Repairing a Damaged Submarine Cable: How MainOne Was Put Back in Service

Internet Network

By Jayne MillerAug 8, 2017


When the MainOne Submarine Fiber Cable System went down in mid-June, what were the steps taken to restore service on July 3?

How are damaged submarine cables repaired?

Using MainOne as an example, in this scenario, a fault occurred about 3,000 kilometers south of Portugal, where the cable lies in 3,400 meters of water. (The cause? An underwater landslide.)

Here’s how a technical team managed the fault.

According to the technical report issued by MainOne following the cable restoration, the first step was to call on the organization’s membership in the Atlantic Cable Maintenance and Repair Agreement (ACMA).

ACMA is a non-profit subsea maintenance agreement with 59 members. These members include companies responsible for the operations and maintenance of undersea communications and power cables in the Atlantic, North Sea, and Southeastern Pacific Ocean. With the help of this organization, a French cable ship was sent to repair the damaged cable.

By the next morning, the French vessel was headed to Portland, United Kingdom to pick up supplies. This included backup cables, a spare repeater, and jointing materials.

Next stop? The repair location. Eight days after leaving France, the vessel arrived on June 27.

Once on the scene, the cable was grappled and brought on board. The team surveyed the damaged section and game-planned how to repair. The engineers ultimately replaced the damaged section with the new cable section brought from Portland, which was spliced into the broken ends.

Following plenty of tests, molds were applied to protect the fibers before being placed back into the water. The repair passed the even more testing and the cable was back in business during the early hours of July 3.

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