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Product

Linear Heat Detection (LHD) Sensor CablesEN 54-28 / UL 52168 °C to 138 °C AlarmDigital LHD Sensor

SS-LD Digital Linear Heat Detection CableFixed-temperature digital linear heat detection sensor cable (68 °C / 85 °C / 105 °C / 138

SS-LD is a non-resettable digital linear heat detection (LHD) sensor cable per EN 54-28 and UL 521. Two high-tensile spring-steel sensing conductors are insulated with a calibrated heat-sensitive NTC/thermoplastic polymer that softens at its exact rated alarm

68–138 °C Calibrated

EN 54-28 / UL 521

Indoor / Tray LHD

Alarm Temp & Amb.

Order designation: SS-LD-78-PVC (78 °C Digital LHD)
Outer Ø ≈: 3.6 mm
Copper weight: 12 kg/km
Total weight ≈: 22 kg/km
Min. bend R: 54 mm

All sizes (12)

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Engineering reply in 2 business hoursCut-to-length export drumsEN 10204 3.1 certificate per drum

Alarm ratings: 68 / 85 / 105 /
Max. loop voltage: 42 VDC / 30 VAC
Sensing cores: 2 × spring steel
Loop resistance: ≈100 Ω/km
Ambient range: -40 to +105 °C
Min. bend radius: 50 mm (≈15×OD)

Typical values for this cable type, based on EN 54-28 / UL 521 — confirmed in the datasheet and quotation for your order.

Application fit

Is SS-LD right for your machine?

Provides continuous point-less thermal fire detection along cable trays, conveyor belts, escalators, warehouse racking, car parks and transformer bunds where dust or airflow defeats optical smoke detectors.

Fixed installation

Suitable

Clipped directly in sinusoidal waves along power cable trays, ceiling soffits and storage racks.

TBM gantry & advancing tunnel reel

Suitable

Detects localized hot-spots along tunnel cable troughs, escalators and conveyor galleries.

Switchgear & control cabinet wiring

Suitable

Routes inside HV/LV switchgear busbar chambers and battery storage cabinets.

Motorised monospiral reel

Not suitable

Spring-steel sensing twisted pair is for fixed detection clips only, not dynamic reeling.

SS-LDS braided LHD

Typical machinesPower cable trays & tunnelsBelt conveyors & bulk handlingCold stores & high-bay rackingSwitchgear & battery ESS cabinetsCar parks & road tunnels

Construction

Layer by layer

Two twisted high-tensile tinned/copper-clad spring-steel conductors under calibrated mechanical tension + calibrated heat-reactive polymer core insulation + flame-retardant PVC/LSZH outer sheath.

Schematic, not to scale — generated from the layer data

#	Layer	Material & reference
1	Spring-steel sensing conductors	Two twisted high-tensile tinned copper-clad spring-steel wires (0.8–0.9 mm Ø) held under radial contact tensionEN 54-28
2	Calibrated thermo-reactive polymer	Precision-extruded temperature-sensitive polymer dielectric that yields sharply at its rated alarm temperatureEN 54-28
3	Protective separation tape	Thin polyester protective binder tape over twisted sensing pairEN 54-28
4	Flame-retardant outer jacket	Moisture- and flame-retardant PVC or LSZH outer sheath (colour-coded by alarm temperature: Red, White, Orange, Blue)EN 54-28

SS-LD-68 (68 °C / 155 °F)

Max ambient +45 °C — general cable trays, offices, warehouses, escalators and cold-store ceilings (Red sheath).

SS-LD-85 (85 °C / 185 °F)

Max ambient +65 °C — warm plant rooms, solar roof voids, car parks and enclosed conveyors (White/Red sheath).

SS-LD-105 (105 °C / 221 °F)

Max ambient +85 °C — boiler houses, turbine hoods, transformer rooms and high-temp cable tunnels (Orange sheath).

SS-LD-138 (138 °C / 280 °F)

Max ambient +105 °C — industrial drying ovens, steam pipe proximity and steelworks galleries (Blue/Black sheath).

Technical data

Ratings & operating limits

Typical values: Typical values for this cable type, based on EN 54-28 / UL 521. Values for your order are confirmed in the datasheet and quotation.

