Protecting Fiber Optic Splices: The Role of Splice Closures

As fiber optic networks expand to meet the growing demand for high-speed internet and telecommunications, properly protecting the fragile splices between fiber cables becomes increasingly important. Fiber optic splice closures play a vital role in safeguarding these connections from environmental hazards and damage.

What is a Fiber Optic Splice Closure?

A fiber optic splice closure is a protective enclosure designed to house and shield cable splices. It is installed along the cable route, often mounted on aerial, underground, or buried fiber optic cables. The closure provides an isolated, controlled environment that prevents moisture, dirt, and other contaminants from reaching the splice. It also absorbs cable tension and prevents the transmission of physical shocks and vibrations to the splice.

Splice closures are typically dome-shaped or cylindrical and made of durable, weather-resistant materials like composite polymer or aluminum. The size and specific design varies based on the application. Features like silicone gel sealing, rubber gaskets, and cable entry ports help block moisture and maintain an airtight seal. The closure is filled with a gel or fluid compound that further cushions and waterproofs the splice.

Why are Splice Closures Necessary?

Without adequate protection, splices between fiber optic cables are prone to damage and signal loss. Fiber optics transmit data via pulses of light through extremely fine glass fibers. If the fibers are bent too far or hit with force, they can fracture and break. The microscopic splices that join fiber segments are especially fragile.

Splice closures shield these vital splice points from:

• Tension or twisting of the cable that overstresses the fibers

• Vibration and shocks such as nearby construction work

• Rodents, birds, or insects chewing through cables

• Accumulation of moisture and dirt that degrades the splice

• Extreme temperatures that cause sealants to expand and contract

Proper installation of splice closures reduces the risk of connection failure. They are indispensable for maintaining network reliability and performance.

Applications of Fiber Optic Splice Closures

Splice closures allow new fiber optic cables to be spliced into existing lines during network expansions. They are also placed:

• Wherever fiber cables are rerouted or branched

• At specific distance intervals along cable routes

• On both sides of obstacles like rivers and highways that cables must pass under

• At sites where cables transition from underground to aerial installations

Closures may be designed for indoor or outdoor use. They are sized to accommodate anywhere from one to several hundred fiber splices in a single enclosure. Different types are suited for aerial, direct-buried, handhole, or manhole installation.

Key Features and Components

Modern splice closures utilize several key features and components to keep splices secure:

• Sealing gels - The thixotropic gel fills the closure to prevent moisture ingress. It cushions splices from physical disturbance.

• Organizing trays - The fiber splices rest in trays that separate and organize the cables, buffer tubes, and individual fibers.

• Cable entry ports - Rubber grommets seal around the cables where they enter the closure.

• Mounting brackets - Underground closures attach to buried cables via strength members. Aerial closures mount to messenger wires or the cable strand.

• Access door - Technicians can reopen the closure to access splices through a removable door or dome section.

Proper Installation Techniques

Installing fiber optic splice closures requires care to ensure long-term reliability:

• Prepare cables properly - Remove jacket materials, clean fibers, install connectors and splices.

• Insert cables evenly - Avoid overstressing the fibers when inserting into ports.

• Seal entry ports - Tighten grommets and apply sealant for a watertight seal.

• Check internal seals - Inspect o-rings and gaskets, repair defects.

• Fill with gel - Pump filling gel until all air bubbles are gone.

• Secure to cable - Attach strength members firmly to prevent stresses on splice.

• Ground wires - Connect ground lugs to prevent electrical damage.

Regular inspection and maintenance is also advised. Technicians should re-enter closures occasionally to check seals and remove any moisture accumulation.

The Future of Fiber Optic Splice Closures

Advancements in fiber optic splicing continue to minimize size while improving ease of access and re-entry. Splicing speeds have increased dramatically. New heat-shrink splicing devices can join fibers in under 2 minutes with no need for protective gel or housing. This may eventually eliminate the need for splice closures in some applications.

However, splice closures continue to serve a vital role in shielding connections from environmental hazards. They remain an essential component in expanding and upgrading fiber optic networks. With global data demands growing, fiber optic splice closures will continue protecting these critical backbone links well into the future.