Common Causes of Fiber‑Optic Cable Interruptions and Repair Guidelines

On the afternoon of March 23, users reported login failures for several Tencent applications, including QQ Music and Honor of Kings. The official account confirmed that from 14:30 the games experienced crashes, missing matches, and inability to watch streams. Tencent later announced that a massive fiber‑optic line failure caused by a local Shanghai ISP’s network fluctuation was the root cause, and that emergency repairs and disaster‑recovery measures were underway.

Fiber cables, though thin, carry countless communication services and are the backbone of modern connectivity. When a fiber line breaks, maintenance crews must respond immediately, regardless of weather or time of day.

Eight common causes of fiber‑cable interruptions and repair considerations:

1. Construction cuts – Excavation for roads, drainage, municipal landscaping, or gas pipelines often accidentally sever fibers. Technicians should use an OTDR for bidirectional testing, focus on the 1‑km area around the fault, and inspect poles, ducts, and bends to prevent additional damage.

2. Vehicle collisions – Vehicles striking poles can break cables. Upon arrival, crews must set up warning signs, control traffic, and perform OTDR tests on both sides of the fault. Temporary supports (e.g., poles or ladders) should be used to lift the cable before repair.

3. Fires – Fire‑induced faults usually affect individual fibers rather than the whole cable. After extinguishing the fire, technicians should identify and cut all damaged sections before splicing, marking both ends of the burnt area to avoid re‑work.

4. Pole collisions – Traffic work can knock down poles, severing fibers. Safety zones and traffic control are essential, followed by OTDR testing and prompt replacement of the broken pole with protective paint.

5. Theft or intentional damage – Criminals may cut or sabotage cables, especially in remote areas. After bidirectional OTDR testing, crews should inspect surrounding sections, replace the cut segment within ~100 m, and report the incident to authorities.

6. Animal bites or projectile damage – Rare events such as dog bites, rodent gnawing, bird pecking, or gunshots can cause single‑fiber faults. Routine inspections and protective measures reduce risk; initial response often involves jumping the affected core before locating the exact break.

7. Fiber aging and natural breakage – Over time, glass fibers fatigue and may fracture, especially after 15 years of service. Aging faults are typically addressed by core‑jump restoration followed by replacement or splicing of the aging segment.

8. Natural disasters – Large‑scale events can disrupt extensive fiber networks. Safety comes first; crews should use radios or multi‑carrier phones to maintain communication while performing the fastest possible repairs.

Protecting fiber infrastructure is vital: avoid moving or damaging cables, coordinate with telecom authorities before nearby construction, and always prioritize safety during emergency repairs.