Horizontal Fiber Optic Splice Closure

A horizontal fiber optic splice closure (also called an inline closure, in-line enclosure, or horizontal joint box) is a sealed protective housing for fiber fusion splices where cables enter from both ends of the enclosure. This is the key distinction from dome/vertical closures - horizontal closures allow cable to pass straight through the splice point, making them ideal for continuous cable routes.
The GL-H series is a MADIDI-type horizontal closure with PP+GF reinforced housing, IP68 waterproofing, and a tool-free re-entry mechanism - available in 144-core and 288-core configurations for FTTH, FTTB, FTTC, and backbone applications.

Horizontal / inline closure (GL-H series):​ Cables enter from opposite ends. Used for mid-span splicing where a continuous cable route passes through the closure. Common in backbone trunk runs, long-haul cable routes, and aerial spans.
Dome / vertical closure (GL-5601):​ All cables enter from one end. Used for branch-and-distribution topologies - one feeder cable in, multiple drop cables out. Common at FTTH distribution points, access nodes, and pole-mounted splitter enclosures.
The practical rule: if a cable runs continuously through the splice point, use horizontal. If cables terminate and branch at the splice point, use dome. Mixed-topology sites sometimes use both.

MADIDI is an industry descriptor for a closure design philosophy: Modular, Aerial-mount-compatible, Direct-burial-rated, In-line Design, IP-rated. It describes closures engineered for: (1) tool-free opening and closing, (2) deployment across multiple installation environments without changing the core product, and (3) reliable IP-rated sealing that survives re-entry cycles.
In practical terms, a MADIDI-type closure means a field technician can re-enter the closure for maintenance, fiber additions, or fault repair without carrying specialty equipment or consumable sealing kits - which reduces truck-roll costs on distributed networks.

Yes. The GL-H series is rated for direct burial as well as aerial, duct/pipeline, wall mount, and manhole installations - all supported by the same product without configuration changes. The IP68 rating handles the soil moisture and hydrostatic pressure typical of direct burial at depths up to 1 meter.
For direct burial specifically: ensure the cable entry ports are correctly compressed against the grommet seals before burial, use a UV-stable identification marker at the burial location, and record GPS coordinates of all buried joints for future maintenance access.

PP+GF (Glass-fiber reinforced polypropylene)​ - higher tensile strength, better UV resistance, better performance in extreme temperature cycling, and superior resistance to acid, alkali, and salt corrosion. The glass fiber reinforcement reduces thermal expansion/contraction compared to unfilled plastics. The GL-H series uses PP+GF.
ABS (Acrylonitrile Butadiene Styrene)​ - lower cost, easier to mold, adequate for moderate environmental conditions. Commonly used in indoor or mild-climate outdoor applications. More prone to UV degradation and embrittlement in prolonged sunlight or high-temperature environments.
For outdoor backbone and backbone-adjacent deployments with 15–25 year expected service life, PP+GF is the recommended material choice. ABS is acceptable for sheltered or indoor-adjacent installations.

Standard port seals accept cables with outer jacket diameters of Φ8 mm to Φ18 mm. This covers most standard loose-tube backbone cables, aerial self-supporting cables, and armoured duct cables in this capacity range. For non-standard cable sizes - large-OD armoured cables over 20mm, or flat drop cables - custom port grommet kits are available; specify the cable outer diameter in your inquiry.

Yes. The GL-H series is suitable for 5G fronthaul and backhaul cable routes in the following configurations: (1) mid-span splice protection on aerial fronthaul cables connecting BBU pools to RRU/AAU equipment, (2) underground duct-route splice nodes on fiber backhaul from cell sites to aggregation rings, and (3) backbone trunk splice nodes on the core ring feeding multiple cell site spurs.
The −40°C to +85°C operating temperature accommodates rooftop, antenna-tower-adjacent, and ground-level outdoor cabinet installations in tropical and arctic markets. IP68 handles rain exposure without additional weatherproofing.

Standard MOQ is 50 units​ for production orders. Free samples (1–2 units) are available for qualified project evaluations - typically shipped within 3–5 business days. Production lead time is 10 working days for standard configurations; OEM/ODM (custom color, branding, port configuration) requires additional tooling lead time confirmed at order. Contact us with your project specification for a direct quotation.