AE Aerial AE-08 Step 8 of 12
Strand Placement and Tensioning
Pull strand, dead-end one terminal, tension from the far end to the owner's sag chart, dead-end it, then bond and check clearances.
Crew
- Foreman
- Lineworker
- Reel Operator
- Ground Worker
Hazards
- Electrical Contact
- Stored Energy in Tensioned Strand
- Strand Whip or Reel Runaway
- Struck by Vehicles
Purpose
Put up messenger strand at the right sag and tension, terminated and bonded per the design. The strand carries the cable for its whole life. Too tight and it overloads poles and guys under ice and wind. Too loose and the cable sags below its midspan clearance.
When to Do It
- After framing (AE-05), anchors (AE-06) and guys (AE-07 Down Guys and Guy Guards) are in place and verified.
- With traffic control set for every road the strand crosses (AE-04).
- Next step: AE-09 Cable Placement and Lashing.
Roles
- Foreman: has the owner’s sag and tension chart on site and checks tension, dead-ends and bonds.
- Lineworker: places strand in the clamps, makes up the dead-ends, tensions the strand with the puller and installs bonds.
- Reel operator: controls the reel brake so the strand pays out smoothly.
- Ground worker: watches the strand across roads and driveways and keeps the public clear.
Equipment and Materials
- Strand reel trailer or reel stand with a brake.
- Stringing blocks where the strand is pulled through rather than placed directly in clamps.
- Dynamometer, or tools to measure sag.
- Strand puller or come-along.
- Preformed strand dead-ends matched to the strand size.
- Approved strand splices only.
- Bonding clamps and ground wire.
- Rubber insulating gloves rated for the voltage on the poles, inspected before each use.
- Temporary bonds and roller (running) bonds of at least No. 6 AWG copper. A roller bond rides on the strand as it moves, so the strand stays grounded while it is pulled.
- Voltage detector rated for the work.
Safety
Procedure
- Test for voltage before anyone touches pole metal.
- Test vertical power ground wires, metal power conduit and streetlight fixtures in or near the communications space, unless they are visibly bonded to the strand.
- Test existing strand and hardware.
- If anything tests energized, stop, keep everyone clear and call the power owner.
- Set temporary bonds before you pull, so the new strand is grounded from the start.
- On joint-use poles, bond the new strand to an existing tested protective ground, such as a vertical ground wire tied to the power neutral.
- On lines with no power on the poles, bond the strand as close as possible to each power crossing.
- When thunderstorms are possible, also ground strand on lines with no power to an existing ground listed in 29 CFR 1910.268(m)(4) as you place it (29 CFR 1910.268(m)(6)(i)), so it is already grounded if a storm moves in.
- Put on insulating gloves. Attach the ground end first, then the strand end.
- Use roller bonds where the strand moves through the bond, and restrain them.
- Set up the strand reel and pull strand through the clamps or blocks.
- Use the stationary-reel or moving-reel method, as the site allows.
- Keep tension on the reel brake so the strand does not backlash or drop into the road.
- Restrain the strand against upward movement where the grade rises at a pole and where it crosses under power.
- Wear insulating gloves and keep your body off the strand where the poles carry exposed energized power.
- Join reel lengths only with approved strand splices, only where the owner’s standard allows, before the section is tensioned.
- Set the strand in the corner hardware or corner blocks per the design, with the corner guys in place (AE-07).
- Where the design dead-ends a corner both ways, treat each side as the terminal of its own section.
- Dead-end the strand at the first terminal pole with a preformed dead-end, or the dead-end the owner’s standard specifies, guyed against the pull.
- Make it up fully before anyone tensions. All the tension you put in next pulls against this dead-end.
- Place the strand in the intermediate strand clamps hand-tight, so it can still slide while you tension the section.
- Tension the strand from the far terminal pole to the owner’s sag and tension chart with a strand puller.
- Read the chart for the span length and the current temperature (per owner sag and tension chart).
