Flame Retardants for Wire and Cable: 6 FR Systems, Loading Levels and Selection

Flame retardants for wire and cable are mineral fillers, halogen-antimony systems and synergists, above all aluminium trihydrate (ATH) and magnesium hydroxide (MDH) at 160-180 phr in halogen-free compounds, that slow the spread of fire along cable insulation and sheaths. Each cable compound, from flexible PVC to LSZH polyolefin and XLPE, needs a different system and loading, so which flame retardant reaches which CPR class?

Flame retardants are the third-largest group of plastic additives by weight, and cable is one of the applications where they reach their highest loadings. This page works through why cable compounds burn without help, the 6 flame retardant systems used in wire and cable, whether a halogenated or halogen-free route fits a given compound, how much ATH, MDH, zinc borate, DEPAL or brominated system each cable type needs, how the loading changes extrusion and crosslinking, which fire tests and CPR Euroclasses each system reaches, which of these flame retardants carry a POP listing, an SVHC entry or a carcinogen classification, and which manufacturers supply cable-grade grades.

• 160-180 phr ATH or MDH in halogen-free (HFFR) cable, equal to about 61.5 wt% at 160 phr
• LOI target of at least 26% for flexible PVC cable insulation
• Regulation (EU) 2024/3110, the new Construction Products Regulation, has applied since 8 January 2026
• 6 flame retardant systems cover the entire cable market, from ATH and MDH to nanoclay synergists

Why Do Wire and Cable Compounds Need Flame Retardants?#

Wire and cable compounds need flame retardants because their base polymers burn easily and cables run in bundles and trays that carry fire from room to room. Polypropylene has a limiting oxygen index (LOI) near 17.5%, and unfilled EVA/LLDPE sheath compounds ignite at about 80 seconds and reach a peak heat release above 550 kW/m2 in a 35 kW/m2 cone calorimeter test. In the EU, permanently installed cables in buildings carry a mandatory CPR Euroclass, and in a 1988 US National Bureau of Standards study, flame-retarded cable products gave occupants more than 15 times longer escape time and released about one quarter of the heat of the non-retarded compound. The hub on flame retardants for plastics covers the same systems across every polymer, applied to films, moulded parts and profiles rather than to cable insulation and sheaths.

How does fire spread along a cable?#

Fire spreads along a cable when the flame heats the sheath until the polymer decomposes into combustible gases, which ignite and release enough heat to decompose the next section of sheath. Fire spreads along a cable in 4 steps.

1. Heating. An external flame or an adjacent burning cable raises the sheath surface temperature until the polymer begins to decompose.
2. Decomposition. The polymer breaks down into combustible gases; unfilled EVA/LLDPE reaches ignition at about 80 seconds under a 35 kW/m2 cone-calorimeter exposure.
3. Ignition and flame spread. The gases ignite, and the flame front advances along the cable run, tray or bundle, feeding on the next length of decomposing sheath.
4. Heat release and escalation. Peak heat release for an unfilled EVA/LLDPE compound exceeds 550 kW/m2, which is enough to ignite neighbouring cables in the same tray.

Halogenated flame retardants interrupt this sequence in the gas phase: hydrogen halide (HX) and antimony trihalide (SbX3) scavenge the H· and OH· radicals that keep the flame front burning, which is why halogen-antimony systems remain common in flexible PVC and automotive wire even where mineral fillers dominate elsewhere. The EU's harmonised cable test, EN 50399, measures flame spread distance, total heat release over 1,200 seconds (THR1200), peak heat release rate and the fire growth rate index (FIGRA) on a bunched-cable rig that reproduces this 4-step sequence at scale.

What makes a cable flame retardant?#

A flame-retardant cable is a cable whose insulation and sheath compounds contain enough flame retardant to stop a flame from travelling along it, which the single-cable test EN 60332-1-2 checks with a limit of 425 mm of damage for Euroclass Eca. Unlike a coating, the flame retardant is compounded into the polymer itself, at a level set by the target fire class and the base resin's own flammability. Rigid PVC resists burning on its own because of its chlorine content, but the plasticizer in flexible PVC cable compounds dilutes that effect and reintroduces the need for an added system. Three routes reach a flame-retardant cable compound.

