I. – Investigation: Used to designate "Order Instituting Investigation (OII)" when placed before the Commission assigned proceeding number, such as I.01-02-003.

IBEW – International Brotherhood of Electrical Workers: Represents approximately 750,000 members who work in a wide variety of fields, including utilities, construction, telecommunications, broadcasting, manufacturing, railroads and government.

ICC – Interstate Commerce Commission: The federal agency that regulates interstate trucking companies, bus lines, and railroads.

IECs – Interexchange Carriers: Telephone companies that provide long distance service or sell telephone lines. MCI, Sprint, and AT&T are examples of these carriers.

IEP – Independent Energy Producers Association: California 's oldest and leading trade association representing the interests of developers and operators of independent energy facilities and independent power marketers. Independent energy producers include producers of renewable products derived from biomass, geothermal, small hydro, solar, and wind; producers of highly efficient cogeneration; and owners/operators of gas-fired merchant facilities.

IER – Incremental Energy Rate: A measure of the efficiency of an electric utility's power production.

ILECs – Incumbent Local Exchange Carriers: The traditional wireline telephone service providers within defined geographic areas. Prior to 1996, ILECs operated as monopolies having the exclusive right and responsibility for providing local and local toll telephone service. ILECs include regional Bell operating companies such as Pacific Bell / SBC and non-Bell affiliated companies such as Roseville Telephone Company, both in California .

Impact fee: A fee charged to developers to cover part or all of the costs of providing service.

Incidental Recharge: Water incidentally added to a groundwater aquifer due to irrigation or discharge of waste.

Incision: Extensive degradation or down-cutting of a stream or river bed.

Industrial: This utility customer class is generally defined as manufacturing, construction, mining agriculture, fishing and forestry establishments Standard Industrial Classification (SIC) codes 01-39. The utility may classify industrial service using the SIC codes, or based on demand or annual usage exceeding some specified limit. The limit may be set by the utility based on the rate schedule of the utility.

Infiltration: The process of water entering the soil surface.

Inside Wiring: That portion of the telephone wire and jacks inside a residence or business for which the customer is responsible for repairs and maintenance.

Instream Uses: The beneficial uses of water within a river or stream, such as providing habitat for aquatic life, sport fishing, river rafting or scenic beauty.

INTELSAT – International Telecommunications Satellite Organization: Formed under a multilateral agreement, it is the organization which owns, maintains, and operates the global satellite system used by over 100 participating countries throughout the world.

Inter-Basin Transfer: Water transfers from entities outside a watershed to entities within a watershed.

Intercept: To stop a telephone call directed to an improper telephone number, and redirect that call to an operator or a recording.

Interconnect Company: A non-regulated, non-utility firm providing terminal communications equipment and inside wiring to the public.

InterLATA: Long distance telephone service between local access and transport area and international telephone service

Internal Combustion Plant: A plant in which the prime mover is an internal combustion engine. An internal combustion engine has one or more cylinders in which the process of combustion takes place, converting energy released from the rapid burning of a fuel-air mixture into mechanical energy. Diesel or gas-fired engines are the principal types used in electric plants. The plant is usually operated during periods of high demand for electricity.

Internet: An electronic communications network connecting computer networks and organizational computer facilities throughout the world.

Interested Party: An individual or group appearing in a formal proceeding without declaring in advance a position for or against a proposal in question.

Interruptible Capacity: Interstate pipeline, backbone transmission or storage capacity, which may be available from time to time, but cannot be assured under all operating conditions.

Interruptible Gas: Gas sold to customers with a provision that permits curtailment or cessation of service at the discretion of the distributing company under certain circumstances, as specified in the service contract.

Interruptible Load: Refers to program activities that, in accordance with contractual arrangements, can interrupt consumer load at times of seasonal peak load by direct control of the utility system operator or by action of the consumer at the direct request of the system operator. It usually involves commercial and industrial consumers. In some instances the load reduction may be affected by direct action of the system operator (remote tripping) after notice to the consumer in accordance with contractual provisions. For example, loads that can be interrupted to fulfill planning or operation reserve requirements should be reported as Interruptible Load. Interruptible Load as defined here excludes Direct Load Control and Other Load Management. (Interruptible Load, as reported here, is synonymous with Interruptible Demand reported to the North American Electric Reliability Council on the voluntary Form EIA-411, "Coordinated Regional Bulk Power Supply Program Report," with the exception that annual peakload effects are reported on the Form EIA-861 and seasonal (i.e., summer and winter) peakload effects are reported on the EIA-411).

IntraLATA: Telephone service within a local access and transport area (LATA)

Intrastate Traffic: Trade whose origin, destination, and entire transportation route lies within the same state.

Investigation and Suspension: A petition to suspend and investigate tariffs, schedules, contracts, or terms and conditions of service that are claimed to be unlawful.

IOUs – Investor-Owned Utilities: Publicly traded corporations that provide electric service for its customers and earns a profit for its shareholders. Pacific Gas and Electric, Southern California Edison and San Diego Gas and Electric are IOUs.

IP Telephony: Evolving, packet-based systems that can more efficiently move voice and data traffic simultaneously via the Internet. IP telephony technology represents a lower cost alternative to circuit-switches for providing (mostly residential) local service.

IPP – Independent Power Producer: A non-utility power producer that operates within the franchised service territory of a host utility and sells electricity at market rates.

IRC – International Record Carrier: A common carrier engaged in providing overseas telecommunications service such as telex and voice data service.

IRD – Implementation Rate Design: The PUC investigation into allowing long distance companies to compete with local phone companies in carrying local toll calls, and how rates for local phone services need to be rebalanced to ensure revenue neutrality.

Irrigation District: A political entity responsible for securing and distributing water supplies for agricultural and municipal customers. The PUC does not have regulatory oversight of irrigation districts.

ISDN – Integrated Services Digital Network: Considered to be the basis for a "universal network" that can support almost any type of communications device or service. ISDN is a network that provides end-to-end digital connection for simultaneous transmission of voice and/or data over multiple multiplexed communication channels.

ISO – Independent System Operator: An independent, Federally regulated entity that coordinates regional transmission in a non-discriminatory manner and ensures the safety and reliability of the electric system.

ISPs – Internet Service Providers: Companies providing Internet access to consumers and businesses, acting as a bridge between customer and infrastructure owners for dial-up, cable modem and DSL services.

IT: Information Technology.

ITCS – Interstate Transition Cost Surcharge: A balancing account that records the difference between the full rate for an energy utility's interstate pipeline capacity reserved for the noncore and brokering revenues received for that capacity. The balance is allocated to all customers on an equal cents-per-therm basis, except that core customers' liability is limited to 10 percent of the cost of the core capacity reservation.

IVDS – Interactive Video Data Service: A communication system, operating over a short distance, which allows nearly instantaneous two-way responses by using a hand-held device at a fixed location.