How Anyone Can Splice Fiber Optic Cable

Fiber optic internet connections are rapidly becoming a critical part of data networking and global communications. In other words, it’s pretty important. Everybody loves the speed and reliability of this relatively new internet type, but sometimes something goes wrong inside the cable.

That’s when the call goes out like the bat signal in the sky for a qualified cable splicer.

Installing, maintaining, and repairing fiber optic cable isn’t rocket science, but it requires specific tools and skills. The primary skill you need to keep your fiber network tuned and operational is learning how to splice fiber. 

While the fiber cable splicing procedure might be different than anything you’ve done before, a little practice and you’ll have it down. 

So, what is fiber optic splicing? We thought you’d never ask. Buckle in, and let’s learn all about it.

Understanding Fiber Optic Splicing

Before we jump into the nuts and bolts of fiber optic splicing, it would help to know how fiber cable differs from other types of internet that also use cable, which would primarily be Digital Subscriber Line (DSL) and cable internet.

A DSL connection comes in through the copper cables in your telephone jack. A cable connection arrives via the copper lines in the coaxial cable that also carries your cable television signal. 

A fiber optic cable is an entirely different kind of beast. Its core is constructed of hundreds (or more) strands of glass fibers that relay data through flashes of light rather than electric pulses through a metal wire. 

With this basic understanding of fiber cable in mind, we can move on to joining two cables together through splicing. Knowledge of fiber optic splicing allows amateur or certified technicians to work with these fragile cables to repair or maintain a network.

When Splicing Fiber Optic Cable is Needed

If you’re new to the field of fiber optics, it would be helpful to understand what type of situations might call for a cable splice. Here are the typical scenarios you’ll run into.

• A cable is damaged. Maybe a rat chewed through it, or you rolled across it with an office chair, or it was kicked in a fit of rage when the TPS report was late. Regardless of why now you have a problem. The internet signal is gone, and someone needs to cut and splice the cable around the damaged area.
• You may have two cables that need to be joined together to bring fiber optic internet from one place in an office complex to another. Odd situations like this arise all the time. This should be a reasonably simple splice if you know what you’re doing and have the right tools.
• A final scenario you frequently encounter is when you need to lengthen an existing fiber cable. This is similar to the circumstances just above but with a slight twist. Regardless, you have an existing cable and need to connect another cable to it.

What you’ll find as you gain knowledge of fiber cable splicing is that the details aren’t always necessary. The splicing skills you learn can be deployed almost uniformly in a wide range of circumstances.

Tools Needed to Splice Cables

As might be expected with a fancy newish technology like fiber cable, there are a few particular tools needed before you make a splice attempt. We’ll get into more detail in a little bit, but we will list the tools below so you have at least seen a reference to them.

You should also be aware that there are two main methods of fiber splicing, fusion and mechanical, and the tools you need for each will vary.

• Fusion splicer
• Fiber cable stripper
• Fiber adapters

With these tools set firmly in mind, let’s jump into the two methods of doing an actual splice.

Fusion vs. Mechanical Splicing

Mechanical splicing is the more primitive of the two methods. The result is creating a patch that holds the two ends together in precise alignment but doesn’t splice them into one solid piece. Though it might seem crude, a mechanical splice is a legitimate way to bring two fiber cables together to ensure the continuity of the signal.

The other method is known as fusion splicing. As you can probably guess from its name, a fusion splice uses heat to fuse or weld two ends together so that they become a single continuous piece of fiber optic cable.

Step-by-Step Guide to Mechanical Splicing

Now that you understand the big picture regarding mechanical splicing, let’s get into the details of how to do the thing yourself.

Step #1: Strip the Fibers

For this, you’ll need a special set of electrical pliers that allow you to strip away the outer coats, buffers, and protective layers, leaving only the inner optical fibers. Take care with this process because it’s easy to damage the goods inside.

Step #2: Cleave the Fibers

Cleaving the fiber simply refers to the fact that the resulting fiber you have at this point might have irregularities at the end. Cleaving means that you create a clean, straight break with pliers or another cutting device. Without a proper cleave, you can expect a signal loss in the finished product. After cleaving, use common isopropyl alcohol to clean away any remaining debris.

