A practical pre-design and RFQ checklist for telecom operators, ISPs, contractors, utilities, and distributors evaluating ADSS, Figure-8, or messenger-supported aerial fiber optic cable.
Published 2026-06-21 · MapleArashi Technical Insights
Aerial cable selection is often reduced to one question: “What is the maximum span?” That question is incomplete. A usable span depends on the cable construction, cable weight, installation sag, installation tension, wind pressure, ice accumulation, temperature range, pole strength, attachment height, route geometry, and the required ground clearance.
The same cable may be suitable for a longer span under light loading and a much shorter span under heavy wind or ice loading. A span value taken from another project, another cable design, or another climate zone must not be treated as a universal guarantee. Final selection should be based on a cable-specific sag-tension calculation or a manufacturer-approved loading table.
Before calculating span and loading, identify which mechanical system will carry the cable. ADSS, Figure-8, and messenger-supported installation are not interchangeable constructions.
ADSS supports its own weight through aramid yarn strength members and contains no metallic messenger. It is commonly selected where electrical isolation, power-line proximity, or elimination of a separate support wire is important.
For additional ADSS design guidance, ADSS fiber optic cable guide and PE sheath versus AT sheath guide explain cable structure, application selection, and electric-field-related jacket requirements.
Figure-8 cable combines the optical cable and a messenger element in one jacket profile. The messenger carries the mechanical load while the optical core remains separated by the web between the two sections.
In a lashed system, a separate messenger wire carries the structural load and the fiber cable is attached to it. This can allow the use of a conventional outdoor cable, but the messenger, lashing wire, hardware, pole loading, and cable weight must be designed as one system.
A reliable quotation or technical proposal requires more than fiber count and cable length. The following parameters should be collected before a cable design is approved.
| Parameter | Required Project Information | Why It Matters |
|---|---|---|
| Maximum and average span | Longest pole-to-pole distance and typical route span | Controls tensile demand and sag |
| Permitted installation sag | Specified percentage or clearance-based sag limit | Lower sag normally increases tension |
| Wind condition | Design wind speed, pressure, exposure category, local code | Adds transverse load to cable and poles |
| Ice condition | Radial ice thickness, density, or local loading class | Adds cable weight and wind area |
| Temperature range | Installation, minimum operating, and maximum operating temperatures | Changes cable length, sag, and tension |
| Ground clearance | Road, railway, river, building, and pedestrian clearance requirements | Determines allowable final sag |
| Pole data | Pole material, class, height, age, loading capacity, and attachment height | Prevents overloading the supporting structure |
| Route geometry | Angles, dead ends, elevation change, crossings, and unequal spans | Changes longitudinal and transverse loads |
| Electrical environment | Voltage level, phase position, cable attachment location, electric-field exposure | Critical for ADSS sheath and hardware selection |
| Fiber requirement | Fiber count, G.652D/G.657 type, tube configuration, future capacity | Defines optical core size and cable weight |
Sag is the vertical distance between the attachment-point level and the lowest point of the cable within a span. Increasing sag generally reduces cable tension, while reducing sag generally increases cable tension. The designer must balance mechanical tension against ground clearance and route constraints.
A specification such as “100 m span” is incomplete unless it also states the loading condition and the assumed installation sag. The final operating sag can differ from the initial installation sag because of temperature change, wind, ice, cable creep, and long-term loading.
Improves clearance but increases cable tension and pole reaction. It may require a stronger cable and stronger support structures.
Reduces tension but consumes vertical clearance and may violate road, railway, river, or utility separation requirements.
Long and short adjacent spans can create unbalanced loads at the pole. Route geometry must be included in the support calculation.
Cable datasheets may use several tensile terms. Their exact definitions and limits must be taken from the cable manufacturer’s design documentation rather than assumed from another supplier’s product.
The controlled tension applied while the cable is being installed and brought to the specified initial sag. Pulling and stringing procedures must remain below the manufacturer’s permitted installation limit.
A manufacturer-defined maximum tension limit for the specified loading case. The meaning, duration, and applicable safety factor should be verified in the product calculation or technical datasheet.
A rated mechanical strength value used as a reference in cable design. RTS is not an instruction to install or operate the cable at that tension. Allowable installation and operating tensions are lower and must be specified separately.
Procurement documents should request the manufacturer’s sag-tension table or calculation report for the proposed cable design, including the assumed wind, ice, temperature, span, sag, and safety factors.
Wind creates a transverse force on the projected cable area. Ice increases cable weight and can also increase the effective diameter exposed to wind. Combined wind-and-ice loading may be more severe than either condition by itself.
Local codes may define loading districts or design combinations. The purchasing team should not substitute a generic “light,” “medium,” or “heavy” label without identifying the standard or numerical assumptions behind that label.
Selecting a mechanically stronger cable does not solve a weak-pole problem. The pole, anchors, guys, crossarms, clamps, dead ends, suspension hardware, splice closures, and cable must be evaluated as one mechanical system.
Clearance must be checked under the governing final-sag condition, not only immediately after installation. Special attention is required at road crossings, railways, rivers, steep terrain, building entrances, and locations with unequal pole elevations.
| Project Condition | Likely Starting Point | Engineering Check |
|---|---|---|
| Power corridor or electrical isolation required | ADSS | Electric field, sheath grade, span, sag, wind and ice |
| Short or medium rural distribution spans | Figure-8 | Messenger type, grounding, clamp compatibility, pole capacity |
| Existing approved messenger available | Lashed outdoor cable | Messenger residual capacity and total added load |
| High wind or ice region | Project-specific design | Combined loading and final-sag clearance |
| Long span or critical crossing | Custom ADSS or engineered support system | Manufacturer calculation and structural review |
| Metallic messenger prohibited | ADSS or dielectric Figure-8 | All-dielectric construction and hardware confirmation |
For a product-level comparison, see ADSS vs Figure-8 Self-Supporting Aerial Cable .
Sending only “24-core aerial cable, 100 km” is not enough for a technically responsible quotation. Include the following information:
MapleArashi can review these project inputs and recommend a suitable cable structure, but final structural approval remains the responsibility of the project engineer, utility, or authority governing the route.
Send us your span, wind, ice, temperature, pole, clearance, electrical-environment, fiber-count, and route information. We will review the project inputs and recommend an appropriate ADSS, Figure-8, or messenger-supported cable structure.
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