| 摘要 |
PROBLEM TO BE SOLVED: To prevent insertion capacity from being lowered and the operating sound of a pressure gas source from becoming noisy by inserting an optical fiber through from the upper floor to the lower floor of a building of a plurality of stories. SOLUTION: Horizontal cables 2a, 2b are connected to one of pipe conduit lines 22 of a vertical cable 1 using pipe connection parts 3a, 3b to form an insertion path of an optical fiber 8, and the optical fiber 8 is inserted through the horizontal cable 2b laid on the lower floor than the horizontal cable 2a, from the end part of the horizontal cable 2a in the insertion path via the vertical cable 1. The horizontal cable 2a on the upper floor side and the horizontal cable 2b on the lower floor side are partially formed in a circular bundle taking account of bent parts in the actually laid state, and bending is applied to the horizontal cable 2a, 2b side of the pipe connection parts 3a, 3b. The weight of the optical fiber 8 therefore acts in a direction of heightening insertion capacity, so that the optical fiber 8 can be inserted through with a low pressure and small gas capacity. |
