Aerial Work

# What Strand and Lash Installation Really Means

TLDR

Strand and lash means placing a tensioned steel **messenger strand** first, then binding fiber to it with **lashing wire**. Sag, hardware and **pole loading** decide whether it survives.

Last updated October 20, 202613 min read

Strand and lash is a two pass aerial method. A galvanized steel messenger strand is pulled span to span, dead ended, and tensioned to a sag target. A lashing machine then rides that strand and wraps lashing wire around the strand and the cable together, binding the fiber to the strand along the full span.

## What does strand and lash actually mean?

The phrase names the two passes. The first pass places the messenger strand, a stranded galvanized steel wire rope that is dead ended at terminal poles, supported at intermediate poles, and pulled to a specified sag. The second pass places the cable and lashes it to that strand with a spinning lasher that wraps lashing wire in a continuous helix.

The fiber cable itself carries almost no mechanical load in this design. It hangs on the strand. That is why the strand class, the hardware at each pole, and the sag setting matter more to long term reliability than the cable specification does.

The alternative is self supporting cable, where the tension member is built into the cable. That removes a pass but pushes load into a larger diameter cable and into every pole. Strand and lash keeps the load in a component sized for it, and lets an owner add cables to the same strand later.

## Why the messenger strand does all the work

Strand is specified by rated breaking strength class, commonly written as 6M, 10M or 16M, meaning thousands of pounds of rated strength. The class is chosen from span length, expected load, and the number of cables the owner plans to lash to it over the life of the plant. Undersizing the strand to save material cost is the single most expensive shortcut on an aerial build, because correcting it later means restringing the entire run.

At each pole the strand lands on hardware that transfers its load into the pole: a bolt and washer set, a suspension or clevis, and at dead end locations a strand clamp or automatic dead end. Guying handles the unbalanced pull at corners, at ends of runs, and anywhere the direction of tension changes. A dead end without a matching down guy or sidewalk guy pulls the pole out of plumb, and the run slowly loses the clearance it was engineered to hold.

Bonding is part of the same system. Strand is bonded so induced and fault current has a defined path, which makes bond wires at the pole and ground rod inspection items rather than optional trim.

## How is sag and tension set in the field?

Sag is the vertical drop of the strand at midspan relative to the attachment points. It is not a number a crew guesses. Sag is read off a sag chart or table built for the strand class, the design span, and the temperature at the time of stringing, because steel lengthens as it warms and shortens as it cools.

Pull the strand too tight and you buy two problems: excess load on poles and guys during a wind event, and a run that has no reserve when temperatures drop and the strand contracts. Pull it too loose and midspan clearance disappears, which matters most over roadways, driveways and parking areas where a low span becomes a vehicle strike waiting to happen.

Field verification is straightforward. A dynamometer confirms tension during pulling, and a sag measurement at midspan confirms the result against the chart. Photographing the dynamometer reading and the measured midspan clearance at representative spans creates the record that answers a clearance question months later without a second field visit.

- Sag is temperature dependent: the same tension produces different sag on a cool morning than on a hot afternoon.
- Clearance requirements are highest over roadways and lowest over areas that only see pedestrians.
- Every added lashed cable increases load, so the original sag design should anticipate future attachments.
- Corners, dead ends and long spans are the locations where guying and anchor capacity get verified, not assumed.

## What happens during the lashing pass?

The cable is paid off the reel and placed alongside the strand, either pulled through blocks hung on the strand or figure eighted on the ground at a mid point and back pulled. Both methods exist to position the cable without exceeding its rated pulling tension or minimum bend radius.

The lasher is then loaded with a spool of lashing wire, clamped over the strand and cable, and pulled along the span. It rotates as it travels, wrapping the lashing wire in a helix that binds the cable to the strand. Lash wire terminates at each pole in a lashing wire clamp, so a failure in one span cannot unwind the next.

Stainless lashing wire is the sensible default in coastal Florida. Salt air will attack galvanized wire faster near the shoreline, and a corroded lash line unravels slowly and quietly until a span sags out of clearance. Cable spacers, or lashing wire spacers, are added where the cable needs to stay separated from the strand at obstructions.

