Customer Overview

A leading European telecom and datacom network manufacturer, delivers end-to-end indoor FTTH and FTTR connectivity across France, the UK, and neighboring markets serving high-rise residential and commercial buildings at every stage of the fiber value chain. To scale their riser and MDU deployments, they needed a compact, CPR-certified micro cable built to Europe’s strictest fire safety and optical standards. They partnered with HFCL to engineer it.

Overview

Europe’s indoor fiber market is surging, driven by the EU’s Digital Decade 2030 gigabit targets. The global FTTH market is growing at a CAGR of 12.4% through 2030, with Europe’s fiber optics segment expanding at 4.3% CAGR and FTTR accelerating at 20%+ CAGR globally. HFCL partnered with a leading European infrastructure specialist to develop a Building Micro Cable in 4F, 12F, and 24F variants, achieving Euroclass Cca s1a d0 a1 CPR certification and full IEC compliance for high-density indoor riser and FTTR deployments, with more than 500km successfully deployed.

Highlights

  • • CPR Certified – Euroclass Cca s1a d0 a1
  • • Available in 4F, 12F, and 24F fiber counts
  • • Compliant with IEC 60793 and IEC 60794 standards
  • • Compact, flexible design for tight riser pathways
  • • LSZH sheath with enhanced fire-retardant formulation
  • • 200μm fiber coating in the 24F variant for improved space efficiency (~36% reduction in packing density compared to 250μm)

Challenges Faced

1. Temperature Cycle Instability

The initial cable design exhibited higher-than-acceptable sheath shrinkage after temperature cycling, exceeding industry norms which typically demand no more than 5%. This instability created mechanical stress on the optical fibers, posing risks to long-term signal performance, with potential attenuation degradation of up to 2.35 dB/km. Achieving dimensional stability while maintaining a compact micro cable structure within the sub-2.65, 2.65, and 2.8mm outer diameter envelope proved to be a complex material and process engineering challenge

2. Dimensional Constraints in the 24F Variant

The 24F high-density variant presented a fundamental geometric conflict: increasing sheath thickness for fire performance and mechanical protection directly reduced the available internal space for fiber accommodation, all within a fixed, market-specified outer diameter. Standard 250μm fiber coatings left insufficient room to meet both structural and fire-class requirements at the same time

3. Fire Retardancy Compliance (Euroclass Cca)

Achieving Euroclass Cca s1a d0 a1 which governs flame spread, smoke density, flaming droplets, and acidity required a materially superior LSZH formulation. The challenge was to enhance fire-retardant performance without increasing the overall cable diameter, which was already operating at minimum tolerances.

HFCL's Approach to
These Challenges

1. Material and Process Optimization for Thermal Stability

Four different LSZH compounds were evaluated through controlled production trials to analyze thermal contraction behavior across a temperature range of -20°C to 60°C, as per IEC-60794-1-22. In parallel, extrusion tooling was redesigned to improve material flow uniformity and reduce residual internal stress within the sheath. Through this iterative approach spanning one year, shrinkage was reduced by 75%, bringing dimensional change well within the industry threshold. The cable successfully qualified under IEC temperature cycling conditions, with zero measurable attenuation degradation post-cycling, recording less than 0.05 dB/km change

3. Enhanced Fire Performance via LSZH Reformulation

To achieve Euroclass Cca s1a d0 a1 within the original outer diameter envelope, HFCL's materials team reformulated the LSZH sheath compound by optimizing material volume distribution within the existing diameter limits to improve flame resistance under vertical flame testing. The reformulated sheath achieved full Cca s1a d0 a1 classification, covering low flame spread, minimal smoke generation (s1a), zero flaming droplets (d0), and low acidity (a1) all critical requirements for high-occupancy residential and commercial building environments.

2. Structural Redesign for the 24F Variant

To resolve the geometry conflict in the 24F configuration, HFCL's engineering team redesigned the cable's internal architecture. The key innovation was reducing the fiber coating diameter from 250μm to 200μm. This change freed up approximately 54% of radial space, allowing the sheath thickness to be increased by 0.07mm without exceeding the specified outer diameter. The 24F cable passed all mechanical, dimensional, and CPR fire-class tests following the redesign.

