This industry comprises establishments primarily engaged in the construction of power lines and towers, power plants, and radio, television, and telecommunications transmitting/receiving towers. The work performed may include new work, reconstruction, rehabilitation, and repairs. Specialty trade contractors are included in this group if they are engaged in activities primarily related to power and communication line and related structures construction. All structures (including buildings) that are integral parts of power and communication networks (e.g., transmitting towers, substations, and power plants) are included. Constructing hydroelectric generating facilities--are classified in Industry 237990, Other Heavy and Civil Engineering Construction; Constructing broadcast studios and similar nonresidential buildings--are classified in Industry 236220, Commercial and Institutional Building Construction; Performing electrical work within buildings--are classified in Industry 238210, Electrical Contractors; Line slashing or cutting (except maintenance)--are classified in Industry 238910, Site Preparation Contractors; Installing and maintaining communication transmission lines performed by telecommunications companies--are classified in Subsector 517, Telecommunications; Locating underground utility lines prior to digging--are classified in Industry 561990, All Other Support Services; and Tree and brush trimming for overhead utility lines--are classified in Industry 561730, Landscaping Services.