WCA November 2011

This simulates typical 3m distances between floors in the MDU building.

Mandrel 15x cable diameter

Each cable was pulled three times for every configuration. Figure 5 shows the pulling force for a 6x4 configuration measured for three duct with various inner diameters (ID) and with different filling ratios. Results showed that the most important factor is the number of riser tap points, which will be pulled simultaneously through the duct. However, the pulling force for different fill ratios depends also on copper twisted pairs arranged inside the duct. The total pulling force during installation should not exceed 500N. Based on duct size, fill ratio and misalignment data, the maximum number of tap points pulled simultaneously can be calculated as:

Cable held firmly in place

Over- mold

Max. # of tap points

Basket grip

Where, F# is number of floors, MF is misalignment force and PF is pulling force.

To optical test equipment

Load

3 Reliability

Cable

The qualification test plan was a variation of the GR-3122 specification, modified to reflect indoor usage.

❍ ❍ Figure 6 : Sheath retention setup

Test samples were prepared in the most common configurations; 6 x 4 – 6 tap points, each with 4f, 12 x 4 – 12 tap points, each with 4f and 12 x 8 – 12 tap points, each with 8f. For such a set of samples the following tests were performed: thermal aging, thermal and humidity cycling, sheath retention, cable flexing, compression, assembly installation, pulling through ducts, cable pulling and straight and 90° tether pull. All tested samples passed both environmental and mechanical tests without any issues.

In order to route vertical cables efficiently and unobtrusively inside buildings, Corning’s design efforts for this product focused on smaller diameter and more flexible units leading to FRNC micromodule cables as shown in Figure 3 . An additional advantage of this cable is the extremely small bend enabled by ClearCurve ® [2] fibre that allows discreet storage of fibre in the building, either for tether or for excess pigtails lengths. The flexibility and the small outer dimensions of the riser cable assembly ensure the very easy installation of the cable and routing through the wall or on the various levels of the building.

As an example for the extensive test programme the sheath retention test set-up is presented in Figure 6 .

2 Installation conditions One of the most critical issues related to cable installation is pulling through the vertical duct already installed in MDUs ( Figure 2 ). The following tests were performed to simulate installation conditions and define installation limits of the cables in terms of duct congestion. The installation pro- cess was simulated for several duct diameters and shapes both with and without copper cables already installed. Additionally, duct misalignment and gap size shown in Figure 4 were considered. Tests were performed for 3m duct pipes with different dimensions.

Electronics 35%

Passive components 15%

Labour 50%

❍ ❍ Figure 7 : Typical first installed cost [3]

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