• Halogen route: flexible PVC formulated with antimony trioxide, ATH and zinc borate, using the chlorine already present in the PVC resin.
• Halogen-free route: polyolefin or EVA sheaths filled with ATH or MDH at HFFR or LSZH loadings.
• Halogenated polyolefin route: brominated systems such as DBDPE or EBTBP combined with antimony trioxide, mainly in automotive wire.

What does LSZH mean for a cable compound?#

LSZH (low smoke zero halogen) describes a cable compound with no intentionally added chlorine or bromine that emits little smoke in a fire, usually a polyolefin or EVA sheath filled with about 60% aluminium trihydrate. HFFR, LS0H, LSOH and ZHFR are trade names for the same class of compound, alongside the further synonyms LSF, LSFH, NHFR, OHLS and HFT used across different cable-maker catalogues.

What Are the 6 Flame Retardant Systems Used in Wire and Cable?#

The 6 flame retardant systems used in wire and cable are metal hydroxides (ATH and MDH), carbonate and oxyhydroxide minerals, halogen-antimony systems, zinc borate and zinc stannates, phosphorus flame retardants, and nanoclay or char-barrier synergists, with ATH and MDH carrying most halogen-free cable. The systems are ordered here by their share of the cable market, from the metal hydroxides that fill most HFFR and LSZH compounds down to the barrier synergists that only reinforce another system's char layer. Gas-phase and condensed-phase action are explained in full detail under how flame retardants work, which applies across every polymer, not only cable.

1. Aluminium trihydrate (ATH) and magnesium hydroxide (MDH)#

ATH and MDH are metal hydroxide flame retardants that decompose endothermically in a fire, absorbing 1,051 J/g (ATH) or 1,316 J/g (MDH), releasing water vapour that dilutes the flame gases and leaving an oxide residue that adsorbs soot. ATH, 2Al(OH)3, converts to Al2O3 and 3H2O from about 200 °C and carries a theoretical loss on ignition of 34.6%. MDH, Mg(OH)2, converts to MgO and H2O and stays stable to about 320 °C, with a loss on ignition of 31.0%. Both mechanisms lower the concentration of combustible gas at the flame front while the solid oxide residue that remains on the sheath surface traps soot particles, which is the main reason HFFR and LSZH compounds produce less visible smoke than an unfilled polyolefin. Grades and particle sizes of the full family of mineral flame retardants (ATH and MDH) are compared across every plastics application on their page, not only cable.

A halogen-free cable sheath needs 160-180 phr of ATH or MDH to reach a usable fire class, a loading far higher than the single-digit phr levels typical of most other flame-retardant plastics.

ATH vs MDH in cable compounds#

ATH suits cable compounds processed below about 200 °C, such as EVA and LLDPE sheaths, while MDH suits compounds processed up to about 330 °C, such as polypropylene, because MDH releases its water about 110 °C later. This processing gap, not fire performance, is the main selection criterion between the two minerals at equal loading.

Huber, LKAB and Nabaltec product data. Boehmite's onset temperature of about 340 °C is unverified and left out of the table.

Identity and regulatory data for the mineral are on the substance page for aluminum trihydrate (ATH), including its CAS number and food-contact status.

Surface-treated ATH and MDH grades#

Surface-treated ATH and MDH grades carry a vinyl-silane, amino-silane or fatty-acid coating that bonds the filler to the polymer and restores the elongation at break that 160-180 phr of untreated mineral would destroy. Vinyl-silane coatings suit silane-crosslinked compounds, while amino-silane coatings suit thermoplastic HFFR sheaths; both coating types let compounders push loading higher without the brittleness that an uncoated mineral filler causes at the same phr. Vinyl-silane-coated Martinal grades appear at 180 phr in Huber's published XLPE examples, and coated MDH grades reach above 65 wt% in some polyolefin and elastomer compounds. Synthetic and natural brucite grades of magnesium hydroxide (MDH) are compared on their own substance page, including which grades carry a surface treatment.

The coating chemistry itself, and how it changes filler-polymer adhesion at high loadings, is explained in full under filler surface treatment, which applies to every filled compound, not only cable.

2. Huntite-hydromagnesite and boehmite#

Huntite-hydromagnesite is a natural carbonate mineral blend that releases water from about 220 °C and carbon dioxide from about 330 °C, which lets it work in halogen-free EVA, PE and PP cable compounds and leave a cement-like char at about 560 °C. The staged, two-step decomposition spreads the cooling and diluting effect over a wider temperature range than a single-step hydroxide, and the resulting char resists further heat penetration into the sheath. LKAB Minerals, which sells the mineral as UltraCarb, claims lower loadings than ATH or MDH in some systems but publishes no figure to support that claim. Decomposition stages and further loading data are detailed on the substance page for huntite hydromagnesite.