- Set reel brakes and a swivel where required so the cable is never allowed to twist during placement.
- Respect the cable minimum bend radius at every block, roller, corner pole and riser.
- Terminate lash wire with clamps at each pole so damage stays contained to one span.
- Inspect the jacket after placement, because a lasher run over a nicked jacket is the cheapest defect to find and the most expensive to ignore.

## Where does slack go, and why does it matter?

Slack is stored cable held on the pole line for future use. It is what allows a splice to be redone, a damaged section to be cut out, or an enclosure to be lowered to a bucket for work without cutting into live spans. A build with no stored slack turns a routine repair into a re splice of an entire section.

Slack is stored in loops on snowshoes, which are frames lashed to the strand that hold the loop at a controlled bend radius, or coiled at the pole in a storage bracket. The controlling rule is bend radius: fiber coiled tighter than its rated radius shows up as macrobend loss on an OTDR trace, usually worse at 1550 nm than at 1310 nm.

Slack placement should be planned, not improvised. Storage near splice locations, at road crossings, and at transitions to underground gives future crews something to work with. Slack quantities and locations belong in the as built so the next technician does not have to search a pole line for it.

## When is overlashing an option instead of new strand?

Overlashing places a new cable on an existing strand, lashing it to the strand and the existing cable in one pass. It is faster, it avoids new pole hardware in many cases, and it can avoid a new attachment application where the pole owner treats an overlash as a modification of an existing attachment.

Overlashing is not free of engineering. The added cable increases wind area and weight on a strand and a pole line that were designed for the original load, so the pole owner will normally require a loading review before approving it. Someone also has to look hard at the strand already up there: corrosion, broken outer wires, previous damage, or a strand that is already sagging out of clearance disqualifies the span until it is corrected.

The decision comes down to condition and headroom. If the strand is sound, the pole line has capacity, and clearances hold with the added load, overlash is the better path. If any of those fail, new strand is the honest answer.

## Common strand and lash defects and what causes them

Most aerial rework traces back to a few repeatable causes. Catching them during construction is far cheaper than finding them in a post construction audit by the pole owner.

| Defect found | Usual cause | Correction |
| --- | --- | --- |
| Low midspan clearance | Sag beyond the design target, or cable added without a loading review | Retension to the sag chart value, or shorten the span |
| Pole leaning at a dead end | Missing or undersized guy and anchor for the unbalanced pull | Install or upsize the guy and anchor, then re plumb and retension |
| Lash wire unwinding | Corroded lashing wire or a missing lash clamp at the pole | Relash the span with stainless wire and terminate at each pole |
| High loss at a splice point | Slack coiled inside the fiber minimum bend radius | Rework the loop on a properly sized snowshoe and retest |
| Jacket damage on a new run | Cable dragged over pavement or hardware during placement | Cut out and splice the damaged section, or replace the span |
| Attachment flagged by the pole owner | Attached outside the communications space or without a permit | Correct the height and close out the permit record |

## How should an owner inspect a finished strand and lash span?

Walk the route from the ground first, then check a sample of poles from a bucket. Most strand and lash defects can be seen by a trained eye on foot. A structured walk-down right after the lashing pass catches them while the crew and equipment are still on the job, which is when a fix costs the least.

From the ground, sight along each span and compare it with its neighbors: a span that hangs clearly lower deserves a measurement, not a guess. From the bucket, check that hardware is seated and tight, that the jacket is undamaged where it passes through clamps, and that enclosures have drip loops. Photos from the walk-down go into the closeout record and give the pole owner's post construction inspector a dated reference.

- A continuous lash helix with no open wraps, ending in a clamp at each pole.
- Sag that matches adjacent spans, with measured clearance over roads and driveways.
- Guys and anchors at every corner and dead end, with guards where pedestrians pass.
- Bond connections made up and secured, not left hanging on the pole.
- Slack loops on snowshoes at the planned locations, with no tight coils.
- Cable tags or markers wherever the owner's standard calls for them.

