For outdoor fiber jumpers, choose TPU when the cable lives exposed (tower runs, repeated flexing, abrasion, oil, and UV), and choose LSZH when the cable enters occupied or enclosed space, where fire behavior (low smoke, no halogen) matters more than mechanical toughness. TPU (thermoplastic polyurethane) is the mechanical specialist; LSZH (low smoke zero halogen) is the fire-safety specialist. They solve different problems, which is why most outdoor assembly lines offer both.
This page is the decision guide for one pairing. For the full jacket chemistry landscape (OFNP/OFNR ratings, PVC, PE, and material-by-material grades), see our fiber optic cable jacket guide. For how the jacket fits into the complete cable build, see the ODC construction and options guide.
What each material actually is
TPU (thermoplastic polyurethane). A flexible, rubber-like polymer jacket known for outstanding abrasion resistance, tear strength, and repeated-flex endurance. It tolerates oils, fuels, and many chemicals, stays flexible at low temperature (TPU formulations serve well below freezing), and handles UV exposure well in outdoor-grade formulations. It is the default jacket for tower jumpers, tactical/deployable cable, and drag-and-retrieve applications. Wet or humid routes call for polyether-based TPU (hydrolysis resistance); oil-heavy sites call for polyester-based TPU. Datasheets may label the same jacket family PUR; see the FAQ.
LSZH (low smoke zero halogen). A flame-retardant polyolefin-class compound engineered for fire behavior: it self-extinguishes, emits little smoke, and releases no halogenated (corrosive, toxic) gases when burned. Building, transit, and data-center specifications require it, or an equivalent fire rating, where cables run through occupied space, risers, tunnels, and enclosures near people or electronics. Mechanically it is stiffer and less abrasion-tolerant than TPU, and standard grades stiffen noticeably in deep cold.
TPU vs LSZH: property-by-property
| Property | TPU | LSZH |
|---|---|---|
| Abrasion / cut-through resistance | Excellent | Moderate |
| Repeated flexing / bend fatigue | Excellent (deployable-cable class) | Limited (fixed-installation class) |
| Low-temperature flexibility | Excellent; TPU formulations stay flexible well below freezing | Moderate; stiffens in deep cold |
| UV / weather endurance (outdoor grade) | Excellent | Good, formulation-dependent |
| Oil / fuel / chemical exposure | Excellent | Poor to moderate |
| Flame behavior | Burns; standard TPU is not a fire-rated jacket | Self-extinguishing, flame-retardant |
| Smoke / toxicity in fire | Dense smoke; halogen content varies by formulation | Low smoke, zero halogen (its core purpose) |
| How the claim is proven | Mechanical datasheet values (IEC 60794-series cable tests) | IEC 60754 / 61034 / 60332 test reports |
| Typical cost position | Higher material cost | Lower material cost |
| Where it belongs | Exposed outdoor runs: tower, mast, ground, reel | Occupied/enclosed space: risers, equipment rooms, tunnels, cabinets indoors |
One nuance worth knowing: flame-retardant, halogen-free TPU compounds exist and are used in tactical and specialty industrial cable. They narrow the gap without closing it: availability is limited, cost runs higher, and the fire performance still needs the same IEC test evidence as any LSZH claim. Treat FR-TPU as a specialty option, not a default.
