Electrical infrastructure includes the electric power lines and related equipment that deliver power to Washingtonians. Learn more about electrical transmission and how we regulate it.
How electrical transmission works
Electrical transmission lines move electricity from power plants to homes and businesses. Steel towers, wooden poles or reinforced concrete poles often support these power lines, spanning hundreds of miles. In other cases, electrical transmission lines may be underground.
Electrical transmission facilities regulate electricity before sending it to communities. For example, a substation lowers the voltage coming from a high-voltage power line to a safer level for local power lines. Substations also ensure the power grid doesn’t become overloaded when electricity usage is high.
How we oversee electrical transmission
The following types of electrical transmission facilities need our certification when building, rebuilding, modifying or expanding:
- Facilities of a nominal voltage of at least 500 kilovolts alternating current or 300 kilovolts direct current and located in more than one county and located in the service area of more than one retail utility
- Facilities located in “national interest electric transmission corridors” (NIETC), areas the U.S. Department of Energy has identified as having limited transmission for customers
Other electrical transmission facilities don’t need our approval. However, these facilities may choose to come to us for certification through our siting process. They also need to meet both of the following requirements:
- Have a voltage of at least 115 kilovolts
- Be located in multiple areas with separate land use plans and zoning ordinances
