This paper reports the design and characteristics of an aerial optical drop cable incorporating electric power wires, which was developed for a new π-system. The new system is called the power supply HUB π-system, in which commercial AC electric power is received at a central location of several optical network units (ONUs), and is distributed to each ONU by the aerial optical/electric drop cable. We describe the requirements for the cable, which guarantee a 20-year lifetime. We designed the cross-sectional structure of the cable, based on system requirements and operation requirements, and determined the strength wire type and diameter, based on the optical fiber failure prediction theory and a cable strain requirement. We confirmed that the cables, manufactured as a trial, have stable characteristics, which satisfy the above requirements. The optical/electric drop cables will be introduced in autumn 1999.

Recently, optical loss increases have appeared at high temperatures in some of the optical drop cables, introduced for FTTH field experiments. Optical drop cable is installed from homes to aerial facilities, and consists of an optical fiber cable part and a self-supporting wire part. Fiber micro-bending is caused by cable sheath buckling in high temperature environments when the cable is bent with the cable part inside. Moreover, adhesion between the steel reinforcing wires and the cable sheath is effective in preventing this fiber micro-bending, which induces loss increases. This paper also shows the most suitable range of adhesive ability in terms of both practical construction and environment.