{"id":31121,"date":"2026-09-28T06:07:00","date_gmt":"2026-09-28T06:07:00","guid":{"rendered":"https:\/\/doingcable.com\/?p=31121"},"modified":"2026-09-28T06:54:54","modified_gmt":"2026-09-28T06:54:54","slug":"what-is-low-smoke-halogen-free-cable","status":"publish","type":"post","link":"https:\/\/doingcable.com\/fr\/what-is-low-smoke-halogen-free-cable\/","title":{"rendered":"What is Low Smoke Halogen-free cable?"},"content":{"rendered":"

A low smoke halogen-free cable<\/a><\/strong> (LSZH \/ LS0H \/ LSOH \/ LSHF \/ HFFR) is a power, control or data cable whose insulation, bedding and sheath contain no added fluorine, chlorine or bromine<\/strong> and which, when burned under the specified tests, releases little visible smoke and little corrosive acid gas. The three tests that close the definition are IEC 60754-1\/-2<\/strong> (halogen acid and acidity), IEC 61034-2<\/strong> (3 m cube smoke, typically \u226560 %<\/strong> light transmittance) and a flame-spread clause \u2014 IEC 60332-1-2<\/strong> on a single cable and usually IEC 60332-3<\/strong> Category A\/B\/C on a bunch. The jacket compound on 0.6\/1 kV power cable is IEC 60502-1 type ST8<\/strong>, conductor temperature 90 \u00b0C<\/strong>. LSZH is a material system. It is not<\/strong> a CPR Euroclass and not a fire-resistance rating (IEC 60331 \/ BS 6387).<\/p>\n\n\n\n

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Constructions we supply \/ tool for<\/strong><\/p>\n\n\n\n

Taper<\/th>Typical build<\/th>Voltage<\/th>Jacket<\/th>Fire package<\/th><\/tr><\/thead>
LV power unarmoured<\/td>Cu\/XLPE\/LSZH<\/td>0.6\/1 kV<\/td>ST8<\/td>60332-1 + 61034 + 60754<\/td><\/tr>
LV power armoured<\/td>Cu\/XLPE\/LSZH\/SWA\/LSZH or AWA<\/td>0.6\/1 kV<\/td>ST8 both bedding and sheath<\/td>BS 6724 \/ IEC 60502-1<\/td><\/tr>
Building wire<\/td>H07Z-K \/ H05Z-K, EI5<\/td>450\/750 V<\/td>LSZH thermoset<\/td>EN 50525-3-21<\/td><\/tr>
Control \/ data<\/td>Cu\/LSZH or XLPE + LSZH sheath<\/td>300\/500 V<\/td>ST8 \/ HFFR<\/td>60332-3 Cat. C or A<\/td><\/tr>
Marine<\/td>IEC 60092 SHF1 \/ SHF2<\/td>0.6\/1\u20131.8\/3 kV<\/td>SHF1 TP \/ SHF2 XL<\/td>60092-353:2024<\/td><\/tr>
Rail<\/td>EN 45545-2 R15\/R16<\/td>rolling stock<\/td>LSZH<\/td>HL2 \/ HL3<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n

Conductor: IEC 60228 Class 2 or Class 5, plain or tinned. Insulation: XLPE or halogen-free EI5 \/ cross-linked polyolefin \u2014 not PVC. Colour: often black or grey RAL 7001; print must list the test numbers, not only \u201cLSZH\u201d. Send section, armour yes\/no, CPR class if EU building, rail HL if rolling stock.<\/p>\n\n\n\n

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What Is Low Smoke Halogen-Free Cable?<\/h1>\n\n\n\n

A low smoke halogen-free cable is a cable whose polymeric layers are formulated without halogenated flame retardants so that a fire produces little opaque smoke and little hydrogen halide, while still meeting a stated flame-spread test.<\/p>\n\n\n\n

