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Fill Ratio Differences From Jumpers To High-Fiber-Count Trunks

The case for high-fiber-count trunks are their impact on valuable data center real estate – the pathway for cabling. TIA-569 provides calculations to understand what percentage of tray/conduit/raceway is taken up by cabling along with a recommendation that the individual maximum fill ratio not exceed 25 percent. Though it may not be intuitive, it is a fact that a 50 percent fill ratio actually uses up an entire pathway, because the spaces between cables are part of the equation. With this in mind and referring to Figure below, the first option using more than 3,000 jumpers isn’t an option at all. However, the second cabling option (48 72-fiber trunks) does work in a 4 x 6-in tray but not quite as well in a 4 x 4-in tray. Both tray sizes can easily accommodate the six 576-fiber trunks option.