BSI Standards PublicationOptical fibre cables Part 5-10: Family specification — Outdoor microduct optical fibre cables, microducts and protected microducts for installation by blowing...
Construction
In addition to the construction requirements of IEC 60794-5, where applicable, the following considerations apply to outdoor microduct optical fibre cables and their corresponding microducts and protected microducts
The products specified are engineered for a minimum operational lifespan of 20 years Microduct optical fibre cables are intended for installation in microducts or protected microducts, with compatible types outlined in this standard These cables are specifically optimized for both installation and long-term performance within these microduct systems.
Microduct optical fibre cables can be installed or removed by blowing during their operational lifetime, provided certain conditions are met These conditions include avoiding multiple installation or removal operations that compromise the products, ensuring microducts are free from sediment, debris, or foreign matter due to proper maintenance, and preventing damage from external factors such as digging or earth upheavals.
In such cases, the affected section of microduct shall be cleared or repaired, or products replaced prior to any microduct cable installations
The microduct fitness should be verified with dimensional clearance and static pressure testing of the microduct route
The materials in the microduct optical fibre cable, microduct or protected microduct shall not present a health hazard within its intended use
Microduct optical fibre cables are designed for installation by blowing into microducts, although they may not be explicitly covered by specifications like IEC 60794-2, IEC 60794-3, or IEC 60794-4 While these cables can comply with various industry standards, they tend to be less mechanically robust than traditional outdoor optical fibre cables Consequently, it is essential to employ appropriate installation and handling practices to avoid damage, as improper methods could impair optical performance and shorten the product's lifespan.
A microduct is a small, flexible, and lightweight tube, typically with an outer diameter of less than 16 mm, designed for the installation of microduct cables While microduct cables offer greater mechanical robustness compared to traditional cables, they depend more heavily on microducts, protected microducts, or suitable closures for mechanical protection Consequently, it is essential for a microduct to satisfy realistic impact, compression, and bending requirements for its intended application, and a protected microduct may be necessary.
Microducts must withstand the pressure differences required for installation via blowing and should maintain a circular, uniform cross-section along their entire length The inner surface should feature a low coefficient of friction, with specified inner and outer diameters Additionally, suppliers may offer a special lining or lubricating coating on the interior to facilitate installation, provided that these layers do not diminish the specified inside diameter of the microduct.
Microducts are designed for safe installation within ducts or as part of a protected microduct system It is essential to ensure that each microduct can be easily identified along its entire length, and any colors used must comply with IEC 60304 standards.
Outdoor microducts that are not in use must be sealed at both ends to prevent moisture, debris, insects, and other contaminants that could interfere with cable installation Additionally, these microducts should be tested for obstructions before they are utilized.
A protected microduct consists of one or more microducts encased in a protective sheath or a larger duct, ensuring compliance with Clause 7 This design offers enhanced crush and impact protection compared to standalone microducts, which is essential for certain operating environments or installation methods The protective sheath may feature an integrated armouring layer or a thicker outer sheath, and it is crucial that each microduct remains identifiable along its entire length Additionally, any colors used must adhere to IEC 60304 standards.
Microduct fittings are essential components for aligning, connecting, and sealing junctions between microduct sections or connecting microduct to hardware They enable the connection of multiple microducts in series for extended installation distances or in a branch configuration with multiple output termini for a single input This flexibility is particularly beneficial in campus local area networks (LANs) and fibre-to-the-premises (FTTP) applications, allowing for easy adjustments to the optical distribution system.
Fittings must be suitable for the construction of microducts, and their mechanical and environmental performance should be tested in conjunction with ducting sections to guarantee compatibility and functionality It is essential for customers and suppliers to agree on the specific physical and material characteristics of the fittings used.
Microduct fittings must withstand the pressure differences required for the installation of microduct cables through blowing They should facilitate a seamless transition of microduct cables between consecutive sections or between microducts and hardware, while being designed and installed to avoid jamming at splice, branch, or other connection points under maximum installation pressures.
Microduct sections can be welded or secured along the same longitudinal axis without mechanical fittings, provided that these junctions adhere to the same mechanical and dimensional standards as joints created with mechanical fittings.
Translucent or transparent materials may be used to support the identification of populated microducts, and for troubleshooting installation related issues
Microduct hardware encompasses the housings and closures essential for terminating microduct cables, including splicing and connectorization These cables typically align with traditional outdoor fiber optic cable hardware, eliminating the need for specific microduct hardware requirements In certain scenarios, utilizing hardware compatible with microducts is advisable to establish a sealed microduct cabling system, such as when empty microducts are pre-installed to facilitate future cable placement.
Optical fibres
There shall be no fibre splice in a delivered length unless otherwise agreed by customer and supplier
It shall be possible to identify each individual fibre throughout the length of the microduct cable
The transmission performance shall be in accordance with Annex D.
Installation performance tests
A test route is essential for assessing the field performance of microduct cables, microducts, and protected microducts, as mutually agreed upon by the customer and supplier It is crucial to monitor ambient conditions, as they can influence installation performance Alternatively, the supplier may offer performance data derived from a designated test route, conducted under specific ambient conditions and installation methods.
Verifying that a microduct cable or microduct can be installed using a blown installation technique is critical Any installation performance requirement shall be agreed upon between customer and supplier
The tests that are applicable for installation performance are given in Table 1
Table 1 – Tests applicable for installation performance
Characteristics Family requirements Test methods Remarks
General requirements Agreement between customer and supplier
Route verification test Agreement between customer and supplier IEC 60794-1-21,
Method E23 Installation test Agreement between customer and supplier IEC 60794-1-21,
Mechanical and environmental tests
This article outlines the performance specifications for microduct cables, microducts, and protected microducts, taking into account the anticipated operating conditions and mechanical loads experienced during installation.
Tests applicable
The tests that are applicable for mechanical and environmental performance are given in Table 2
Table 2 – Tests applicable for mechanical and environmental performance of microduct cable
Characteristics Family requirements Test methods Remarks
Method F9 Fibre ribbons (if used)
Method E5B Separability of individual fibres from ribbon 5.13 IEC 60794-1-23,
Tensile performance
Under short-term tensile load, the fiber strain must not exceed 60% of the fiber proof strain Upon load removal, there should be no change in attenuation Additional criteria may be established through agreement between the customer and supplier.
Under visual examination without magnification there shall be no damage to the sheath or to the cable elements b) Test conditions
Length under tension: Not less than 50 m Shorter lengths may be used by agreement between customer and supplier, taking into account the measurement accuracy and end effects
Fibre length: Finished cable length
Diameter of test pulleys: Not less than the minimum loaded bending diameter specified for the microduct optical fibre cable
Crush
After the short-term load is removed, attenuation should remain unchanged Visual inspection must show no damage to the microduct cable, and any imprint from the plate or mandrel is not classified as mechanical damage.
Impact
Visual inspection without magnification should reveal no damage to the sheath or cable elements, and any imprint from the striking surface on the sheath is not classified as mechanical damage.
The residual increase in attenuation shall be