Technical Paper: Overblowing Of Mini-Cables Into A Reduced Diameter Sub-Duct

In the late 1990’s BT developed their ACTION cable system which involved installing a 13mm optical fibre cable into a 20mm bore sub-duct, this resulted in a system which had a fill factor of 42%. With the development of mini-cables overblowing became an attractive option for larger sub-duct, 26 and 32mm bore and considerable success was achieved. In Europe this involved overblowing a mini-duct into the sub-duct and then installing a mini-cable into the mini-duct. With the introduction of G.657 A2 fibre a range of even smaller cables became an option, opening up the possibility of overblowing these cables into a small sub-duct which already contains an active optical fibre cable. This paper, presented at the Technical Session of the International Wire and Cable Symposium 2016, focuses on the development of the cable and installation practices that proved that this was a very cost-effective option.