Unique colour-coded 180µm fibre cabling


Prysmian Group: producing the only colour-coded 180µm fibre cabling on the market

An optical cable may contain up to 6,912 fibres and each individual fibre needs to be colour-coded. After all, if there’s more than one fibre in a cable, you’ll need to be able to tell the fibres apart at both ends of the cable to connect them correctly. Without colour-coding, this would be impossible – that’s why it is an essential part of cable management.

Fibre colour-coding enables installers to identify fibres more easily, quickly, and effectively. This, in turn, makes splicing and maintenance easier and helps speed up installations. As a result, fewer installation errors occur. The international practice for colouring fibres is to use a set of 12 colours (or more, in some cases using additional ring marks with each colour).

Increasing the fibre density in cables, by reducing the diameter of individual fibres, is essential to meeting current rollout demand. More capacity needs to be introduced in ever-more congested ducts and confined spaces. This also helps reduce the amount of required civil works and related costs, packaging and transport costs, and carbon emissions during network construction. It is, however, essential that reduced fibre diameter does not compromise fibre performance and ensures fibre is fully compatible with legacy networks and can be spliced for standard diameter fibres.

The diameter reduction has significant consequences for the permissible thickness of the colour coating. A standard fibre is made up of a glass core and cladding of a diameter of 125µm surrounded by protective plastic primary coating and secondary clear coating. Finally, a layer of UV cured coloured ink is applied to reach the final - coloured - fibre diameter. This ink layer is usually around 10µm in thickness and when there are large numbers of fibres in a cable, the thickness of each colour coat adds up. The challenge is to apply the thinnest coating without sacrificing robustness or flexibility. As a result, cables advertised as 180 µm might actually turn out to be 190 µm once colouring has been added. In a bundle containing hundreds or thousands of fibres, that makes significant difference to overall thickness.

Prysmian’s solution is to add a secondary layer of coating, which already contains coloured pigments, which avoids using an additional layer of ink. Our ColorLock-XS fibre coating system consists of two layers of specially engineered acrylate coatings. The inner primary coating layer next to the fibre is made of a low modulus material, which provides a soft cushion to protect the surface of the fibre from any micro-bending forces. The outer primary layer, made up of a higher modulus material, provides tough outer protection. This allows the fibre to be flexible while contributing both mechanical and environmental protection.

The coatings applied during fibre drawing, immediately bonds to the pristine glass, and creates a barrier against any outside contaminants or effects of harsh environments. The coating system protects the glass surface from moisture and other environmental effects, which can impact the fibre’s strength and long-term reliability. Thanks to this proprietary technology, Prysmian is currently the only manufacturer producing a reduced-diameter 180µm optical fibre that is already colour coded and offers the greatest assurance of long-term strength, performance, and reliability. Other manufacturers may state that they have 180µm or 190µm fibers available, but the dimensions quoted are for natural fibers, which become larger when the UV cured colour ink layer is added.