distribution voltage. A substation problem can take out power for everything it feeds.
Reading the data
- % customers out
- The share of a utility’s tracked customers in an area that are without power. The unit on GridWatch’s scale, from minimal (green) to widespread (red).
- Customer
- A single metered account — one household or business — not a person. Because households hold several people, the number of people affected is higher than the customer count.
- Estimated restoration time (ETR)
- A utility’s best estimate of when power will return. It is an estimate, not a guarantee, and can slip or be withheld until crews finish assessing damage.
- Restoration priority
- The order utilities repair the system: region-wide transmission and substation damage first, then critical facilities, then the repairs that restore the most customers, then isolated homes.
Causes & deliberate outages
- Public Safety Power Shutoff (PSPS)
- A deliberate, preemptive outage a utility triggers during extreme fire weather, cutting power so its lines cannot spark a wildfire.
- Rolling blackout
- Controlled, rotating outages a grid operator imposes when demand threatens to exceed supply, sharing the shortfall across areas to prevent an uncontrolled collapse. Also called load shedding.
- Load shedding
- Intentionally reducing electricity demand by cutting power to selected areas when supply runs short. The mechanism behind a rolling blackout.
- Demand peak
- The point of highest electricity use — often a hot afternoon when air conditioners run together. Demand near the grid’s limit can overheat and trip equipment.
Intensity scale (reports (48h))
- No reports
- 0 reports (48h)
- 1 report
- 1 reports (48h)
- A few reports
- 3 reports (48h)
- Many reports
- 10 reports (48h)
- Widespread reports
- 25 reports (48h)