Fiber-optic splicing vs. factory-assembled fiber-optic cables

Data centers are constantly growing in response to the demands of new business processes and ever increasing data rates. The IT cabling infrastructure is the basis for trouble-free data transfer and the reliable interaction of all the active components and applications in the data center. This makes professional installation all the more important. The shortage of skilled labour is currently a major challenge. If tasks are entrusted to insufficiently qualified personnel then this increases the risk of human error and consequently of data center downtimes and malfunctions.

Cost-efficiency is also playing an ever more important role. Outlay should be kept to a minimum in terms of both time and costs. One key factor alongside cost-efficiency when planning a new data center or extending or expanding an existing one is that it should be ready for occupation and commissioning as quickly as possible.

Various methods can be used to install the fiber-optic cabling in a data center. A number of criteria need to be considered when choosing the installation method.

This blog focuses on comparing a single-fiber splice solution with a factory-assembled plug-and-play fiber-optic cabling system.

Table of contents:

• Definition: Factory-assembled fiber optics vs. (single-fiber) splice solution
• Handling and professional testing of fiber-optic cabling
• Failure-proofing and security of factory-assembled fiber-optic cabling vs. splice solutions
• Economic comparison: Time- and cost-efficiency
• Influence of the application environment on the installation method

Factory-assembled fiber-optic cabling

When cables are factory-assembled, fiber-optic plug connectors are mounted on the fiber-optic cables in the production facility using ultra-clean, state-of-the-art industrial processes and quality assurance measures. The result is plug-and-play cabling systems of the desired length that are ready for immediate connection. The insertion loss of the cables is fully measured during the in-plant assembly process and the cables are accompanied by their own dedicated measurement reports. At the installation site, the cables simply have to be pulled in and the cable dividers and fiber-optic connectors mounted in the distribution panels associated with the cabling system.

(Single-fiber) splice solution

In the process known as fusion splicing, the fibers of the cables that are to be joined are fused together by means of an electric arc in a fusion splicing machine. This technique is also used to attach fiber-optic connectors that have been factory-mounted on short fiber-optic cores (known as fiber-optic pigtails) to previously laid fiber-optic cable lengths in splice panels. When installation has been completed, it is necessary to perform an acceptance measurement, generally using OTDR.

If a fiber-optic splice solution is chosen then specialist personnel who have also been trained to use a splice machine are required. They must also have specialist knowledge of performing acceptance measurements – in most cases using OTDR. This is because conventional spliced fiber-optic solutions must undergo on-site metrological testing prior to acceptance.

Because the time required to install factory-assembled plug-and-play cables is reduced to the absolute minimum, the installation personnel are present for only a very short period in the sensitive high-security areas of the data center. This further protects the data center against accidental or malicious manipulations or sabotage.

Because cabling systems consisting of factory-assembled fiber-optic cables have no splices and are manufactured to the very highest quality, they have the lowest link attenuation that can be achieved by cabling solutions.

By contrast, fiber-optic cables lying more or less exposed in the splice cassettes of single-fiber splice cabling solutions are not optimally protected against environmental factors. Fibers in splice cassettes are exposed to the ambient air and this may cause them to age. This may lead to increased attenuation or to the fracturing of the fibers.

When costed rigorously and correctly, the overall costs of factory-assembled fiber-optic cabling systems are usually lower than those of splice solutions. The reason for this is that the total amount required for all the components needed in a splice solution – such as the loose cable lengths, pigtails, splice cassettes, splice protectors and holders – is usually higher than the cost of cabling using factory-assembled fiber-optic cables. Above all, though, expensive specialist personnel are needed to perform the extremely time- and equipment-intensive splicing operations themselves. Significantly less time and specialist knowledge is required for the installation of factory-assembled fiber-optic cables.

The application environment and the requirements placed on the device interfaces play an important role when choosing the installation method. It is also necessary to take account of future applications and the scalability of the cabling.

In the light of all the benefits discussed above, users should start by considering the possibility of a factory-assembled fiber-optic cabling solution. Only if this is not feasible due to the particular space constraints is a splice solution the better choice. There are times when splicing is the right solution, for example for cross-building cabling or in very cramped or already well-filled conduits, or when there is not enough space to pass through factory-assembled cable ends due to fire compartments.

A number of criteria need to be considered when choosing the installation method. The choice between a splice solution and factory-assembled plug-and-play cabling depends on factors such as project complexity, installation time, budget, requirements in terms of flexibility and reliability or the available specialist personnel.

In particular in the case of mid-sized through to large data center installations, the factory-assembled, structured fiber-optic cabling systems first introduced in 1991, including by Rosenberger OSI as one of the pioneers in this technology, have established themselves as the standard solution.

The growing success of this method is easily explained: Factory-assembled fiber-optic cabling systems guarantee not only high-performance and reliable data transfer between IT hardware but also permit considerable time – and therefore financial – savings during installation. The money saved is then available for ongoing development of the data center.

Last but not least, Annex C of standard EN50500-2-4:2023-09 “Information technology – Data center facilities and infrastructures – Part 2-4: Telecommunications cabling infrastructure” - recommends the use of factory-assembled cabling for availability classes 3 and 4.