Smart Building

Adapter Frame or Cassette? Empty or Preloaded? How Do You Decide?

Benoit Chevarie

In a fiber project, there are several decisions that need to be made when it comes to splicing and connectivity.

One of the choices you need to make involves selecting between fusion splicing and field connectors (mechanical splicing).


If you’re dealing with lots of fiber – inside a stadium, with a distributed antenna system or in a fiber entrance cabinet where fiber enters the building, for example – the answer is usually fusion splicing.


Because of its ability to ensure an excellent connection, a fusion splice results in a better-performing connector. Fusion splicing also saves lots of time and reduces costs compared to mechanical splicing. The more splicing you do, the more you can save per splice. Connectors cost less and the optical fibers are fused using heat instead of being “joined” together. It’s fast becoming the preferred option for fiber termination.


Once you decide between fusion splicing and mechanical splicing, there are a few more choices to make.


Adapter Frames or Splice Cassettes?


In regard to fiber connectivity, we often hear the question: “Can’t I just use adapter frames instead of splice cassettes to save money?”


When you crunch the numbers, the answer is: Sure, you can use them … but, no, it won’t reduce material costs like many people expect.


When using adapter frames, don’t forget that you also need to purchase pigtails and splice trays for your splice connectors.


When weighing the two options, it’s not as simple as comparing price tags on adapter frames and pigtailed or splice cassettes. Comparing those two numbers without context makes a splice cassette look more expensive, but it’s the only component you need.

Everything is already included inside.


If you’re using fusion splicing to complete 36 or more terminations, then your price per termination using a splice cassette is the same as using an adapter frame, splice protector pigtails and splice tray. Separately, each component may cost less than a splice cassette; added up, however, the price difference becomes negligible.


Using an adapter frame is also much more complex, which could increase labor costs.


Empty or Preloaded Cassettes?


Once you’ve decided on cassettes, there’s one more decision to make: choosing between empty and preloaded cassettes.


Using an empty cassette means exactly what its name implies: You need to purchase the cassette, pigtail and fusion splice protectors … which means you need to look up part numbers and order each component separately.


Preloaded cassettes (pigtail splice cassettes), on the other hand, already include everything you need inside. Through Belden, they can be ordered using a single part number to streamline planning, save valuable time and simplify bills of material.


There are a few other benefits when using preloaded cassettes, too …


  • Waste reduction. Instead of three components arriving in three separate packages that all need to be opened, preloaded pigtailed cassettes come in one package, reducing waste and saving unpacking time.
  • Less manual labor. Pigtails come preloaded in cassettes; they’re already connected. Once they arrive, you’re ready to start splicing. Just unspool the pigtail and follow your splicing procedure. You don’t need to worry about taking pigtails out of a bag, splicing them to your cables and connecting them.
  • Reduced human error. Because pigtails are connected at the factory, there’s less risk of someone accidentally connecting them in the wrong location behind the coupler.
  • Better fiber protection. In applications with high concentrations of fiber calling for mass fusion splicing, loose tube cables are often used; these cables are 250µm as opposed to tight-buffered 900µm. That means they’re more fragile and vulnerable. To avoid pinch points and strain, loose tube cables usually need to be protected inside the patch panel with a breakout kit. With preloaded pigtailed cassettes, however, the subunit (a small tube of approximately 12 fibers, typically) installs directly into the cassette. No breakout kit is needed to protect the fiber before it enters the cassette.

Once you’ve made these decisions, you’re well on your way to finishing your fiber project! If you’re not sure how to answer some of these questions, we can help. Just send us a note!