Step #3: Fuse the Fibers

Now for the exciting part. Get out your mechanical splicing device and lay the two cleaved ends in it, bringing them together into a close and straight alignment that allows light to pass through. 

Step #4: Protect the Fibers

The two ends are not going to stay in proper alignment. You need to apply index-matching gel to the splice. This type of liquid cement solidifies the splice while allowing light to pass through unhindered.

Voila! You have just performed a mechanical splice. If this is your first attempt, there’s a good chance it will look crappy and not work very well. No worries. That’s what practice is for. Break another cable and try to fix it. Do this enough times, and you’ll be well on your way to a high-paying fiber cable installer career.

Step-by-Step Guide to Fusion Splicing

The next fiber splice we will touch on is fusion splicing. Learning how to fusion splice fiber might be complex, but don’t worry. You don’t have to be perfect—practice, practice, practice.

Step #1: Prepare the Fibers

This step is the same as in step #1 of the mechanical spicing process. The goal is to use either mechanical strippers or thermal strippers to get rid of all the protective outer coatings. You will be left with naked fiber optics.

Step #2: Cleave the Fibers

This step is also similar to the second step of mechanical splicing. A point to make - since fiber optic is made of glass, you should realize that the cleaving process does not involve cutting. What you are doing with a cleave is making a clean break of the glass. The result must be perpendicular fibers that are broken straight across.

Step #3: Join the Fibers

Now it’s time to drag out your trusty fusion splicer and join the two ends into one continuous piece. As with the mechanical method, lay both ends into your splicer. Make sure they are aligned precisely, then introduce the built-in electric arc to melt and fuse them.

Step #4: Secure the Fibers

Last but certainly not least, you want to protect your new splice from damage. This is done by placing a protective heat shrink sleeve around the spliced area. Make sure to choose a sleeve specifically designed to be used with fiber cables.

Choosing Between Mechanical and Fusion Splicing

Now that we’ve gone through both splicing processes, an obvious question arises. Which should you use? Well, it isn’t rocket science, but it might make a difference depending on the particular splicing circumstances you face.

Here are the factors we’d suggest you focus on.

Cost

Most decisions come down, at least partly, to cost, and fiber cable splicing is no different. The question to ask yourself is which type of splice will yield a better result for the cost? The primary consideration is upfront costs. Buying the initial tools and supplies for a mechanical splice is cheaper at around $1,500, but each splice will ultimately cost about $25. 

Compare this to fusion splicing tools and supplies, which could run upwards of $30,000 or more for the initial buy-in. After that, though, the price per splice is only about a buck. There’s the math, so it’s up to you to decide which way to go. The ultimate cost consideration probably comes down to whether your splicing is going to be a one-time or very few times or something you do more regularly.

Splice Performance

There’s no doubt that a mechanical spice does not tend to be of as high quality as a fusion splice. Due to the crimping of ends, you should expect more signal loss and a greater chance that the splice will be accidentally pulled apart and require another fix.

Since a fusion splice fuses the ends, it is stronger and results in less signal degradation. The final consideration here is likely to be how critical it is that the most signal be retained and that the fix is as permanent as possible.

Time and Environment

It should be no surprise that you might not have all the time in the world to complete your splice. There’s a good chance that there will be forces (bosses and managers) pushing you to complete the splice quickly. Maybe an entire company’s operations depend on getting the internet back up and running.

In other words, which process is quicker? The answer to this is that a mechanical splice is faster to return to operational status, albeit at reduced efficiency. If you have all the time in the world, consider doing a fusion splice. If not, a mechanical splice might be the best choice.

Don’t forget that you could also do a quick mechanical splice and then come back and redo it at some point in the future with a fusion splice.

Best Practices for Splicing Fiber Optic Cable

The worst kind of fiber splice is one you have to go back in and do again because you did a lousy job in the first place. Luckily, you were wise enough to read this article and know what signs to look for that tend to increase the chances of successful splicing.

