Glossary
Last reviewed
Each term has one meaning on this site. The first text is a plain explanation. The quotation is EIA's own definition, with a link to the EIA page.
- Average price
The money that a utility got from a group of customers, divided by the electricity that it sold to them. It is not the rate on a rate schedule.
EIA's definition:
Average price of electricity to ultimate consumers represents the cost per unit of electricity sold and is calculated by dividing electric revenue from ultimate consumers by the corresponding sales of electricity.
EIA, Electric Power Monthly, Technical notes (March 2024)- Cents per kilowatt-hour (kWh)
The unit of each price on this site. One kilowatt-hour is the energy that a 1,000-watt appliance uses in one hour.
EIA's definition:
A measure of electricity defined as a unit of work or energy, measured as 1 kilowatt (1,000watts) of power expended for 1 hour. One kWh is equivalent to 3,412 Btu.
EIA Glossary, "Kilowatthour (kWh)"- Average monthly bill
The residential revenue of a year, divided by the number of residential customers and by 12 months. For one month, it is the revenue of the month divided by the customers.
EIA's glossary has no entry for this term. The explanation is this site's own.
- Rate schedule
The list of rates and charges from which a utility makes a bill. The utility or the state utility commission publishes it. This site does not have rate schedules.
EIA's definition:
The rates, charges, and provisions under which service is supplied to the designated class of customers.
EIA Glossary, "Rate schedule (electric)"- Residential
Homes and apartments. On EIA's forms, a utility puts each customer in one of four sectors, and the residential sector is one of them.
EIA's definition:
An energy-consuming sector that consists of living quarters for private households. Common uses of energy associated with this sector include space heating, water heating, air conditioning, lighting, refrigeration, cooking, and running a variety of other appliances. The residential sector excludes institutional living quarters. Note: Various EIA programs differ in sectoral coverage.
EIA Glossary, "Residential sector"- Customer
One account or one meter, not one person. The count for a year is the average of the 12 counts at the end of each month.
EIA's definition:
For number of customers, enter the average of the 12 close-of-month customer accounts.
EIA, Form EIA-861 instructions- Bundled service
One company sells the electricity, delivers it and sends the bill. The average prices on this site are for bundled service.
EIA's definition:
A means of operation whereby energy, transmission, and distribution services, as well as ancillary and retail services, are provided by one entity.
EIA Glossary, "Bundled utility service (electric)"- Delivery company
A company that operates the power lines and delivers electricity, but does not sell it. On this site, the term is for the Texas companies in EIA's Delivery Companies file.
EIA's definition:
The data contain revenue, sales, and customer count by sector from utilities that deliver energy in Texas.
EIA, Form EIA-861 detailed data files, "Delivery Companies"- Retail electric provider
In the parts of Texas with retail choice, the company that sells the electricity and sends the bill. EIA's name for this type of company is retail power marketer.
EIA's definition:
Retail Power Marketer (R) or Energy Service Provider: Entities that market power to customers in restructured markets.
EIA, Form EIA-861 instructions- Service territory
The counties in which a utility has equipment to deliver electricity. A utility can serve only a part of a county on its list.
EIA's definition:
The data contain names of counties and states in which the utility has equipment to distribute electricity to ultimate customers.
EIA, Form EIA-861 detailed data files, "Service Territory"- Investor-owned utility
A utility that a private company with shareholders owns. A regulator sets its rates.
EIA's definition:
A privately-owned electric utility whose stock is publicly traded. It is rate regulated and authorized to achieve an allowed rate of return.
EIA Glossary, "Investor-owned utility (IOU)"- Cooperative
A utility that its customers own. This site also uses the full name, electric cooperative.
EIA's definition:
An electric utility legally established to be owned by and operated for the benefit of those using its service. The utility company will generate, transmit, and/or distribute supplies of electric energy to a specified area not being serviced by another utility. Such ventures are generally exempt from Federal income tax laws. Most electric cooperatives have been initially financed by the Rural Utilities Service (prior Rural Electrification Administration), U.S. Department of Agriculture.
EIA Glossary, "Cooperative electric utility"- Municipal utility
A utility that a city or a town operates for its residents.
EIA's definition:
Municipal (M): Entities that are organized under authority of state statute to provide a public service to residents of that area.
EIA, Form EIA-861 instructions- SAIDI
The minutes without power for the average customer of a utility in one year. Very short interruptions are not in the figure.
EIA's definition:
SAIDI = System Average Interruption Duration Index. It is the minutes of non-momentary electric interruptions, per year, the average customer experienced.
EIA, Electric Power Annual with data for 2024, Table 11.1, notes (October 2025)- SAIFI
The number of interruptions for the average customer of a utility in one year. Very short interruptions are not in the figure.
EIA's definition:
SAIFI = System Average Interruption Frequency Index. It is the number of non-momentary electric interruptions, per year, the average customer experienced.
EIA, Electric Power Annual with data for 2024, Table 11.1, notes (October 2025)- Major event days
Days on which the outages of a utility are much larger than usual, for example in a large storm. A utility reports SAIDI and SAIFI with these days and without them.
EIA's definition:
For utilities using the IEEE method, a Major Event Day is any day that exceeds a daily SAIDI threshold called Tmed. Tmed is a duration statistic calculated from daily SAIDI values from the past five years. For utilities not using IEEE methods, Major Events are self-determined by the reporting utility.
EIA, Electric Power Annual with data for 2024, Table 11.1, notes (October 2025)- Early release
The first version of the Form EIA-861 files for a year. EIA publishes it in the summer, before it completes its edits. This site shows it on the page of a utility only.
EIA's definition:
The data has not been fully edited and is inappropriate for aggregation, such as to state or national totals.
EIA, Form EIA-861 detailed data files, note in each file of the early release- Final annual file
The Form EIA-861 files for a year after EIA completes its edits. EIA publishes them in the autumn of the next year. Each average and each median on this site uses a final annual file.
EIA's glossary has no entry for this term. The explanation is this site's own.
The site copied EIA's definitions on . A quotation keeps EIA's spelling, for example "kilowatthour".