This industry comprises establishments primarily engaged in installing and servicing electrical wiring and equipment. Electrical contractors included in this industry may include both the parts and labor when performing work. Electrical contractors may perform new work, additions, alterations, maintenance, and repairs. Installing and maintaining telecommunications lines by telecommunications companies--are classified in Subsector 517, Telecommunications; Constructing power and communication transmission lines--are classified in Industry 237130, Power and Communication Line and Related Structures Construction; and Burglar and fire alarm installation combined with sales, maintenance, or monitoring services--are classified in U.S. Industry 561621, Security Systems Services (except Locksmiths).