Electrical

Max. operating voltage: 42 VDC / 30 VAC
Nominal conductor DC resistance: ≈100 Ω/km per core (200 Ω/km loop for distance location)
Dielectric withstand (untriggered): 500 VAC rms for 1 minute
Max. zone length: Up to 2000–3000 m per distance-locating controller zone

Thermal

Alarm temperature classes: 68 °C · 78 °C · 85 °C · 105 °C · 138 °C · 180 °C
Max. continuous ambient temp.: 45 °C (68 °C grade) · 65 °C (85 °C grade) · 85 °C (105 °C grade) · 105 °C (138 °C grade)
Min. operating temperature: -40 °C (-60 °C cold-store grade)

Mechanical

Nominal outer diameter: 3.6 mm ± 0.2 mm
Min. installation bend radius: 50 mm (≈15 × cable OD)
Recommended support clip spacing: 0.8 m to 1.2 m using insulated J-clips or Z-brackets

Resistance

Flame retardancy: IEC 60332-1-2 / UL 1581 VW-1
Humidity & dust immunity: IP67 sealed extruded sheath unaffected by dust or condensation

Reference standards

European product standard: EN 54-28 (Non-resettable line-type heat detectors)
North American standard: UL 521 / FM 3210

Identification

Sheath colour coding: Red (68/85 °C), White, Orange (105 °C) or Blue (138 °C)
Core polarity: Red & White/Black insulated spring-steel cores

Sizes

12 standard configurations (SS-LD)

Nominal dimensions, masses and electrical ratings for SS-LD according to EN 54-28 / UL 521.

Dimensions & masses
Designation	Alarm Temp & Amb.	Core Ø mm	Outer Ø ≈ mm	Copper kg/km	Total weight ≈ kg/km	Min. bend R fixed mm
SS-LD standard series
SS-LD-68-PVC (68 °C Digital LHD)	68 °C (Amb ≤45 °C)	2×0.85 mm	3.6	12	22	54
SS-LD-68-LSZH (68 °C LSZH LHD)	68 °C LSZH (Amb ≤45 °C)	2×0.85 mm	3.7	12	24	56
SS-LD-78-PVC (78 °C Digital LHD)	78 °C (Amb ≤55 °C)	2×0.85 mm	3.6	12	22	54
SS-LD-78-LSZH (78 °C LSZH LHD)	78 °C LSZH (Amb ≤55 °C)	2×0.85 mm	3.7	12	24	56
SS-LD-85-PVC (85 °C Digital LHD)	85 °C (Amb ≤65 °C)	2×0.85 mm	3.6	12	22	54
SS-LD-85-LSZH (85 °C LSZH LHD)	85 °C LSZH (Amb ≤65 °C)	2×0.85 mm	3.7	12	24	56
SS-LD-95-PVC (95 °C Digital LHD)	95 °C (Amb ≤70 °C)	2×0.85 mm	3.6	12	22	54
SS-LD-105-PVC (105 °C Digital LHD)	105 °C (Amb ≤85 °C)	2×0.85 mm	3.7	12	23	56
SS-LD-105-LSZH (105 °C LSZH LHD)	105 °C LSZH (Amb ≤85 °C)	2×0.85 mm	3.8	12	25	57
SS-LD-138-HT (138 °C Digital LHD)	138 °C (Amb ≤105 °C)	2×0.85 mm	3.8	12	26	57
SS-LD-180-HT (180 °C Fluoropolymer)	180 °C (Amb ≤150 °C)	2×0.85 mm	3.9	12	29	58
SS-LD-68-4C (Dual-Circuit 68 °C)	68 °C 4-Core Redundant	4×0.85 mm	5.2	24	42	78

Typical values for this cable type; dimensions and weights for your order are confirmed in the quotation.
Nominal outer diameters and weights are subject to manufacturing tolerances per EN 54-28 / UL 521.

Electrical data
Alarm Temp & Amb.	Max. DC R @ 20 °C Ω/km	Current in air A	Current in duct/tray A
68 °C (Amb ≤45 °C)	98.000	1	1
68 °C LSZH (Amb ≤45 °C)	98.000	1	1
78 °C (Amb ≤55 °C)	98.000	1	1
78 °C LSZH (Amb ≤55 °C)	98.000	1	1
85 °C (Amb ≤65 °C)	98.000	1	1
85 °C LSZH (Amb ≤65 °C)	98.000	1	1
95 °C (Amb ≤70 °C)	98.000	1	1
105 °C (Amb ≤85 °C)	98.000	1	1
105 °C LSZH (Amb ≤85 °C)	98.000	1	1
138 °C (Amb ≤105 °C)	98.000	1	1
180 °C (Amb ≤150 °C)	98.000	1	1
68 °C 4-Core Redundant	98.000	1	1

Current ratings apply at +30 °C ambient in free air and +25 °C in enclosed tray/conduit.

