Optical Fiber Cable Specifications and Fibre-Count Guide
Optical Fiber Cable Specifications and Fibre-Count Guide
Posted on July 07, 2026This guide sets out the technical parameters to define when specifying optical fiber cable. For how these map to physical cable families, see types of optical fiber cable.
Fibre count by construction
| Construction | Fibre count | Typical use |
| Uni-tube | Up to 12 fibres | Access / distribution |
| Multi-tube (loose tube) | Up to 144 fibres | Backbone / trunk |
Core construction specifications
• Central strength member — non-metallic FRP rod that the loose tubes are S-Z stranded around, giving tensile strength without metal.
• Loose tubes — house the fibres and are filled with thixotropic jelly for water-blocking; dry-core construction is available as an option.
• Pulling strength — glass-yarn or aramid-yarn reinforcement can be added for axial pulling/blowing strength in ducts.
Jacketing specifications
| Jacket | When to specify |
| HDPE | General outdoor and duct routes |
| LSZH | Indoor, tunnels, confined spaces (low smoke, zero halogen) |
| PVC | Cost-sensitive indoor/semi-protected runs |
| PA-12 | Demanding mechanical/chemical environments |
Fibre grade
Specify the fibre standard alongside the cable: single-mode G.652 for standard long-haul, or bend-insensitive G.657 for tight-routing access networks. Confirm attenuation and dispersion limits with the manufacturer.
Installation suitability
Confirm the design is rated for the intended method — blowing in HDPE ducts/PVC pipes, pulling into service ducts, aerial stringing, or direct burial. Application areas include backbone routes, telecom and data trunk, secondary distribution and aerial CATV. For background, see the comprehensive OFC guide, and to select a supplier, factors in choosing an OFC manufacturer.
Frequently Asked Questions
What is the maximum fibre count?
Multi-tube (loose-tube) designs reach up to 144 fibres; uni-tube designs hold up to 12 fibres.
What is the central strength member made of?
A non-metallic FRP (fibre-reinforced plastic) rod, around which the loose tubes are S-Z stranded.
What jacket should I choose for indoor use?
LSZH (low-smoke zero-halogen) is preferred indoors and in tunnels for fire-safety; HDPE is standard for outdoor and duct routes.
What is dry-core construction?
A water-blocking design that replaces jelly filling with dry water-swellable elements, making the cable cleaner to prepare during splicing.