STRUCTURE OF UNDERGROUND CONDUIT, PROTECTING TUBE THEREFOR, AND METHOD FOR INSERTING CABLE THEREINTO

摘要

PROBLEM TO BE SOLVED: To reduce cable running resistance in an underground conduit and lengthen the specified distance for pulling cables. SOLUTION: Protecting tubes P are coupled together and buried underground to form a conduit. Cable guiding rollers 10 stretched halfway around the inner circumference of the protecting tube P are installed at both the ends of the protecting tube P, and guides 18 having a slope gradually elevated from the inside surface of the protecting tube P are formed at the front of the rollers 10. When a cable T is inserted into the protecting tube P, the cable T is guided by the rollers 10 and smoothly runs in the conduit. The cable T is guided to the rollers 10 by the guides 18.