Data Center Cabling Solutions

Field Termination vs. Factory Termination (Pre-Termination)

Fiber optic cable termination, the process of installing a connector onto the ends of a cable, is the single most important step for successful fiber optic infrastructure performance. Here’s why:

  • Proper cable termination will ensure hardware performs with minimal signal loss, and better performance, at optimal speeds.
  • Troubleshooting system issues is made more efficient and resolved more quickly when cable connectors are attached with care to prevent contamination and breakage.

There are two termination options used in today’s market. The first is field termination, which consists of securing the connection on-site. The other is factory termination or pre-termination, in which the fiber arrives on-site with the connectors attached and ready to install.

Determining which connection process type is best for your project requires weighing several pros and cons. But it’s important to first understand why quality connections are so critical.

The termination’s first priority is to minimize insertion loss (IL) and return loss (RL). IL is critical in all applications. RL is most critical in singlemode applications and additional testing is required to measure results. Both types of loss are caused by numerous factors, such as the connector’s end-face geometry, end-face contamination, or sloppy installation processes.

Field Termination

This method is popular in networks such as campus environments, remote medical, and K-12 educational facilities. This method enables the user to determine fiber lengths on-site and allows flexibility for cutting at the exact point needed.

Connectors are added in the field with specialized tools and consumable kits. They can be chosen as needed by either the brand or style of connector favored by the installer or end-user.

There are three current methods to field terminate:

  1. Mechanical - This method features the process of cleaving a fiber and attaching the connector through a mechanical process.
  2. Epoxy Polish - This method requires gluing the connector onto the cable and polishing the connector into spec. This is no longer a common method due to installation time and consumable requirements.
  3. Pigtail Splicing - This method requires fusion splicing a pigtail (half of a patch cord) on to the cable. Angled connectors and most singlemode applications require this method. Mechanicals are now becoming more popular methods for these types of applications.

Field Termination Advantages

  • Cable length flexibility
  • Length preciseness
  • Very little up-front planning time required
  • Bulk cable product is generally readily available
  • There is extra cable available in the event of breakage during a long and difficult pull

Field Termination Disadvantages

  • Requires various kits and specialized tools and instruments
  • Costly test equipment needed
  • Quality depends on skill, experience, and components
  • Lack of clean conditions and proper equipment access can lead to test failures and duplicated work
  • Higher quality levels of factory performance cannot be replicated in field
  • Time consuming, average 30+ minutes per connector
  • True costs are not always apparent. They can slowly stack up with labor and products needed.

Factory Terminated (Pre-Terminated)

With the luxury of proper planning, factory terminated cables are more cost-effective, better performing, and more reliable than field-termination cables. Shipped from the factory in pre-measured lengths, cables arrive with the fiber optic connectors already installed with factory precision and consistency, meeting standards’ guidelines and required loss measurements.

This method is popular with financial institutions, healthcare, and transportation organizations where data speed and reliability is critical.

Factory Terminated Advantages

  • Factory polish quality featuring end-face geometry consistency and inspection
  • Minimum possible insertion loss
  • Tested results: product met requirements set prior to leaving factory and arriving at destination
  • Cable quantity reduction due to multiple fiber break-out connectors on a single trunk
  • Certified for higher speeds such as 40, 200, and 400 GB/s

When utilizing a factory-installed fiber optic connector, the geometry of the glass is cut and cleaved consistently, polishing is automated, and the epoxy is set and cured to proper specifications. This achieves the proper fiber geometries critical to performance.

There will be few material blemishes, smudges, or contamination on the cable end connector, thereby promoting lower insertion loss. The factory also maintains quality assurance inspections for the polish, connection quality, and final insertion loss, utilizing the latest calibrated high-end test equipment before any cable is shipped.

Factory Terminated Disadvantages

  • Exact lengths required at time of order
  • Fiber trunks could potentially be too bulky for conduits
  • Without proper precautions, long or complicated pulls can damage connector ends
  • If a fiber is broken while installed, it must be deinstalled
  • Cable loops or slack forms if not measured properly

When to Use Field Terminated vs. Factory Terminated Fiber Optic Cables

Pre-terminated cable connectorized ends are inherently higher quality and provide more reliable and consistent performance than field termination. But the size of bulk created by the connector ends and small diameter cable conduits mean that pre-terminated applications are sometimes limited.

Without question, the best applications for factory-terminated cables are in data centers, network rooms, or in any smaller data transmission areas. Cabling in these areas is usually run overhead or underneath the floors in/on a basket tray, ladder, or fiber runners.

These conveyances average 6-inch minimum width and three to six inches height. This is more than adequate to allow easy laying or running of pre-terminated cabling. The lower dB loss generally provided by this controlled end-capping will contribute to the ROI in high-end hardware meeting its deliverables at high-speeds.

Field terminated cables are best used when installation of the fiber is over very long distances, through small diameter or shared space conduits, or other paths not easily measured. Field terminated cables provide more flexibility in these scenarios and pre-terminated cable connectors can be damaged with long or awkward pulls.

Since termination cost is relatively static, in longer cables there is more equity in the bulk cable than in the pre-terminated end. In this case, field termination makes more sense in order to avoid the potential cost of having to deinstall, then reinstall or field repair the cables due to connection issues.  

Which to Select?

Selecting one or the other depends on the characteristics of the location, environment, or application. If possible, the user should seek the advice of an expert in the field for best practices in managing conduits and expected results. Factors such as environmental conditions, exact length, difficulty or path of pulls, and budgeting, affect the decision.

With the significant growth and constant change in data centers, factory terminated fiber has become the choice for most data centers. Improvement in planning methods and deployment techniques, combined with high demand for increased bandwidth across all connections, has made field termination relatively obsolete in this space. Field termination is typically used only when the use of factory terminated product is restricted by distance or significant installation obstacles.

Learn all about installation best practices in our Fiber Optic Cable Installation Guide - just click here.