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Top 5 Causes of Fiber Optic Failure

Fiber optic networks are the best in the business — when they work.

When they don’t work, they are expensive sources of frustration.

As always, the best defense is a good offense, and you can prevent the most common sources of fiber optic failure when you simply know what they are and what causes them. So, here’s a short list of the top five causes of fiber optic failure to get you going.

Backhoe Fade

Also called JCB fade, this issue occurs when digging or construction actions sever a cable. The most common source of such damage comes from a backhoe, hence the name.

As you can imagine, this instantly kills your connection, and it’s not easily fixed. You have to run a replacement cable, and since you’re running it through a construction site, things get complicated.

The best option is to prevent backhoe fade altogether, and there’s a simple way to do this. Map your lines, and if you have to run your lines through undeveloped land, make sure those maps are available and pre-approved before you run them. This way, construction crews can avoid your cables.

Bend Loss

Next up is bend loss. This happens when cables bend too far. The extreme bend prevents the light from matching the curve, and you get signal loss. This doesn’t require a kink in the cable either. If you exceed the bend radius of your cable, you can have this problem.

Preventing this issue requires you to understand the two ways it happens. One source of bend loss occurs from design. You need a sharp bend in your cable, and you utilize a cable that can’t handle the curve.

The other source comes from mishandling cables during installation. If they are bent too much at any point, you can create kinks or curves in the fibers, and you still get bend loss — even in a straight cable run.

So, plan your bends appropriately and handle your cables gently.

Attenuation Fade

Attenuation fade has a few causes, but the end result is the same; something physically interrupts the light signal.

The most common source of attenuation fade is contamination at the endpoints of the fibers. It’s very easy to smudge your fiber ends when installing a cable, and the smudge can block or scatter light. Either way, your signal suffers.

You can also get attenuation fade when the glass is damaged but not severed or there are foreign objects inside of the cable sheath that can absorb the light.

Preventing attenuation fade is simple in concept and long in practice. Clean your fiber ends properly when you install them, and test everything at installation to ensure you don’t have attenuation fade. Installed cables that test well will not randomly contaminate later unless the cable sheath is breached. So, do it right from the start, and you will effectively prevent attenuation fade.


Fiber optics often carry polarized signals, although not all fiber optic communication is polarized. When it is, the light in the fibers is oriented in the same way. If you rotate a segment of a polarized cable run, you block the signal. A partial rotation causes partial signal loss while a full rotation can cause total signal loss.

This is entirely preventable. Painstakingly ensure that your cables are aligned according to their polarity at installation, and you won’t have this problem. Additionally, if you test your cables through the installation process, you’ll pick up on a polarization problem right away, so you can correct it immediately.

Signal Misalignment

We’re cheating a little bit with this part of the list and grouping a few problems. Signal misalignment refers to issues between transmitters and receivers. While there are a few different problems that can meet this criterion, they are all resolved by calibrating your transmitters and receivers.

One issue is when your signal amplification is too high. The amplification can overwhelm the receiver.

Dispersion occurs when signals run at different speeds, which can be a problem with cables but is often found in transmission.

Lastly, you can lose timing when the frequencies at the transmitter and receiver are not aligned.

In all three cases, you can calibrate your transmitters and receivers when you run your installation tests. Beyond that, if you ever get unexpected signal degradation, signal misalignment is a great place to begin your troubleshooting.

Those are your top five causes of fiber optic failure. There are other issues that come up now and then, but when you have these five mastered, you’ll face far less disruption in your fiber optics.

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