Patent ID: 6870995

Claim:
An elongated optical fiber cable with a longitudinal axis and with more than 1000 optical fibers, said cable having a fill factor not greater than about 85% in a two inch duct and said cable comprising: a central strength member structure coaxial with the longitudinal axis; a plurality of longitudinally extending buffer tubes disposed around the central strength member structure in a single layer with each tube in contact with a pair of adjacent tubes and in contact with the strength member structure, the number of buffer tubes being greater than three and less than six and each tube having a bore of a predetermined size; a plurality of optical fiber ribbons in a stack in the bore of each of said tubes each stack substantially filling, but being loosely received, in the bore of the tube in which the stuck is received and each ribbon comprising a plurality of optical fibers in side-by-side relation and wherein the total number of optical fibers in the plurality of buffer tubes is greater than 1000; and a jacket encircling the plurality of buffer tubes, wherein the jacket has a thickness and the buffer tubes and the central strength member structure have respective outer diameters selected such that the sum of one-half the diameter of the central strength member structure, the outer diameters of the buffer tubes and the jacket thickness results in the cable having a fill factor not greater than about 85% in a two inch duct.