Success Metrics

Certified for Advanced Fire
Safety Compliance

Achieved Euroclass Cca s1a d0 a1 certification across all cable variants. Delivers low flame spread, minimal smoke, and zero flaming droplets

75% Improvement in Thermal
Stability

Shrinkage reduced significantly through multi-stage LSZH compound optimization. Ensures dimensional consistency across wide temperature variations.

Superior Optical Performance
Stability

Attenuation variation maintained below 0.02 dB/km after thermal cycling. Exceeds performance targets, ensuring reliable signal transmission.

Enhanced Fiber Density
Efficiency

Achieved 36% reduction in packing density versus 250μm designs. Enables compact, high-capacity cable configurations

Validated Through Large-Scale
Deployments

Over 500 km successfully deployed across France, the UK, and nearby regions. Proves consistent performance in realworld network conditions.

Compact Design with High
Flexibility

Optimized cable OD (2.65 2.8 mm) with a bending radius of 10D. Supports easy installation in tight and high-density environments.

Conclusion

This Building Micro Cable demonstrates HFCL's ability to solve complex, interrelated engineering challenges thermal stability, fire compliance, and tight geometric constraints through rigorous material science, iterative structural redesign, and disciplined testing. The result is a CPR-certified, high-density indoor micro cable that improves safety, accelerates installation, and delivers long-term optical reliability in Europe's rapidly scaling FTTH and FTTR networks.

As FTTR deployment accelerates toward the EU's 2030 gigabit goals targeting gigabit connectivity for all European households HFCL continues to partner with leading European operators and infrastructure specialists to deliver fiber solutions that are safer, more compact, and fully aligned with evolving regulatory standards.

About Us

HFCL is a leading technology company specializing in creating digital networks for telcos, enterprises, and governments. Over the years, HFCL has emerged as a trusted partner offering sustainable high-tech solutions with a commitment to providing the latest technology products to its customers. Our strong R&D expertise coupled with our global system integration services and decades of experience in fiber optics enable us to deliver innovative digital network solutions required for the most advanced networks. The company’s in-house R&D Centres located at Gurgaon and Bengaluru along with invested R&D houses and other R&D collaborators at different locations in India and abroad, innovate a futuristic range of technology products and solutions. HFCL has developed capabilities to provide premium quality Optical Fiber and Optical Fiber Cables, state-of-the-art telecom products including 5G Radio Access Network (RAN) products, 5G Transport Products, Wi-Fi Systems (Wi-Fi 6, Wi-Fi 7), Unlicensed Band Radios, Switches, Routers and Software Defined Radios. The company has state-of-the-art Optical Fiber and Optical Fiber Cable manufacturing plants in Hyderabad, an Optical Fiber Cable manufacturing plant in Goa, and its subsidiary HTL Limited in Chennai. We are a partner of choice for our customers across India, Europe, Asia Pacific, the Middle East, Africa, and the USA. Our commitment to quality and environmental sustainability inspires us to innovate solutions for the ever-evolving customer needs.

Contact Us
About HFCL

HFCL is a leading technology company specializing in creating digital networks for telcos, enterprises, and governments. Over the years, HFCL has emerged as a trusted partner offering sustainable high-tech solutions with a commitment to providing the latest technology products to its customers. Our strong R&D expertise coupled with our global system integration services and decades of experience in fiber optics enable us to deliver innovative digital network solutions required for the most advanced networks.

The company’s in-house R&D Centres located at Gurgaon and Bengaluru along with invested R&D houses and other R&D collaborators at different locations in India and abroad, innovate a futuristic range of technology products and solutions. HFCL has developed capabilities to provide premium quality Optical Fiber and Optical Fiber Cables, state-of-the-art telecom products including 5G Radio Access Network (RAN) products, 5G Transport Products, Wi-Fi Systems (Wi-Fi 6, Wi-Fi 7), Unlicensed Band Radios, Switches, Routers and Software Defined Radios.

The company has state-of-the-art Optical Fiber and Optical Fiber Cable manufacturing plants in Hyderabad, an Optical Fiber Cable manufacturing plant in Goa, and its subsidiary HTL Limited in Chennai.

We are a partner of choice for our customers across India, Europe, Asia Pacific, the Middle East, Africa, and the USA. Our commitment to quality and environmental sustainability inspires us to innovate solutions for the ever-evolving customer needs.