Fiber Optic Uncut cables are suitable for use in scenarios with multiple branch connections due to their ease of stripping and core splicing. They can be used in the backbone, distribution, introduction, and household (entry) sections of broadband access cable lines.

But how much money can be saved by using easy to cut fiber optic cables (uncut cable) in broadband access cable lines?

This article will compare and analyze the engineering costs of using uncut optical cables and ordinary optical cables in the same scenario (hereinafter referred to as the “two schemes”).

Due to the lack of centralized procurement for uncut optical cables, when conducting cost analysis, if more than 24 cores, this article refers to the price of ordinary cables, the price of 24 core and 12 core uncut cables with tight buffer is calculated at 1.2 times the price of ordinary cables. The estimated unit price of the investment refers to a similar project of an operator in some eastern provinces in 2023. The length of the laid optical cable includes the length required for the connectors and cable terminations.

Introduction Section Cost (Drop Cable Section)

Vertical wiring inside buildings

Due to frequent branch connections, the introduction section is the most suitable section for using uncut cables. For example, there are two options for vertical wiring within a building, as shown in Figure 1.    

If one fiber distribution box is set every 3 floors, and the spacing between fiber distribution boxes is estimated to be 12 meters, the main workload and investment comparison of the two schemes are shown in Table 1.

When using uncut cables for vertical wiring in buildings, the number of cores in the cables often decreases very little, resulting in a longer total core length of the cable line. However, due to the small number of fiber cores used for splicing, using uncut cables will significantly reduce the project cost. The investment of uncut cables is only about 68.5% of that of ordinary cables.

FTTH Fiber Access

First, let’s take a look at the FTTH access network in rural areas. The network structure is shown in Figure 2.

The fiber optic network structure of the two schemes are the same, with the main difference are the different splicing method in the fiber optic splice enclosure and the fiber optic splitter box. This also results in an investment of only about 90% of that of ordinary cables if use uncut cable.

The main workload and investment comparison of the two schemes are shown in Table 2.

The network structure of FTTH access network in urban areas is similar to Figure 2, but the density of cable distribution boxes is significantly higher than that in rural areas. Usually, the distance between adjacent fiber boxes in urban areas is about 30% of that in rural areas. According to the estimation method in Table 2,  the investment for using uncut cables in urban areas is about 85% of that for ordinary cables.

Cost of Entrance Section (Household Section)

When using uncut cables in the entrance section, each core needs to be terminated in the fiber distribution box, and an introduction box needs to be set at regular intervals, as shown in Figure 3. This also leads to higher overall installation costs when using uncut cables in the introduction section.

For example，setting up an introduction box every 10-15 meters in urban buildings or street shops, the investment of uncut cable is nearly twice that of ordinary cables. The main workload and total installation cost of the two schemes are shown in Table 3.

But in rural areas, setting up an introduction box every 50-100 meters, the installation cost of using uncut cables is equivalent to that of ordinary cables.

Therefore, from the perspective of overall installation costs, in areas with a high concentration of urban users, it is not advisable to use uncut cables for the entrance section; In areas with low user density such as rural areas, when there are multiple incoming cables on the same route, use uncut cable.

Cost of Backbone and Distribution Sections

The backbone and distribution sections generally adopt a ring or tree network structure, as described in the article “Network Structure of Backbone Optical Cable Lines”. When using tree networking, the main workload and investment of the two schemes are basically the same.

When using ring networking structure, the fiber core is branched and spliced at the cross cabinets, the remaining fibers are directly coiled in the fusion splice tray to maintain direct connection. For example, at GJ01 in Figure 4, only the fiber cores # 1~# 24 and # 121~# 144 need to be connected at the end, and the remaining 96 cores can be directly connected.

If the length of the 144 core cable loop in Figure 4 is 3500 meters, the main workload and investment comparison of the two schemes are shown in Table 4.

Due to the much lower density of splicing points in the backbone cable compared to the introduced cable, the investment reduction (less than 10%)  of using uncut cables in the backbone is lower than that of the introduced cable in terms of reducing the percentage of project cost. However, in the backbone section，the number of fiber core connections at each intersection is relatively large, and the use of uncut cables has a significant effect on reducing project costs.      

So in broadband access projects, the proportion of investment savings of uncut cable compared to ordinary cables is related to the density of the connection points and the number of fiber cores routinely connected at each connection point. In scenarios where high density of connection and a large number of fiber cores routinely connected at each connection point (such as vertical wiring in buildings), investment can be saved by more than 30%. In conventional backbone/distribution cable lines and FTTH access projects, investment can generally be reduced by 5% to 20%. The use of uncut cables in the entrance section usually cannot reduce direct installation and maintenance costs.