Abstract: An optical fiber unit for air-blown installations includes a number of optical conductors, a first layer of resin material, a second layer of resin material radially outer to the first layer of resin material and a sheath of a thermoplastic material, wherein the second layer of resin material has a secant modulus higher than a secant modulus of the first layer of resin material and wherein the sheath of thermoplastic material is over and in close contact with the second layer of resin material.

Abstract: An optical cable includes an optical core and an external sheath surrounding the optical core. The external sheath includes a first material having a first, higher fracture toughness and a second material having a second, lower fracture toughness. The first and second materials are arranged so that the second, lower fracture toughness material is accessible from outside the cable along at least one longitudinally extending area of the sheath outer surface. For accessing the optical core of the cable, a short longitudinal cut, namely, few centimeters, is made with a blade in the accessible second, lower fracture toughness material. Then, its cut edges are pulled apart by hand. The pulling force causes the lower fracture toughness material to fracture, thereby propagating the initial short cut longitudinally along the sheath through its whole thickness.

Abstract: An optical cable includes an optical module which includes a strength member, a plurality of optical fibers arranged about the strength member, the optical fibers being arranged substantially on a circumference concentric with the strength member, and a retaining element arranged about the plurality of optical fibers.

Abstract: An optical cable includes an optical module which includes first optical fibers and a first retaining element arranged about the first optical fibers. The module also includes second optical fibers arranged about the first retaining element, the second optical fibers being arranged on at least one circumference concentric with the first retaining element. The module also includes a second retaining element arranged about the second optical fibers, which is also substantially coaxial with the first retaining element. This optical module with coaxial retaining elements and fibers has a particularly high fiber density, while preserving the possibility to uniquely identify all the fibers.

Abstract: An optical cable includes an optical core and sheath enclosing the optical core. The optical core includes a number of optical units having respective colors and being wound about a longitudinal axis of the cable. The sheath includes at least one non opaque longitudinal section through which a sequence of colors of the optical units is visible from outside the cable. The color sequence acts as an identifier for the cable. The cable may therefore be easily identified (e.g. amongst other cables laid down within the same duct) by a simple visual inspection of the cable's inner structure through the non opaque section(s) of its external sheath.

Abstract: A telecommunication cable includes at least one optical fiber unit surrounded by a low fire hazard halogen free polymeric inner sheath that is covered by and in contact with a peelable, environmentally resistant polymer outer sheath. At least two discrete strength members are embedded into the low fire hazard halogen free polymeric inner sheath. The cable is intended for outdoor and indoor use.

Abstract: An optical fiber unit for air-blown installations includes a number of optical conductors, a first layer of resin material, a second layer of resin material radially outer to the first layer of resin material and a sheath of a thermoplastic material, wherein the second layer of resin material has a secant modulus higher than a secant modulus of the first layer of resin material and wherein the sheath of thermoplastic material is over and in close contact with the second layer of resin material.

Abstract: An optical cable includes an optical core and an external sheath surrounding the optical core. The external sheath includes a first material having a first, higher fracture toughness and a second material having a second, lower fracture toughness. The first and second materials are arranged so that the second, lower fracture toughness material is accessible from outside the cable along at least one longitudinally extending area of the sheath outer surface. For accessing the optical core of the cable, a short longitudinal cut, namely, few centimetres, is made with a blade in the accessible second, lower fracture toughness material. Then, its cut edges are pulled apart by hand. The pulling force causes the lower fracture toughness material to fracture, thereby propagating the initial short cut longitudinally along the sheath through its whole thickness.

Abstract: An optical cable includes an optical core and sheath enclosing the optical core. The optical core includes a number of optical units having respective colors and being wound about a longitudinal axis of the cable. The sheath includes at least one non opaque longitudinal section through which a sequence of colors of the optical units is visible from outside the cable. The color sequence acts as an identifier for the cable. The cable may therefore be easily identified (e.g. amongst other cables laid down within the same duct) by a simple visual inspection of the cable's inner structure through the non opaque section(s) of its external sheath.

Abstract: A telecommunication cable includes at least one optical fibre unit surrounded by a low fire hazard halogen free polymeric inner sheath that is covered by and in contact with a peelable, environmentally resistant polymer outer sheath. At least two discrete strength members are embedded into the low fire hazard halogen free polymeric inner sheath. The cable is intended for outdoor and indoor use.

Abstract: An optical fiber cable for blown installation has a tubular central strength member about which tubes loosely housing optical fibers are stranded. The jacket is preferably formed from a high density polyethylene material and is extruded over the core on which rip cords are positioned. A water blocking compound is provided in each tube in any spaces therein which would otherwise be void. Also a water blocking material is provided between the sheath and the layer defined by the helically wound wrapping tape or binding yam in any spaces between the tubes which would otherwise be void.

Abstract: An optical fibre cable for blown installation has a tubular central strength member (114) about which tubes (112) loosely housing optical fibres (116) are stranded. The jacket (118) is preferably formed from a high density polyethylene material and is extruded over the core (100) on which rip cords (124) are positioned. Water blocking compound (126) is provided in each tube (112) in any spaces therein which would otherwise be void. Also a water blocking material (128) is provided between the sheath (121) and the layer defined by the helically wound wrapping tape (122) or binding yarn in any spaces between the tubes (112) which would otherwise be void.

Abstract: An assembly for use adjacent an earthed suspension region 20 of an all-dielectric self-supporting cable 10 suspended in an electric field at the earthed suspension region from a tower or the like for limiting dry band arcing adjacent the earthed suspension region is disclosed. The assembly includes an electrically conductive device 21 clamped to the cable remote from the earthed suspension region 20 and structure defining a current path having an arc gap connected between the device 21 and the earthed region 20.

Abstract: A device 22 for use adjacent an earthed suspension region 20 of an all-dielectric self-supporting cable 10 suspended in an electric field at the region 20 from a tower or the like for limiting dry band arcing adjacent the region 20 is disclosed. The device includes members 34, 36 for defining a sleeve 26 for fitting to the cable adjacent this region 20 and elements 38, 40, 42, 44 for defining two closures 28, 30 for the sleeve. These closures are engageable with the cable at longitudinally spaced apart locations for forming with the cable and sleeve a closed zone 32 between the closures. Use of the device maintains the outer surface of the cable dry over a portion 24 thereof adjacent the region 20 which would otherwise be susceptible to dry band arcing.

Abstract: In order to install an optical fiber cable 110 in a duct 112 a plurality of vents 130, 132, 134 spaced apart along the duct are operated such that during blowing any vent 130 upstream of the leading end 138 of the cable is closed and when there is at least one vent 132, 134 downstream of the cable leading end at least the downstream vent 132 closest to the cable leading end is open for venting gas from the duct. In this way the pressure decay and pressure gradient profiles are modified during installation to improve installation performance.