Dome Type Splice Closures VS Horizontal Splice Enclosures

In the rapidly evolving world of fiber optic infrastructure, splice closures play a pivotal role in protecting fiber splices from environmental hazards while ensuring long-term network reliability. As FTTH, 5G backhaul, and data center expansions accelerate into 2025, network planners and installers frequently face a key decision: Dome Type Splice Closures o horizontal splicing enclosures?

Also known as dome closure, dome type closure, dome splice closure, fiber dome closure, dome fiber optic splice closure, or horizontal fiber optic splice closure y horizontal junction closure / horizontal enclosure, these two designs dominate the market.

This exhaustive guide compares every aspect of Dome Type Splice Closures versus horizontal splicing enclosures: design principles, capacity, sealing performance, installation ease, applications, cost, durability, and 2025 innovations.

Whether you are a telecom engineer, procurement specialist, or contractor managing large-scale rollouts, this article — written by Dekam Fiber, a leading manufacturer of both dome and horizontal closures — will help you make the optimal choice for your project.

1. Understanding the Two Main Types of Fiber Optic Splice Closures

Fiber optic splice closures are protective housings that seal and organize optical fiber splices, providing mechanical protection, environmental sealing, and easy re-entry for maintenance.

1.1 Dome Type Splice Closures

Dome Type Splice Closures (commonly called dome closure, dome type closure, or dome splice closure) feature a vertical, cylindrical design with a domed end cap that seals via a clamp and O-ring system.

Key characteristics:

• Vertical orientation
• Single end-entry (cables enter from bottom)
• Heat-shrink or mechanical sealing for ports
• Typically pole, aerial, or manhole mounted

Popular models: fiber dome closure, dome fiber optic splice closure — capacities from 24 to 576 fibers.

1.2 Horizontal Splicing Enclosures

Horizontal splicing enclosures (also known as horizontal fiber optic splice closure, horizontal junction closure, or simply horizontal enclosure) have an inline, “clam-shell” design that opens lengthwise.

Key characteristics:

• Horizontal orientation
• Multiple cable entries on both ends
• Gasket sealing with bolts or clamps
• Primarily underground, direct-buried, or wall-mounted

These two fundamentally different designs serve overlapping but distinct needs.

2. Design and Mechanical Structure Comparison

2.1 Dome Type Splice Closures

• Shape: Tall, cylindrical with rounded dome top
• Entry: Single end (bottom) with 4–8 oval/round ports
• Caza de focas: Clamp band + O-ring (heat-shrink sleeves on cables)
• Internal Tray: Stacked splice trays (up to 24 trays)
• Mounting: Pole brackets, aerial hanging, manhole brackets

The dome shape distributes pressure evenly, making dome splice closure exceptionally resistant to external forces.

2.2 Horizontal Splicing Enclosures

• Shape: Long, rectangular “box”
• Entry: Multiple ports on both ends (6–12 ports total)
• Caza de focas: Perimeter gasket + bolts/latches
• Internal Tray: Side-by-side or book-style trays
• Mounting: Wall, pedestal, direct bury

The inline design of horizontal fiber optic splice closure excels at mid-span access.

Característica	Dome Type Splice Closures	Horizontal Splicing Enclosures
Shape	Vertical dome	Horizontal inline
Cable Entry	Bottom only	Both ends
Typical Capacity	48–576 fibers	24–288 fibers
Re-entry Method	Remove dome cap	Open clamshell
Pressure Resistance	Excellent (dome shape)	Good
Mid-span Access	Limited	Excellent

3. Sealing and Environmental Protection

Both types achieve IP67 rating, but design affects performance.

3.1 Dome Closure Sealing Advantages

• Single large O-ring seal
• Fewer potential leak points
• Superior compression resistance (dome shape)
• Excellent in high-water-pressure manholes

Real-world testing: fiber dome closure models withstand 10 m water head for 30 days without leakage.

3.2 Horizontal Enclosure Sealing

• Long perimeter gasket
• More bolts/clamps needed
• Vulnerable at gasket corners

However, modern horizontal junction closure designs use advanced silicone gaskets and over-center latches for reliable sealing.

Environmental Test	Dome Type Performance	Horizontal Performance
IP68 Water Immersion	Excellent	Very Good
Impact Resistance (IK10)	Excellent	Good
UV Resistance	Excellent	Excellent
Temperature Cycling (–40°C to +85°C)	Excellent	Very Good

Dome fiber optic splice closure generally wins in harsh aerial/manhole environments.

4. Capacity and Scalability

4.1 Dome Type Splice Closures

• High capacity: up to 576 fibers (24 trays × 24 splices)
• Ideal for high-fiber-count feeder cables
• Easy tray stacking

4.2 Horizontal Splicing Enclosures

• Typical max 288–360 fibers
• Better for lower-count distribution

For large FTTx nodes, Dome Type Splice Closures are preferred.

5. Installation and Re-entry Comparison

5.1 Dome Closure Installation

• Vertical mounting simplifies aerial work
• Single-end entry reduces cable bending
• Fast clamp sealing (5–10 minutes)

5.2 Horizontal Enclosure Installation

• Inline entry perfect for direct bury
• Clamshell design allows mid-span splicing
• More time-consuming bolt tightening

Horizontal fiber optic splice closure excels in underground mid-span applications.

Installation Factor	Dome Type	Horizontal
Aerial/Pole Ease	Excellent	Good
Underground Direct Bury	Good	Excellent
Mid-span Splicing	Difficult	Excellent
Re-entry Time	10–15 minutes	15–25 minutes

6. Applications and Use Cases in 2025

6.1 Where Dome Type Splice Closures Excel

• Aerial and pole-mounted FTTH distribution
• Manhole and handhole installations
• High-fiber-count feeder routes
• Harsh environments (coastal, desert)

6.2 Where Horizontal Splicing Enclosures Shine

• Direct-buried cable routes
• Mid-span access points
• Underground vault installations
• Lower-density distribution networks

7. Cost Comparison 2025

Capacity (fibers)	Dome Type Closure Price	Horizontal Enclosure Price
48–96	$25–$50	$20–$45
144–288	$60–$90	$50–$80
288–576	$90–$110	$80–$100

Dome closures have ~10–20% premium due to larger housing and sealing system.

8. Innovations and Trends 2025–2030

• Gel-free dry sealing
• Integrated splitter modules
• Smart monitoring (temperature, humidity sensors)
• Higher port counts (32-port dome)
• Sustainable materials

Conclusion: Choosing the Right Closure for Your Network

Dome Type Splice Closures offer superior sealing, higher capacity, and easier aerial installation — making them ideal for modern FTTH and 5G deployments.

Horizontal splicing enclosures remain essential for underground mid-span and direct-bury applications.

The best networks use both strategically.

Dekam Fiber manufactures industry-leading dome splice closure, fiber dome closure, dome fiber optic splice closure, and horizontal fiber optic splice closure series — all with IP67 sealing, 2-year warranty, and full customization.

Need help selecting the perfect closure for your project? Contact Dekam Fiber today for samples, pricing, or expert consultation.

Your splices deserve the best protection — choose wisely.