Quality & approvals

Testing & inspection

Routine tests on every production length, sample and type tests per batch — documented on an EN 10204 3.1 inspection certificate.

ConductorClass 5 stranding
Spark test100 % in-line
Lay-upCores, earth, fillers
SheathingInner, braid / screen, outer
Electrical testsAC voltage, resistance
DimensionsOD, wall thickness
Inspection documents & dispatchDrum & dispatch

Testing & inspection	Test value / reference	Frequency
Routine tests
500 VAC dielectric withstand & loop resistance calibration	No premature contact; calibrated Ω/km resistance within ±3 %	100 % of reels
Sample tests
Oven bath activation temperature accuracy test	Triggers strictly within rated temperature window per EN 54-28	Every production batch
EN 54-28 / UL 521 environmental & response-time qualification	Verified thermal response time across wind speeds and orientations	Type approval

Inspection certificate

Issued with every drum, listing the routine test results for that length.

Product approvals

EN 54-28 CompliantUL 521 / FM 3210 DesignIEC 60332-1-2 Flame RetardantRoHS 3 Compliant

Company certificates

ISO 9001ISO 14001ISO 45001VDE marks approvalUL / cULCE · LVD / EMC

Marking & supply

Ordering & delivery

Sheath marking

TEBAOFLEX SS-LD-85 DIGITAL LINEAR HEAT DETECTION CABLE 85C (185F) MAX AMB 65C EN 54-28 [meter mark]

Delivery form: Fumigated export wooden drums or shrink-wrapped coils
Standard drum lengths: 500 m · 1000 m standard drums (cut lengths on request)
MOQ: 100 m (stock sizes) · 300–500 m (production)
Lead time: 2–4 weeks ex-works
Incoterms: EXW, FOB, CIF, DAP

Technical documents

Downloads

PDFSS-LD Digital Linear Heat Detection Cable – technical datasheet12 sizes · construction, technical data, approvals XLSXSS-LD spec data (Excel)All 12 sizes with dimensions and data, for your BOM or quotation

Revision: 2026-10-20
Updated: 2026-10-20

FAQ

Questions engineers ask first

Not covered here? Send your drawing — an engineer replies within 2 business hours.

How does SS-LD digital linear heat detection cable locate the exact distance to a fire?

The two spring-steel sensing conductors have a calibrated DC resistance of approximately 100 Ω/km per core (200 Ω/km loop). When heat melts the polymer insulation at any point, the two conductors snap together into a hard short-circuit, and the LHD control module measures the loop resistance to display the exact distance in metres.

How do you choose the right alarm temperature grade (68 °C, 85 °C, 105 °C, 138 °C)?

Select the lowest alarm temperature whose maximum continuous ambient rating exceeds the highest expected peak ambient temperature at the installation location by at least 20 °C—for example, 68 °C for indoor cable trays (≤45 °C ambient) and 85 °C or 105 °C for solar-heated roofs or boiler rooms.

Is SS-LD resettable after a fire event?

No. SS-LD is a digital non-resettable sensor cable per EN 54-28. Once a thermal event fuses the two spring-steel conductors together, only the heat-damaged section is cut out and spliced with two weatherproof junction boxes and a replacement length of SS-LD.

When should SS-LDN or SS-LDS be selected instead of standard SS-LD?

Choose SS-LDN (PA12 nylon outer jacket) for outdoor UV exposure, chemical plants, oil mist or petrochemical tank rims; choose SS-LDS (AISI 304 stainless-steel wire braid) where rockfall, coal conveyors or rodent/mechanical abrasion could pinch the sensor cable.

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03Message for our engineers

SS-LD Digital Linear Heat Detection Cable

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Reel & motion:
- Reel type: 
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Datasheet Request a quote

SS-LD Digital Linear Heat Detection CableFixed-temperature digital linear heat detection sensor cable (68 °C / 85 °C / 105 °C / 138

Fixed installation

TBM gantry & advancing tunnel reel

Switchgear & control cabinet wiring

Motorised monospiral reel

SS-LD-68 (68 °C / 155 °F)

SS-LD-85 (85 °C / 185 °F)

SS-LD-105 (105 °C / 221 °F)

SS-LD-138 (138 °C / 280 °F)

Electrical

Thermal

Mechanical

Resistance

Reference standards

Identification

Inspection certificate

Product approvals

Company certificates

01Selected sizes

02Reel & motion

03Message for our engineers

SS-LDN Nylon LHD

SS-LDS Armoured LHD

Securiton SEC 15 / SEC 20

BS 7629-1 Standard 30 / Enhanced 120