Why Fibre Optic Cables Fail (Outdoor and Underground Environments)
What causes fibre optic cable failure?
Fibre optic cables typically fail due to degradation of the outer jacket rather than the optical fibre itself. Specifically, ultraviolet (UV) exposure, moisture ingress, thermal ageing and biological damage such as termite activity drive this process. Over time, these factors reduce mechanical integrity and cause cracking, embrittlement and eventual failure.
What is fibre optic cable failure?
Fibre optic cable failure refers to the loss of mechanical integrity or performance of the cable system. In most cases, environmental degradation of the outer jacket causes this failure rather than damage to the optical fibre itself.
What are the main causes of fibre optic cable failure?
Fibre optic cable failure typically results from environmental stress on the cable jacket.
The main causes of fibre optic cable failure include:
- UV exposure
- moisture ingress
- thermal ageing
- termite activity
Each of these factors affects the cable jacket over time, increasing the risk of long-term failure.
These failure mechanisms primarily affect the cable jacket rather than the optical fibre itself.
How can fibre optic cable failure be prevented?
Fibre optic cable failure can be reduced by selecting durable jacket materials, using UV stabilised compounds, limiting moisture exposure and protecting against biological damage such as termites.
How does UV damage fibre optic cables?
UV radiation causes photodegradation in polymer cable jackets. This process is well documented in studies on polymer degradation due to UV exposure. As a result, the material develops surface cracking, embrittlement and reduced mechanical strength. Over time, this degradation reduces the cable’s ability to withstand handling and environmental stress in outdoor installations.
Learn more: UV Resistant Cable
How does moisture affect fibre optic cables?
Moisture exposure in underground conduit systems causes material instability, swelling and long-term degradation of cable jackets. In practice, even protected environments such as ducts and pits allow water ingress, which remains a key factor affecting long-term durability.
Moisture exposure affects polymer performance due to mechanisms such as water absorption in polymers, which can reduce long-term stability.
Learn more: PA12 Nylon in Fibre Cable
What is thermal ageing in fibre optic cables?
Thermal ageing occurs when elevated temperatures accelerate oxidative reactions within the cable jacket material. As a result, the material loses flexibility, becomes more brittle and gradually reduces mechanical performance over time.
Thermal ageing accelerates polymer oxidation and thermal degradation, which reduces flexibility and increases brittleness over time.
Learn more: Antioxidant Cable Protection
Can termites damage fibre optic cables?
In certain environments, termites can physically breach cable jackets and expose internal fibres to moisture and mechanical damage. As a result, this creates a recognised risk in rural and regional underground deployments.
Learn more: Termite Resistant Cable
Why does material selection matter in fibre optic cables?
Material selection determines how well a cable resists environmental degradation over time. In particular, the outer jacket acts as the primary barrier against UV exposure, moisture, thermal stress and biological attack. As a result, different materials perform differently under these conditions, making polymer selection a critical factor in long-term reliability.
Learn more: Nylon in Fibre Optic Cables
What is the most durable material for fibre optic cable jackets?
High-performance polymers such as PA12 (Polyamide 12) play a key role in modern fibre optic cables due to their low water absorption, dimensional stability and long-term mechanical performance in harsh environments. As a result, engineers select PA12 for applications that require durability and consistent performance over time.
Learn more: PA12 Nylon Fibre Optic Cable
How can fibre optic cable failure be prevented?
Fibre optic cable failure can be reduced by:
- selecting materials with low water absorption
- using UV stabilised cable jackets
- incorporating antioxidant protection systems
- protecting against biological damage such as termites
- ensuring proper installation practices
These factors collectively improve long-term cable durability and reliability.
Are underground fibre optic cables directly buried?
In modern network deployments, fibre optic cables are typically installed within conduit or duct systems rather than direct burial. However, these environments still expose cables to moisture, temperature variation and installation stress. As a result, material selection remains critical for long-term performance.
From Failure Mechanisms to Engineering Solutions
Understanding why fibre optic cables fail highlights the importance of combining:
- stable base materials
- engineered protection systems
- installation-aware design
Modern cable design focuses on mitigating environmental stress factors rather than reacting to failure after installation.
Applying These Principles in Real-World Networks
The engineering principles outlined above are applied in:
RapidConnect® TR-Series Fibre Optic Cable
This cable integrates:
- PA12 nylon jacket for moisture resistance
- UV stabilisation for outdoor durability
- antioxidant protection for thermal ageing
- termite deterrent additives for underground deployments
- bend-insensitive fibre for modern routing environments
Designed for conduit-based underground and outdoor networks, the TR-Series supports long-term reliability in demanding Australian conditions.
Looking for a Fibre Cable Designed to Prevent Failure?
Explore the TR-Series
Key Takeaway
Fibre optic cable failure is rarely caused by the fibre itself. It is driven by environmental degradation of the cable jacket over time.
By addressing:
- UV exposure
- moisture ingress
- thermal ageing
- biological risk
and selecting appropriate materials and stabilisation systems, long-term performance can be significantly improved.