Choose TPU when
- The cable is exposed on a tower, mast, or rooftop: UV, wind-driven rain, temperature swing, and constant micro-movement against structure
- The route includes drag, retrieval, or repeated handling: deployable links, reels, temporary installations, broadcast
- Abrasion or crush contact is expected: ladder rungs, cable trays shared with other utilities, ground-level exposure
- The environment includes oil, fuel, or industrial chemicals: energy sites, workshops, transport hubs
Choose LSZH when
- The outdoor run terminates inside an occupied building: the jumper enters an equipment room, shelter, or cabinet in public or staffed space, and fire code applies
- The route passes through enclosed or poorly ventilated space: tunnels, risers, ceiling voids, transit infrastructure
- The project specification calls for halogen-free construction, common in transit, utility, data-center, and European project specs
- The cable is fixed-installed and protected, ducted or tray-routed, where TPU’s mechanical premium buys nothing
Match the jacket to the route segment
The TPU vs LSZH outdoor fiber cable decision gets easier once you stop treating a link as one environment; most routes cross several. Decide per segment, and let the most demanding segment rule the whole run:
| Route segment | Dominant threat | Jacket that owns it |
|---|---|---|
| Tower / mast / rooftop, exposed | UV, abrasion, flex, weather | TPU |
| Ground-level or frequently handled runs | Abrasion, crush, repeated handling | TPU |
| Duct or direct burial feeder | Moisture, soil, long static runs | PE (over armor where needed) |
| Building entry into occupied space | Fire code, smoke, toxicity | LSZH |
| Riser / tunnel / ceiling void | Fire spread and smoke in enclosed space | LSZH |
| Equipment room / indoor cabinet | Fire behavior near people and electronics | LSZH (or the project’s fire rating) |
The hybrid reality: most tower links want both
A typical FTTA jumper runs from the BBU/DU shelter up the monopole to the RRU/RRH, and it lives in both worlds: exposed on the tower, code-governed once it enters the shelter or equipment room. Applied here, the most-demanding-segment rule has a sharp edge. The moment any part of the run crosses occupied space, the fire requirement travels the whole length. And a run that never leaves the tower should not pay for a fire rating it never needs. On real sites the argument rarely sits on the tower; it sits at the building entry, where the shelter fire spec and the tower’s exposure spec meet.
Where the link is long or the environments differ sharply, a hybrid build is often the cleaner answer: TPU on the exposed outdoor section, LSZH from the building entry inward, transitioned at a closure or entry cabinet. Many projects instead standardize on one jacket per link type and state it in the BOM; what matters is that the choice is deliberate. For the full tower-routing picture, see our FTTA fiber cable guide.
What the fire standards actually say
“LSZH” is a material claim, and it is provable. When a project requires it, the datasheet should trace to three IEC test families:
- IEC 60754-1/-2: the “zero halogen” claim. Halogen acid gas evolved on combustion (the halogen-free criterion is typically under 0.5 %), plus acidity limits (pH and conductivity) on the evolved gases.
- IEC 61034: the “low smoke” claim. Smoke density measured as light transmittance in a smoke chamber, with 60 % or better transmittance the commonly cited low-smoke threshold.
- IEC 60332-1 and IEC 60332-3: flame retardance. Vertical flame tests on a single cable and on bunched cables.
Two cautions for international projects. In North America, the NEC framework lists cables as OFNP/OFNR (plenum/riser), backed by the UL 910 and UL 1666 fire test methods; LSZH is not a one-to-one substitute for those listings, so check which framework the project specifies. In Europe, CPR (EN 50575) assigns Euroclasses (Eca up to B2ca, with s/d/a suffixes for smoke, droplets, and acidity) to cables in permanent building works. The outdoor-only segment usually sits outside CPR scope, but the segment entering the building does not, so confirm the required class against the project specification. Outside those frameworks, Gulf and Southeast Asian telecom projects commonly follow IEC fire-test practice with halogen-free requirements, while Latin American and African specs vary by project owner. State the applicable framework in the RFQ rather than assuming one.
Mechanical and environmental claims (flex, abrasion, temperature cycling) trace to the IEC 60794 cable test family, the companion standard set to the fire tests above.
Ask for test reports on the jacket compound, not just the cable model: a jacket can only be called LSZH when the compound itself passes.
Common jacket-selection mistakes
Most outdoor jacket failures trace back to a mismatched material choice, not a bad cable. Five mistakes cause most of them:
- Assuming TPU means halogen-free. It does not. Polyurethane jackets are not automatically halogen-free; if the spec requires halogen-free, state it explicitly.
- Specifying LSZH for a fully exposed tower run. You pay for fire behavior the route never uses and give up abrasion life the route needs every day.
- Treating LSZH as a universal outdoor upgrade. LSZH is a fire specification, not a weather specification; outdoor-grade weathering is a separate formulation property.
- Burying a TPU jumper. TPU is for exposed and handled runs; burial wants a PE feeder, usually armored.
- Copying the jacket from a previous BOM. Routes change; the jacket decision belongs to the current route, not to the reorder.
And when neither is right
- PE (polyethylene): the economical outdoor workhorse for duct and direct-burial feeders. Excellent moisture and UV endurance, stiff handling, and flammability in standard grades that excludes it from occupied-space codes. Not a jumper material; a feeder material.
- Armored variants: corrugated steel tape or steel-wire armor under the outer jacket for rodent and crush exposure. Armor adds protection, weight, and bend radius; the outer jacket choice (TPU/LSZH/PE) still applies over it. Ingress itself is the connector’s job (IP67/IP68 ratings); the jacket handles exposure. For the full threat picture (rodents, water, crush, and the constructions against each), see the harsh environment cable guide and our armored outdoor patch cord guide.
