Cable Placement Underground

Purpose

Place fiber cable in the duct without exceeding its tension rating or its minimum bend radius, and leave the slack the splicers need where they need it. Fiber damaged during the pull may test fine today and fail later. Missing slack at a splice point can mean a new cable.

When to Do It

• Trigger: every duct on the route is proven and has pull tape where specified (UG-10).
• Prerequisites: a pull plan, cable on site with its manufacturer data sheet (pull rating and bend radius), traffic control at enclosures.
• Previous step: UG-10 Duct Proving and Pull Tape.
• Next step: UG-12 Restoration and Cleanup.

Roles

• Foreman: owns the pull plan and stops the pull on any tension or jacket problem.
• Winch operator: sets the tension limit and logs tension during the pull.
• Feed-end crew: pays the cable off the reel, lubricates it and watches for jacket damage.
• Intermediate enclosure crew: keeps the cable on rollers and quadrant blocks, and figure-8s it where planned.
• Air-blowing technician: sets up and runs the blowing machine per the manufacturer.

Equipment and Materials

• Tension-limited winch, or a dynamometer, set below the cable’s rating.
• Breakaway swivel rated at or below the cable’s maximum pulling tension, between the pulling rope and the cable grip.
• Cable rollers and quadrant blocks for every enclosure.
• Cable reel trailer or reel stands.
• Cable pulling lubricant approved by the cable manufacturer.
• Cable air-blowing machine and compressor for microduct.
• Radios at both ends and at every intermediate enclosure.
• Cable tags per owner spec.

Safety

Procedure

Hold Points

Records to Keep

• Tension log for each pull.
• Cable footage marks at each enclosure.
• Slack stored at each enclosure and splice point.
• Cable reel ids and lengths.
• Photos of slack coils and tags.

Common Mistakes

• Pulling from the wrong end. Tension multiplies through bends; plan the direction.
• No tension monitoring. You cannot prove the cable was not overstressed.
• Tight slack coils. A coil tighter than the at-rest bend radius adds loss or breaks fibers.
• Missing slack at splice points. The splicer cannot reach the vehicle, and the cable may have to be replaced.
• Rough enclosure edges. Unprotected duct ends and lids cut the jacket; use quadrant blocks.

Standards and References

• ANSI/TIA-568.3: OSP cable pull strength and bend radius.
• Cable, lubricant and air-blowing equipment manufacturer instructions.
• 29 CFR 1926 Subpart AA: confined spaces in construction (1926.1201 to 1926.1213), the rule for construction work.
• 29 CFR 1910.268: telecommunications, including guarding manhole and vault openings and testing the air in manholes and unvented vaults in paragraph (o). Paragraph (a) excludes construction work.
• 29 CFR 1910.146: permit-required confined spaces in general industry, which covers telecom maintenance and service work. Paragraph (a) excludes construction.
• 29 CFR 1926 Subpart M: fall protection in construction, including covers and guardrails at holes such as open enclosures (1926.501(b)(4)).
• MUTCD Part 6: temporary traffic control at enclosures.
• Owner construction standards for slack and tagging.

On the Map

• Handhole Slack Coil: stored cable coiled within bend radius.
• Underground Splice Closure: closure in a handhole or vault, fed by the slack you store.
• Buried Drop: drop cable or duct from a pedestal or handhole to the building.
• Handhole: where rollers, quadrant blocks and slack coils go.
• Innerduct and Microduct: the smaller ducts the cable is pulled or blown into.

Related Tools

• Pull Planner: plan pull direction and assist points, and estimate tension through bends.
• Duct Fill: check that the cable fits the duct before you pull.
• Cable Footage and Slack Estimator: add up the cable the pull needs, including slack coils, and compare it with the reel.