Know the Signs of a Good or Bad Splice

There’s not much sense in even attempting a fiber splice unless you can tell the difference between a good one and a bad one. While a single article like this won’t make you a grizzled old fiber-splicing veteran, it will hopefully begin to settle in your brain the difference between a successful splice and one that will eventually have to be redone.

What should you look for when trying to tell which splices are good and which are bad? And remember, a bad splice can cause severe signal degradation, enough that your connection could become unusable. In other words, it’s worth knowing the difference.

Bad Splice: Look for bubbles, bulges, black shadows, or a thick black line at the splice. These are all signs that something is amiss.

Good Splice: On the other hand, a good splice is evidenced by a transparent, non-reflective splice area. Look for a white line or a blurred thin line at the splice. The fewer flaws noted, the better, but flaws aren’t necessarily a sign of a degraded signal. For example, the wire itself might exhibit an offset while the actual optic fibers inside are perfectly spliced. The only real way to get where you can discern these features at a glance is through experience, but it would be a good idea to put this article somewhere you can find easily for reference.

Keep Your Splicing Tools Clean

If you were paying attention to our detailed descriptions of mechanical and fusion splicing, you noticed several references to cleaning the fiber being spliced periodically. The reason is simple. If you introduce dirt or other junk into the splice, it’s likely going to result in a degraded signal.

You can’t have a clean splice without clean tools. Stick this in your brain, and don’t forget it. Without clean tools, you won’t have a clean splice. Simple rubbing alcohol and clean wipes go a long way in achieving the level of squared-away scrubbing you need when splicing fiber optic cable.

You’ve probably noticed a lot of talk about signal degradation. That’s by design. There’s not much point in splicing a fiber cable unless you can do it while maintaining the speed of the connection. Speed is one of the main benefits of fiber. If you lose that, you might as well go back to DSL or cable.

Taking Care of Your Cleaver

The cleaver is a critical tool in fiber splicing. It is the machine used to create a small score or break in the glass fibers. After that, slight downward pressure should result in a clean break. A dirty, worn, or neglected cleaver makes it hard to create the kind of quality score that breaks cleanly, leaving you with…wait for it…signal degradation.

Without going into depth here about precisely how you should maintain your cleaver - because there are different types - just keep it in mind to read the owner’s manual thoroughly and don’t fall short on taking care of your equipment. They are too expensive to take a haphazard approach in this area.

Set Fusion Parameters Systematically

A last hint that hopefully won’t sound too wonky. Like the title up there says, when using your fusion splicer, you don’t want to be randomly spinning up different settings all the time the first time a problem surfaces.

When we say settings, it’s mainly a reference to fusion time and fusion current. It’s these features that have the most effect on the splice quality. If you’re having trouble, change only one variable at a time and only a little bit at a time as you try to zero in on the best result.

Each job might require slightly different settings since fiber cable is not uniform. The bottom line here is not to start spinning dials and twisting knobs randomly. Take your time. Focus on patience and precision.

If you don’t, you’re going to mess up a lot of splices and end up with…anyone care to guess? Signal degradation!

Final Thoughts

When we talk about fiber optic networks, we’re talking about splicing. It’s impossible to install, repair, or maintain a workable product unless you have splicing down very, VERY well. There’s probably not another singularly important technique to master when working with this new type of internet connection and its accompanying material. Without mastering the knowledge of splicing, you might as well forget about having a quality fiber connection.

As you head out into the wild, blue yonder of fiber cable splicing, don’t be intimidated by the technology. You have two methods to learn, mechanical and fusion. Once you have them down, it’s practice, practice, practice.

While fiber optic internet is just coming into its own and is available to only a small percentage of Americans presently, expect that to change as internet service providers build out new infrastructure to carry this speedy new connection technology. For a list of fiber optic services available in your area right now, drop your zip code into our free search tool.

Keep in mind that this is a field where service is expanding rapidly. While the list of local providers might not be impressive now, expect things to change quickly.