- Measure with a dynamometer or by sag measurement.
- Stay out of the line of pull while the strand is under tension.
- Make up the second dead-end at the far terminal pole while the puller holds tension. This dead-end is guyed against the pull too.
- Release the puller under control only after the dead-end is fully made up.
- Then tighten the intermediate clamps and finish the corner hardware per the design.
- Recheck the sag against the chart.
- Bond the strand permanently per the design, at the poles and intervals the owner specifies (per owner spec).
- Remove the temporary bonds only after the strand is tensioned, dead-ended and permanently grounded.
- Put on insulating gloves. Remove the strand (line) end first, then the ground end.
- Check clearances at worst-case sag over roads, driveways and walks (per National Electrical Safety Code (NESC) Table 232-1).
Hold Points
Records to Keep
- Sag or tension readings for each section, with span length and temperature.
- Strand footage by section.
- Locations of dead-ends, splices and permanent bonds, including any guy-to-strand bonds per AE-07.
- Temporary bond locations, and confirmation that each was removed after permanent bonding.
- Voltage test results, and any energized metal reported to the power owner.
- Photos of dead-ends, corners and bonds.
Common Mistakes
- Tensioning without the chart. Tension by feel is either too tight or too loose.
- Loose clamps left hand-tight after tensioning, so the strand creeps and the sag changes.
- Unguyed dead-ends. The pole leans as soon as the strand is tensioned.
- Tensioning before the first dead-end is made up, or releasing the puller before the second one is. The strand has nothing to hold it and runs back or whips.
- Splices in the wrong place, such as mid-span where the owner does not allow them.
- Forgetting the bond after tensioning.
- Bare hands on new strand under energized power. The strand is not grounded until someone grounds it.
- Pulling temporary bonds early, or removing the ground end first, which leaves the strand ungrounded with a hand on the bond.
- No restraint at an upward grade change. The strand lifts toward power the moment it takes tension.
Standards and References
NESC (IEEE C2)for clearances, loading and bonding.- Owner construction standards for sag and tension charts, dead-ends, splices and bonding.
- Strand hardware manufacturer instructions.
29 CFR 1910.268 § (m)(3), (m)(5), (m)(6), (n)(1)for voltage testing, temporary bonds and handling strand near power.- OSHA 29 CFR Part 1926 for construction work, which 29 CFR 1910.268 excludes (1910.268(a)(2)(i)). Your employer’s safety program says how to comply.
MUTCD Part 6for traffic control at road crossings.
On the Map
- Messenger Strand: galvanized steel strand tensioned between poles to carry lashed cable.
- Strand Dead-End: the termination at a terminal pole, guyed against the pull.
- Strand Clamp: holds the strand to the pole hardware once tensioned.
- Vertical Ground and Bonding: where the strand is bonded to the pole ground.
- Corner Pole and Bisect Guy: how the strand turns a corner.
- Midspan Clearance: the clearance checked at worst-case sag.
Related Tools
Not applicable: no FAHMY tool covers sag and tension. Use the owner’s sag and tension chart.
AE-08 · Field Checklist
Checklist
0/15items ticked
Tick each procedure step and hold point as the crew completes it. Ticks stay on this device only. They are a personal aid, not a hold-point release or a project record; follow the owner’s sign-off process.
OSP Map · Pole Detail
On the Map
- Messenger StrandGalvanized steel strand tensioned pole to pole that carries the lashed fiber cable.
- Strand Dead-EndTermination of the strand at a terminal pole, guyed against the pull.
- Strand ClampSuspension clamp on the through-bolt that holds the messenger strand to the pole.
- Vertical Ground and BondingThe pole’s vertical ground wire; the strand is bonded to it per NESC and owner spec.
- Corner Pole and Bisect GuyAngle pole guyed on the bisector of the line angle.Drawn in the plan view
- Midspan ClearanceHeight of the cable’s lowest point over roads, drives and walks (NESC Table 232-1, owner spec).Drawn in the route profile