- Fire-rated indoor jackets (OFNP/OFNR): a different framework (NEC) from the LSZH concept. If the run enters a North American plenum or riser space, the rating discussion changes. The jacket guide maps that landscape.
How to spec the jacket in your RFQ
Jacket choice becomes real in the BOM line. A complete assembly line reads like this:
ODC-2 to duplex LC, OS2 ITU-T G.657.A2, TPU jacket, UV-stabilized outdoor grade, 5.0 mm OD, 40 m, per-unit IL/RL test report.
Bend-insensitive G.657.A fiber is the jumper default; G.652.D belongs to the backbone the jumper patches.
Six things to confirm with any supplier before ordering:
- Jacket material and mechanical ratings on the datasheet: TPU / LSZH / PE stated by name, not implied by “outdoor”, with tensile, crush, and bend radius values stated
- Outdoor-grade formulation: UV stabilization and the temperature rating stated (BWNFiber’s ODC jumper datasheets rate working and storage at −20 °C to +70 °C; confirm the range matches your site)
- Fire test evidence behind LSZH claims: IEC 60754 / 61034 / 60332 reports for the compound
- Per-segment jackets in the BOM: on a hybrid link, both jackets named with the transition point
- Sample or first-article confirmation: for project volumes, approve the jacket on a sample assembly before the bulk run
- MOQ per jacket: TPU and LSZH runs can carry different production minimums; confirm both before splitting one project across two jackets
Three route profiles, three BOM lines:
| Route profile | Jacket call | What the BOM line says |
|---|---|---|
| Tower run that never enters a building | TPU throughout, no fire rating needed | ODC-2 to duplex LC, G.657.A2, TPU jacket, 40 m |
| Tower run entering an occupied shelter | TPU to the entry cabinet, LSZH inward | both jackets named, transition point stated |
| Duct or direct-burial feeder segment | PE over armor, jumper territory ends | feeder-class armored cable, PE jacket |
The same six checks apply to every row; the profile only decides which jacket carries the route.
Send your supplier the route description per segment (exposed / ducted / occupied), the handling profile (fixed, reeled, dragged), any chemical exposure, and the applicable fire specification. Photos of the route help more than adjectives do, and an OTDR trace plus per-unit IL/RL data close the acceptance argument. Need the jacket logic checked for your route? Send BWNFiber your fiber count, installation method, and application scenario and we will map it to the right assembly.
TPU and LSZH in the ODC jumper series
The jacket decision lands on a specific assembly. BWNFiber’s outdoor ODC jumper series is where the TPU and LSZH jacket options become orderable products. Start from the family overview, then pick the series your route calls for. Across the series, the jacket line reads LSZH/TPU in black, working and storage is rated −20 °C to +70 °C, and armored or unarmored builds are available:
- ODC-2C / ODC-4C series overview: ODC-2C & ODC-4C outdoor waterproof fiber jumper
- ODC-2C assemblies: ODC-2C ME patch cord, ODC-2C MP fiber patch cable jumper, ODC-2C FSS patch cable, ODC-2C FSH fiber jumper
- ODC-4C assemblies: ODC-4C MP cable assembly, ODC-4C ME FTTA patch cord, ODC-4C FSS fiber patch cord, ODC-4C FSH outdoor fiber cord
Whatever the series, the jacket follows the same per-segment rule: state it per segment on the build sheet, and the assembly matches the route.
How BWNFiber supports project-based cable selection
For ISP and FTTH projects, BWNFiber usually recommends confirming fiber count, cable structure, installation method, tensile strength, and local environmental conditions before production. This helps reduce mismatch risks during deployment.
On jacket-driven projects the same pre-production check runs against the exposure profile: UV and temperature range, oil or chemical contact, and the fire code at the building entry. Where a route crosses segments, hybrid builds with both jackets named and a stated transition point, plus other customized designs, are normal practice rather than exceptions.
The evidence trail this page describes is the same checklist a quote comes with: compound test reports (IEC 60754/61034/60332) behind LSZH claims, per-unit IL/RL data for assemblies, and datasheets that name the jacket and state tensile, crush, and bend radius values. OEM/ODM builds, bulk supply, and export orders are standard lines for project business. For export orders, the same documentation pack travels with the shipment, so customs and site acceptance run off the same numbers.
