Construction of the outside plant of Commonwealth Telephon Company's T3 digital fiber optic system which began on October 26, 1978 was recently completed. The cable installation took place over an 8 week period. This project is one of two similar commercial fiber optic field trials currently taking place in Pennsylvania to test two different approaches in the design of fiber cables. The Commonwealth system, which is the more ambitious of the two lengthwise, spans a distance of 22 km utilizing four intermediate repeaters between the north central Pennsylvania communities of Wellsboro and Mansfield. The system, which -ras purchased from ITT Telecommunications Division in Raleigh, N.C., is being installed in conjunction with the REA. It serves as the first commercial field trial of fiber optics in an operating company environment for all three parties. When the entire system is completed in early 1979, it will carry toll connecting, intertoll, operator and special service traffic. With the installation of cable, associated splicing and repeater housings completed, this report will deal primarily with specific techniques used during the installation.