Electrical Consultants, Inc. (ECI) is a leading power engineering consulting firm that provides engineering and design services for the electrical power industry. ECI was founded in 1985 and is headquartered in Billings, Montana, with additional offices in South Dakota, Wyoming, and Washington. The company specializes in power system studies, substation design, transmission line design, and distribution system design. ECI serves clients in the utility, industrial, and renewable energy sectors.