It is easy for a fiber optic cable to break when planting new flower beds, working on drainage around the house, or renovating indoors. Unfortunately, outdoor fiber cables are often laid only 10 to 20 centimeters below the ground surface up to the foundation, making them extremely vulnerable to shovel strikes and excavation.

When a standard electrical cable breaks, splicing the copper in a junction box with approved terminal blocks is usually straightforward. With fiber optics, the situation is completely different. Here we explain why repairing a severed fiber cable is so complex and what is required.

Why Is Fiber So Sensitive Compared to Copper Cables?

An electrical cable conducts electricity through metal. A fiber optic cable conducts light signals through a glass fiber no thicker than a strand of hair, about 125 micrometers.

If the glass snaps, simply twisting the ends together or using a standard junction connector will not work. The light carrying your data must pass through the splice completely unobstructed without refraction or signal attenuation. This requires micrometer level precision.

How a Damaged Fiber Optic Cable Is Repaired

When a fiber cable is damaged, simply patching up the point of the break is rarely enough. The process requires specialized equipment and several precise steps:

Troubleshooting and location measurement: First, the distance is measured with an optical time domain reflectometer (OTDR) to pinpoint the break to within a meter.
Exposing and installing splice boxes: The damaged section is dug up and stripped back. Often, a new piece of fiber cable must be spliced in using two splice boxes if the cable has become too short or stretched.
Precision cleaning and cleaving: The glass core is cleaned with pure alcohol and cleaved with micrometer precision to ensure a perfectly flat cut.
Fusion splicing: The cable ends are placed into an advanced fusion splicer. The machine automatically aligns the two glass fibers using cameras and fuses them together with an electric arc.
Protection and testing: The splice is fitted with a heat shrink sleeve and retested to ensure signal attenuation is within approved limits.

Why Repairing Fiber Costs More Than Regular Electrical Lines.

Many are surprised by the cost of repairing a fiber cable. There are three main reasons for the price:

The equipment: A professional fusion splicer with cleaver, measurement tools, and OTDR equipment costs between 40,000 and 60,000 SEK, compared to standard electrical tools. The equipment also requires regular calibration and servicing.
Specialized knowledge and training: Splicing fiber requires specialized training and extensive experience. The required precision allows no room for error, as the smallest dust particle or uneven cut will kill the light signal, forcing the work to be redone.
Time and materials: It often requires time consuming preparation with stripping, splicing in clean environments, and mounting moisture proof splice boxes in the ground.

How to Avoid Digging Through Fiber in the Garden.

Because network operator maps rarely show the exact location of the fiber cable on your private property, manual searching is necessary. A good tip is to locate where the fiber cable enters the building facade or foundation. Then dig carefully by hand with a shovel outwards from the house at a shallow depth until you find the cable. Once you know the cable's direction and depth, you can take extra care in that area for the remainder of your project.