Speed matters in fiber installs, but so does getting the details right.
Choosing the wrong microduct size or cable type can lead to delays, costly rework, and frustrated crews. And with underground fiber deployment costs up 12% in 2024, according to the Fiber Broadband Association, the margin for error is shrinking.
This guide walks through the key steps to designing a microduct system that fits your fiber, your route, and your budget. From cable sizing to duct selection, we’ll show you how to make decisions that keep your project moving forward.
Every project begins with where the microduct will be installed. Once the environment is clear, the right microduct type follows.
Building a new route? Direct bury (DB) microduct combines conduit and pathway in a single step. It’s ideal for micro-trenching applications where minimal surface disruption is key. The tough HDPE sheath resists impact damage underground, while water-blocking tape and tracer wires support long-term performance and future locating.
Upgrading an existing conduit? Direct install (DI) microduct is built for that. Its smaller profile increases capacity without excavation. The smooth inner wall supports air-blown fiber installation, and moisture barrier tape helps keep water out for reliable moves, adds, or changes later.
Running cable overhead? Aerial-rated microduct includes built-in strength members, either metallic or nonmetallic, to support the load. It’s designed to stand up to UV exposure and changing weather.
Routing fiber indoors? LSZH and riser-rated microduct meet fire safety requirements. These options limit smoke and flame spread, making them suitable for use inside buildings and riser shafts.
Defining the environment first keeps the rest of the design process on track.
With the environment defined, lock in how you plan to install the system.
Microduct products support a range of deployment techniques, including air blowing, cable pulling, and pushing. Their smooth interior and protective design help reduce friction, making them a reliable option for fast, low-impact installation.
Direct buried routes often use micro-trenching to minimize surface disruption. Matching the right cable stiffness to the route helps avoid snags, especially around tight bends or longer runs.
Choosing the right installation method early helps guide later decisions on materials, sizing, and tools.
Now turn to the fiber cable itself, specifically how it will handle the conditions and route layout.
Outdoor exposure requires a jacket that can handle moisture, sunlight, and temperature swings. Polyethylene (PE) performs well in these situations. For indoor spaces, LSZH jackets meet fire and safety standards.
Route layout determines how flexible the cable needs to be. Long, straight runs favor stiffer cables for better blowing distance. Routes with tighter bends call for a more flexible cable that can navigate corners without binding.
The right jacket and flexibility protect the fiber both during install and long after it’s in place.
With cable construction set, you can size the duct to match.
Fiber count and cable outer diameter (OD) drive this decision. For example, a cable with a 3.2–5.8 mm OD typically pairs with an 8 mm inner diameter (ID) duct.
Microduct Selection Guidelines
| Fiber Counts Installed | 1-12F | 24-72C | 96-144C | 216-288C |
| OD of Cable | 1.0-2.0mm | 3.2-5.8mm | 6.8-8.0mm | 8.4-9.2mm |
| Microduct Tube | 3.5mm | 8mm | 10mm | 12mm |
Select the proper size microduct by using the microduct selection guidelines we recommend for Micro-Path™ piping system.
To keep the installation smooth, it is common practice in many piping systems to maintain an OD-to-ID ratio between 0.6 and 0.7. That ratio keeps airflow around the cable while minimizing friction during air-blown installs.
Sizing it right up front gives you longer cable runs and helps protect your fiber over time.
With your design finalized, select the right tools and components to get the job done right.
Blowers, compressors, and lubricants should match your duct size and cable type. Proper air pressure and flow reduce friction and help the cable travel longer distances without damage.
Finish the system with the right accessories. Couplers, branching units, and sealed enclosures keep the network secure and ready for future adds.
Reliable equipment and accessories support a cleaner install and reduce the risk of costly rework.
Once the main design is complete, plan for what’s next.
Multi-way duct bundles make this easy. You can install the fiber you need now and leave open pathways for later. When it’s time to expand, adding new cables doesn’t mean starting over.
In existing routes, Y-connectors and overlay ducts allow you to add fiber without major excavation. Reusing available conduit helps control costs as your network grows.
A little planning here saves a lot of time and money down the road.
From sizing issues to installation delays, small missteps can stall a fiber project. Atkore’s Micro-Path™ microduct piping system is built to help you get it right the first time.
Customizable for your network needs, Micro-Path™ supports a wide range of environments and installation methods:
Learn more about Atkore Micro-Path™ and how it can support your next fiber optic project.