PVC jackets contain chlorine. In fire they evolve dense smoke and HCl that attacks eyes, lungs and switchgear. LSZH compounds replace that chemistry with a polyolefin or EVA\/PE matrix loaded with aluminium trihydrate (ATH)<\/strong> ou magnesium hydroxide (MDH)<\/strong> at typically 50\u201365 %<\/strong> by weight. The hydrate decomposes endothermically, releases water vapour, dilutes fuel gas and leaves an oxide char. That is why smoke stays low and why there is no halogen acid to measure \u2014 provided the whole cable<\/strong>, including tapes and fillers, is halogen-free. A PVC-bedded \u201cLSZH sheath\u201d fails IEC 60754 on the complete sample. ICEA T-33-655-2023 states the same caution for jackets alone.<\/p>\n\n\n\n

Labels LSZH, LS0H, LSOH, LSHF, HFFR, FRNC, LSF<\/strong> are commercial synonyms. None of them is a fire class. The datasheet must name IEC 60754, IEC 61034, IEC 60332-x and, for EU buildings, the CPR declaration (B2ca \/ Cca \/ Dca + s1, d1, a1)<\/strong>. FRLS (flame-retardant low-smoke PVC) still contains halogen and is not LSZH.<\/p>\n\n\n\n

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How do LSZH, PVC, FRLS and XLPE-PVC jackets differ in a fire?<\/h2>\n\n\n\n

PVC and FRLS release halogen acid. LSZH does not. XLPE insulation is already halogen-free; the jacket decides the smoke and acid numbers unless the bedding is PVC.<\/p>\n\n\n\n

Propri\u00e9t\u00e9<\/th>PVC ST1\/ST2<\/th>FRLS PVC<\/th>LSZH \/ ST8 \/ HFFR<\/th><\/tr><\/thead>
Halogen in polymer<\/td>Yes (Cl)<\/td>Yes (Cl)<\/td>No added F\/Cl\/Br<\/td><\/tr>
IEC 60754-1 acid gas<\/td>~20\u201330 % HCl class<\/td>reduced but present<\/td>typically <0.5 %<\/strong> (ICEA HF <0.2 %<\/strong>)<\/td><\/tr>
IEC 60754-2<\/td>pH low, high conductivity<\/td>improved vs PVC<\/td>pH >4.3<\/strong>, low conductivity<\/td><\/tr>
IEC 61034-2 transmittance<\/td>often <20\u201340 %<\/td>medium<\/td>commonly \u226560 %<\/strong><\/td><\/tr>
Conductor temp (60502-1)<\/td>ST1 80 \u00b0C \/ ST2 90 \u00b0C<\/td>70\u201390 \u00b0C<\/td>ST8 90 \u00b0C<\/strong><\/td><\/tr>
Abrasion \/ tear<\/td>good<\/td>good<\/td>lower unless XL<\/td><\/tr>
Cost index<\/td>1.0<\/td>~1.1\u20131.3<\/td>~1.3\u20132.0<\/td><\/tr>
CPR typical<\/td>Eca \/ Dca<\/td>Dca<\/td>Cca\u2013B2ca s1,d1,a1<\/strong> when designed<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n

IEC 60502-1:2021 Table 4 lists ST8<\/strong> as the halogen-free thermoplastic sheath at 90 \u00b0C<\/strong>. The 2021 edition added ST8 mechanical language that older 2004 sheets do not carry. BS 6724 is the UK armoured LSZH counterpart to PVC BS 5467. EN 50525-3-11 \/ 3-21 \/ 3-31 cover 450\/750 V halogen-free building wires still listed under the LVD harmonised set in 2025.<\/p>\n\n\n\n

Flame-resistant<\/strong> (circuit integrity, IEC 60331 or BS 6387) is a mica-tape or MI construction. An LSZH jacket does not keep the circuit alive. Specify both if the emergency circuit requires it: e.g. Cu\/Mica\/XLPE\/LSZH.<\/p>\n\n\n\n

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Where must LSZH be specified \u2014 and where is PVC still acceptable?<\/h2>\n\n\n\n

Specify LSZH wherever people must evacuate through the same volume as the burning cable: tunnels, metros, hospitals, data halls, high-rise risers, ships and rolling stock. PVC remains acceptable on outdoor overhead and many industrial trays where smoke is not the design constraint.<\/p>\n\n\n\n

Mandatory or de-facto LSZH<\/strong><\/p>\n\n\n\n