Fiber Optic Cable Support in Utility Tunnels NEC
Exploring NEC Section 770.125 for fiber optic cable support. Understanding support intervals for cables in utility tunnels using j-hooks.
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Distributed fiber optic sensing in harsh geotechnical environment like tunnels implies essential mechanical impacts for optical glass fibers, which must be reliably protected during installation and monitoring. The installation of the sensing cables along the shotcrete lining was different compared to previous installations [12, 21] since the tunnel excavation in the area of interest was already performed and the initial shotcrete layers were already applied. For that reason, small stripes of welded wire mesh were mounted to the existing tunnel lining, wh. All installed sensing cables have been interrogated using the fTB 5020 from fibris Terre Systems GmbH (Germany). Based on the Brillouin optical frequency domain analysis (BOFDA) technique, this sensing unit enables distributed measurements up to 25 kilometers within a measurement time of several minutes, a spatial resolution of 0.