Abstract: A plurality of optical fiber ribbons, each containing a plurality of optical fibers, are loosely enclosed in a substantially fluid impervious tube of plastic material. A plurality of such ribbon enclosing tubes are wound in S or Z fashion around a central structural member which can be covered with a plastic material. The so-wound tubes are encircled by threads or tape to hold them in place, and a covering of helically wound yarns is applied around the tubes to provide strength. A plastic sheath is applied over the yarns, and if desired the sheath is covered with other layers. Any otherwise empty spaces within the tubes and between the sheath and the tubes is filled with a water blocking material which permits the ribbons to move with respect to the enclosing tubes and which permits the tubes to move with respect to the sheath and the central member.

Abstract: An optical fiber cable with optical fibers surrounded by a first gas blocking layer which is surrounded by a second gas blocking layer spaced from the first layer so as to provide longitudinal gas flow channels between the first and second layers. The channels are filled with a gas under a pressure above atmospheric pressure so that when the second layer is punctured, there is a gas flow and/or gas pressure drop indicating such puncturing and hence, if caused by tampering, the fact of tampering. Also, devices for indicating the gas flow and/or pressure drop and alarms and/or signal transmission terminating apparatus responsive to such devices.