Armoured or unarmoured fibre cable: how to choose

Begin with the route

The route is the starting point for cable selection. Is the cable installed in a duct, inside a building, or along another protected route? What pulling, crushing, bending and environmental conditions will it encounter? Armoured and unarmoured are construction descriptions, not complete installation specifications.

What steel-tape armour adds

Nova's listed armoured optical fibre constructions use corrugated ECCS steel tape. The published armour thickness is 0.155 mm nominal. Armour forms a metallic protective layer around the cable core; it does not replace the need to check the cable's rated tensile load, crush resistance, bend radius and installation requirements.

Metallic components also need to be considered in the project's bonding and earthing design. Confirm the applicable installation requirements with the responsible designer rather than treating the cable name as an installation instruction.

Glass-yarn reinforcement without armour

Unarmoured does not mean that a cable has no strength members. Nova's single-tube unarmoured cable lists glass yarn with or without reinforcement, while the multitube unarmoured construction lists IGFR glass-yarn reinforcement and no armour. Glass yarn and steel tape play different roles in the construction and should not be treated as interchangeable layers.

Ducts and other protected routes may permit an unarmoured construction when the mechanical and environmental requirements are met. The final choice depends on the project specification and the protection provided by the route.

Compare the listed constructions

• Single-tube unarmoured: 2F to 12F, with a listed outer diameter of 5.5–6.5 mm.
• Multitube armoured, single sheath: a listed construction up to 12F with corrugated ECCS armour.
• Multitube armoured: up to 288F, using 9 inner and 15 outer tubes.
• Multitube unarmoured: up to 48F, using 6 tubes of 8 fibres.

Specify the whole cable

Confirm fibre count and type, construction, sheath, drum lengths, marking, standards and delivery requirements. Match the mechanical values to the planned installation and check the current specification before ordering. Neither armour nor a high fibre count is a substitute for route-specific engineering.