## How Florida conditions change strand and lash work

Wind loading dominates. Florida sits in an extreme wind environment, and pole line design accounts for that with pole class, guying and strand selection. A run that would be routine elsewhere may require a stronger strand class or additional guying here, and that is an engineering input, not a field decision.

Corrosion is the second factor. Near the coast, hardware, lashing wire and bond connections see salt laden air continuously. Material selection at the front end, particularly stainless lashing wire and appropriate hardware finishes, is what keeps a ten year old run from needing a full hardware replacement.

Vegetation is the third. Growth runs year round here, so a span placed just clear of a canopy in winter can be inside it by summer. Trim needs are identified during survey and coordinated before the lashing pass.

Strilla Communications Company runs strand and lash work with owned equipment and crews across Volusia County and Central Florida, coordinated through a single point of contact, with photo documentation and as built records delivered as part of closeout.

## Key takeaways

- In a strand and lash build, the strand class and the pole hardware decide long term reliability more than the fiber cable does.
- Sag is set from a chart for the strand class, span length and air temperature at the time of stringing, never by eye.
- Slack coiled tighter than the fiber's minimum bend radius shows up as added loss on an OTDR trace, usually more at 1550 nm than at 1310 nm.
- A walk-down after the lashing pass is the cheapest point to catch open lash wraps, missing guys and low spans.

## Key terms

**Messenger strand**: A stranded galvanized steel wire rope tensioned between poles to carry the weight of aerial cable. It is specified by rated breaking strength class, dead ended at terminal poles, supported at intermediate poles and bonded so that fault current has a defined path to ground.

**Snowshoe**: A frame lashed to the messenger strand that holds a loop of stored fiber slack at a controlled bend radius. Snowshoes are usually installed in pairs near splice points and transitions, so a future crew has spare cable to work with during a repair.

**Sag chart**: A table or curve that gives the correct midspan sag or tension for a strand class, span length and temperature. Crews read the target from the chart when stringing, because steel strand lengthens as it warms and shortens as it cools.

**Down guy**: A strand anchored in the ground that holds a pole against an unbalanced pull, such as at a corner or the end of a run. Without one, the tension in the messenger strand slowly pulls the pole out of plumb and reduces midspan clearance.

*Strand and lash components and what each one does*

| Component | Job in the system | What happens when it is missing or wrong |
| --- | --- | --- |
| Messenger strand | Carries the weight and wind load of every lashed cable | An undersized strand forces a restring when cables are added |
| Suspension clamp and bolt | Transfers strand load into tangent poles | Loose hardware lets the strand slip and shifts sag between spans |
| Dead end | Terminates strand tension at run ends and sharp corners | A poorly seated dead end can slip under storm load |
| Down guy and anchor | Balances the pull at corners and dead ends | Poles lean and midspan clearance drops over time |
| Lashing wire and clamps | Binds the cable to the strand, span by span | Corroded wire unwinds and the cable sags away from the strand |
| Snowshoe | Stores slack at a safe bend radius | Tight coils add optical loss and leave nothing for repairs |

*Aerial strand and lashed fiber*

## What this means for your project

Strand and lash risk is concentrated in a few decisions made before the crew mobilizes: strand class, the slack plan, and guying at corners and dead ends. Each costs little to get right at design time. Getting one wrong shows up later as a restring, a violation notice from the pole owner, or a repair that needs new splices because no slack was stored nearby. Write those items into the scope with the same care as the unit prices.

Schedule risk usually sits outside the lashing itself. Make-ready, tree trimming and traffic control permits decide when a crew can work a segment, so tie mobilization to segments where all three are cleared. For the record, ask for sag readings at representative spans, photos of hardware and guying, slack locations and quantities, and attachment heights listed by pole tag. Those records answer pole owner audits and speed storm repairs without a return trip to the field.

