Power Lines and Substations Web Glossary
| Term | Description |
| Ampere | Often abbreviated as “amp,” this unit of measurement of electric current is akin to cubic feet of water flowing per second. |
| Base Load | The nearly steady level of demand on a utility system, as opposed to peak load, which is that portion of customer demand that rises and falls based on weather, season, time of day, etc. |
| Capacity | The load for which an electric generating unit, other electrical equipment or power line is designed to accommodate. |
| Condemnation | The legal process of acquiring land from an unwilling seller for just compensation under the power of eminent domain as defined by state law and court action. For an electric utility, condemnation is typically a last resort and infrequently used. It prevents individual property owners from impeding construction of electrical facilities needed to serve the broader public. In recent years, Georgia Power's overall condemnation rates averaged less than three percent. |
| Conductor | Any material (such as a power line) that allows easy transfer of its electrons. Aluminum and copper are excellent conductors, although many substances will conduct electricity, including water, other metals, wood, soil and the human body. |
| Demand charge | A separate charge based upon the demand for electric service by a commercial or industrial customer, based on the investment in facilities necessary to serve them. |
| Distribution lines | Power lines, like those in neighborhoods, used to carry moderate voltage electricity that is "stepped down" to household levels by transformers. Distribution line voltages vary, but typically operate at less than 46,000 volts. |
| Easement | Similar to a Right of Way; an easement grants a legal right to use another's property for a specific purpose. It also refers to the actual strip of land used for such purpose. |
| Electricity | The motion of electrons through a conductor. |
| Eminent domain | The authority to acquire land from a private owner for the benefit of public use after the payment of just compensation. |
| Feeder Line | A primary or main distribution power line that distributes or "feeds" power from a substation to the surrounding area, like spokes from a wheel. Feeder lines typically have many smaller "taps" or "pull-off" lines that lead to transformers and service lines serving homes and businesses. |
| Franchise fee | A local tax imposed on utilities for the privilege of providing a service within city limits. |
| Guy Wires | Strong wires or cables under heavy tension, used to stabilize a tower or pole. Guy wires do not normally carry electricity, however, damage to a guy wire or nearby power lines could cause a guy wire to become energized and dangerous. Caution children not to play or swing on guy wires. |
| High voltage | Voltage greater than 100,000 volts. |
| Insulator | Any material that prevents the easy transfer of electrons. Insulators like glass, ceramics and rubber do not readily conduct electricity. Impurities, cracks, distance, voltage level applied or other conditions degrade insulating properties and may allow conduction. Insulators on power poles are usually bell-shaped devices holding wires away from the poles and other lines. |
| Kilowatt (kW) | 1,000 watts. |
| Kilowatt-hour (kWH) | A unit of electricity consumption. For example, one kilowatt-hour equals the amount of electricity needed to burn ten 100-watt light bulbs for one hour, or to run one 1000-watt hairdryer for one hour. |
| Kilovolt (kV) | 1,000 volts. |
| Load | The total customer demand for electric service at any given time. |
| Megawatt (mW) | One million watts or 1,000 kilowatts. |
| Natural monopoly | When the cost of utility service, such as gas, water or electric service, is minimized to customers if a single enterprise is the only seller in the market. |
| Peak demand | A one-hour period in a year representing the highest point of customer consumption of electricity. Both the power plants and the facilities used to transmit and distribute the power must continuously be able to meet customers' peak demand or else power interruptions will occur. In other words, an electric system must be built ahead of time with enough capacity to meet expected peak demand. |
| Power pool | A regional organization of electric companies interconnected for the sharing of reserve generating capacity. |
| Public Service Commission | A state regulatory body typically charged with regulating service providers such as electric and natural gas utilities, telecommunications providers and others. Commissioners are elected or appointed depending on state law. The Georgia Public Service Commission is an elected body of five commissioners serving staggered six-year terms. |
| Public utility | A business enterprise rendering a service considered essential to the public and, as such, subject to regulation. |
| Right of Way | Abbreviated "ROW," a right of way grants the legal right to pass over or cross another's property for a particular use, such as building a road or power line. It also refers to the actual strip of land being used or set aside for such purpose. |
| Service area | TThe territory in which a utility is obligated to supply service. |
| Service or Service Line | The lower voltage power line that delivers power from the transformer to the home or business. This may be a set of three separate wires, but is usually a twisted set of two black wires and one bare metal wire called "triplex" (pronounced try-plex). |
| Substation | A facility that serves three primary purposes: - Switching (connecting or disconnecting electrical circuits so as to route power where needed) - Voltage change (typically lowering voltage levels using transformers before sending it out on transmission or distribution lines) - Voltage control ("fine tuning" the voltage as needed using voltage regulators and other electrical equipment) A typical neighborhood substation is something like a "distribution center" for electricity. Transmission lines bring power to the substation, which serves as a hub with distribution feeder lines extending like spokes on a wheel to serve the surrounding areas. |
| Transformer | Electrical equipment designed to increase or decrease voltage, as needed. When mounted on poles, they usually look like gray metal barrels. When used with underground service, they are often a green metal box mounted to a concrete pad. In substations, they will often resemble large gray metal boxes. |
| Transmission lines | Power lines normally used to carry high voltage electricity over relatively long distances to substations. At the substation, the voltage is "stepped down" in a transformer for distribution to individual customers. Transmission lines typically operate at 115,000 volts, 230,000 volts or 500,000 volts. |
| Underground | Typically refers to electric distribution lines installed underground. Rarely, transmission lines are buried as well. Usually called "cable," underground wires may be placed in special tubes called conduit or buried directly in trenches |
| Volt* | The unit of electromotive force or electric pressure, akin to water pressure in pounds per square inch. |
| Watt* | The electrical unit of power or rate of doing work. |
*Visualize the difference between a watt and a volt by imagining water flowing through a hose into a bucket. Voltage is similar to the water pressure in the hose and wattage is the amount of water going into the bucket. |
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