Ask BWNFiber for a project-based cable recommendation when the route crosses segments or the spec is still open. For the numbers, request a fiber optic cable specification sheet.
Frequently asked questions
Is TPU better than LSZH for outdoor fiber cable?
Mechanically, yes: TPU wins on abrasion, flex life, and low-temperature handling. But “outdoor” is not the only question. If the run enters occupied or enclosed space, fire behavior rules the decision, and LSZH (or an equivalent fire rating) wins there.
Is LSZH cable suitable for outdoor use?
Outdoor-grade LSZH formulations handle UV and weather, and LSZH jumpers are common where runs enter buildings. For long-term exposed tower service with abrasion and flex, TPU outlasts it mechanically.
Does TPU contain halogens?
Formulation-dependent. Polyurethane jackets are not automatically halogen-free; if the specification requires halogen-free, state it explicitly rather than inferring it from “TPU.”
What standards prove a jacket is really LSZH?
Three IEC test families: IEC 60754-1/-2 for halogen acid gas and acidity, IEC 61034 for smoke density, and IEC 60332 for flame retardance. Ask for reports on the jacket compound, and note that in North America the NEC’s OFNP/OFNR listings are a separate framework from the LSZH concept.
What jacket do FTTA tower jumpers usually use?
TPU is the common default for exposed tower runs. Where the jumper continues into an occupied shelter or equipment room, LSZH builds are specified. Many projects use both, per link segment.
Can one assembly combine TPU and LSZH sections?
Yes. Hybrid builds run TPU on the exposed outdoor section and LSZH from the building entry inward, transitioned at a closure or entry cabinet. State both jackets and the transition point in the BOM.
Can I get an armored cable with an LSZH jacket?
Yes. Armor is a layer under the jacket, and the outer jacket can be TPU, LSZH, or PE. Armor for the mechanical threat, jacket for the environment and code.
Is PUR the same as TPU?
In cable-jacket practice, yes. PUR and TPU both refer to the polyurethane jacket family; datasheets from different vendors use either name.
What about TPU vs PE for outdoor runs?
Different jobs. A tower jumper in PE would be unusually stiff to work with; a buried feeder in TPU would be money spent on the wrong strengths. PE earns its place on long, static duct and burial runs; TPU earns its keep where the cable is exposed and handled.
What jacket for direct burial?
PE, usually over armor: moisture-proof and economical at feeder lengths. Direct burial is feeder territory, not jumper territory; the cable class changes, not just the jacket.
Is TPU more expensive than LSZH?
On raw material, yes; TPU carries the higher jacket cost. At assembly level the difference is modest next to the cost of the link, and minor next to the cost of replacing a jacket that fails in service.
Does jacket choice affect optical performance?
No. Attenuation and loss live in the fiber and connectors. Jacket choice affects how long the cable survives the environment, which is what keeps that optical performance intact over years.
Is LSZH the same as PVC?
No. PVC contains chlorine, a halogen; when it burns it releases dense smoke and corrosive hydrogen chloride gas. LSZH compounds remove halogens from the formulation, which is the point of the category. PVC still has its place in ordinary indoor patching where no fire specification applies; for the full PVC vs LSZH vs PE landscape, see the jacket guide’s material map.
How do I compare suppliers on the same jacket?
Send every supplier the same six questions from the RFQ section and compare the documents that come back: a datasheet that names the jacket (TPU / LSZH / PE) with tensile, crush, and bend radius values; compound test reports for any LSZH claim; and a sample assembly you can approve before the bulk run. Suppliers who answer in adjectives instead of numbers or reports are not answering the question.
Which jacket does BWNFiber recommend for ODC jumpers?
TPU for exposed tower and industrial runs, LSZH for runs entering occupied space, with PE and armored options for feeder-style routes. Our ODC patch cables carry TPU and LSZH jackets in black, with armored or unarmored builds. Tell us your routing environment and we will match it.
The bottom line
The wrong jacket rarely fails on day one. It fails a few winters in, cracked on a tower or flagged in a fire inspection, at replacement cost. Exposure, flex, and abrasion call for TPU; people, codes, and enclosed space call for LSZH. Decide per route segment, state it in the BOM, and the jacket stops being a failure mode.
Not sure which segments your route has? Send BWNFiber the route description or photos. Jacket selection is part of the build sheet, and so is the test evidence behind it.