## Related reading

- [Strand and lash construction servicesScope, process and specifications for new strand and lash builds.](https://strillacommunications.com/services/aerial-cable-construction/strand-and-lash)
- [Messenger strand installationHow strand is framed, tensioned, guyed and bonded before any cable is lashed.](https://strillacommunications.com/services/aerial-cable-construction/messenger-strand-installation)
- [Overlashing an existing strandWhen adding a cable to strand already in place is the better path.](https://strillacommunications.com/services/aerial-cable-construction/overlash)
- [Why make-ready sets the aerial scheduleThe pole owner process that has to clear before strand goes up.](https://strillacommunications.com/blog/how-make-ready-work-supports-aerial-fiber-builds)
- [How aerial cable construction worksA start to finish guide to aerial builds, from pole survey to closeout.](https://strillacommunications.com/resources/guides/how-aerial-cable-construction-works)
- [Aerial construction project typesThe kinds of aerial work Strilla takes on across Central Florida.](https://strillacommunications.com/projects/aerial-construction-projects)

## Frequently Asked Questions

**Is strand and lash better than self supporting aerial cable?**: It depends on the run. Self supporting cable places the tension member inside the cable, saving a pass but adding wind load at every pole and locking the pole line into one cable. Strand and lash separates the load path from the cable, generally handles longer spans and heavier loading better, and lets an owner overlash additional cables later without restringing.

**How much slack should be stored on an aerial run?**: Enough to lower an enclosure to working height and to allow at least one future repair without cutting into adjacent spans. Storage is typically placed at splice locations, at major crossings, and at underground transitions. The controlling constraint is bend radius: slack has to sit on a snowshoe or bracket that holds the fiber above its rated minimum radius, or it shows up as loss on an OTDR trace.

**Does overlashing require permission from the pole owner?**: Almost always. Even where an overlash is treated as a modification of an existing attachment rather than a new one, pole owners generally require notification and a loading review, because the added cable increases weight and wind area on hardware designed for the original load. Building an overlash without that approval risks removal orders and back charges.

**What documentation should a strand and lash job produce?**: A closeout package should include the as built route with pole identifiers, strand class and hardware used, sag or tension verification at representative spans, slack storage locations and quantities, splice locations, OTDR results after splicing, photo documentation of attachments and guying, and the permit or attachment approvals that authorized the work.

**Who owns the messenger strand after it is installed?**: Usually the company that holds the attachment permit for it. The strand, its hardware and the cables lashed to it belong to that attacher, not to the pole owner. Ownership matters later. Anyone who wants to add a cable to that strand needs the strand owner's agreement on top of the pole owner's process, and the strand owner is the party responsible for moving it when a pole is replaced.

**What happens to a strand and lash run when a pole is replaced?**: The attacher that owns the strand and cable transfers them to the new pole after the pole owner sets it and sends notice. The run is moved to the correct height on the new pole, the hardware is reinstalled, and guying is checked, because the new pole may stand in a slightly different spot. The old pole stays up until every attacher has transferred, which is why transfers so often cause delay.

## Related services

- [Strand and LashStrand and lash aerial cable construction in Central Florida: messenger strand framing, tensioning to sag, machine lashing, and clearance checks.](https://strillacommunications.com/services/aerial-cable-construction/strand-and-lash)
- [Aerial Cable ConstructionPole line construction, strand placement, lashing, and aerial fiber installation with make-ready coordination and NESC clearance verification.](https://strillacommunications.com/services/aerial-cable-construction)
- [Messenger Strand InstallationMessenger strand installation in Central Florida: pole framing, guying and anchoring, tensioning to sag charts, and strand bonding with verified continuity.](https://strillacommunications.com/services/aerial-cable-construction/messenger-strand-installation)
- [OverlashOverlash new fiber onto existing messenger strand in Central Florida. Strand condition inspection, loading review, and clearance verification.](https://strillacommunications.com/services/aerial-cable-construction/overlash)
- [Aerial Fiber PlacementAerial fiber placement in Central Florida: lashed loose tube, figure-8, and ADSS cable placed with tension control and planned slack storage.](https://strillacommunications.com/services/aerial-cable-construction/aerial-fiber-placement)

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Source: https://strillacommunications.com/blog/what-strand-and-lash-installation-really-means