Boehmite (AlO(OH)) dehydrates at a higher temperature than ATH, which moves its main use into epoxy laminates and engineering thermoplastics rather than commodity cable sheaths; Nabaltec sells it as Apyral AOH and Actilox. Boehmite serves laminates more than cable, and our source library carries no cable loading data for it.

3. Halogen-antimony systems#

Halogen-antimony systems combine a chlorine or bromine source with antimony trioxide, which turns hydrogen halide into volatile antimony halides that trap the H· and OH· radicals feeding the flame. Antimony trioxide has no flame-retardant effect on its own; it reacts with the hydrogen halide released by the polymer to form antimony oxyhalide and then volatile antimony trihalide, which is the species that scavenges the radicals in the gas phase. The hazard profile of antimony trioxide is detailed on its own substance page, including its carcinogen classification.

In flexible PVC cable, the chlorine already present in the resin supplies the halogen half of the system, so a Huber reference formulation needs only 5 phr of antimony trioxide alongside 50 phr of ATH to reach its target fire class, well below the 160-180 phr that a halogen-free compound needs from the mineral filler alone.

Brominated polyolefin wire uses a separate additive to supply the halogen, since polyethylene and polypropylene contain none. DBDPE serves automotive wire and cable as a decaBDE replacement, and EBTBP (sold as Saytex BT-93) serves polyolefin wire and cable where UV stability and resistance to blooming to the surface matter. DBDPE and EBTBP belong to the brominated flame retardants page, which covers their use across every polymer, not only wire and cable.

4. Zinc borate and zinc stannates#

Zinc borate and the zinc stannates are synergists that cut smoke, afterglow and dripping in PVC cable: 3-6 phr of zinc borate next to ATH is the Huber guideline for flexible PVC. Zinc borate, sold as Firebrake ZB (2ZnO.3B2O3.3.5H2O, CAS 138265-88-0), forms a glassy borate layer above about 290 °C that promotes char formation, suppresses smoke and afterglow, and can partly replace antimony trioxide in a PVC formulation. Hydrate grades of zinc borate are compared on its own substance page. Suppliers self-classify zinc borate as Repr. 2 (H361d); it does not carry a harmonised CLP classification.

Zinc stannate, sold as Flamtard S, and zinc hydroxystannate, sold as Flamtard H (William Blythe), serve the same synergist role in PVC cable at 3-5 phr in research formulations; in those studies, zinc hydroxystannate can cut total smoke production by about 46-53%. Molybdates and stannates used as smoke suppressants across other polymer families are compared under that page.

5. Phosphorus flame retardants#

Phosphorus flame retardants reach cable in three forms: phosphinates such as DEPAL in TPU and TPE jackets, phosphate plasticizers in flexible PVC, and, in research, phosphate glasses that strengthen the char of ATH-filled sheaths. Aluminium diethylphosphinate (DEPAL, CAS 225789-38-8, 23.3-24.0 wt% phosphorus) decomposes above 300 °C and works alongside nitrogen synergists at 20-40 wt% in TPU and TPE cable jackets, per Clariant data cited in our research. DEPAL chemistry, its full grade range and its use outside cable are covered on phosphinate flame retardants.

Flexible PVC cable compounds can also use phosphate plasticizers as a route to flame retardancy, in place of or alongside a mineral filler. In a single 2025 study by Alsayed and coauthors, published in Polymers 17:2679, a phosphate low-melting glass at 10 wt% in a PE-EVA sheath already filled with ATH can lower the peak heat release rate to 142 kW/m2, a 52% reduction against the unmodified compound.

6. Nanoclay and char-barrier synergists#

Nanoclay and other char-barrier synergists do not flame-retard a cable compound on their own; they reinforce the oxide or char layer that ATH and MDH leave, so the burning sheath releases heat more slowly. Organoclay (montmorillonite-based), layered double hydroxides and carbon nanotubes each reduce peak heat release through this surface-barrier effect, but seldom pass a UL 94 flammability test without a primary flame retardant present. Dispersion and loading of nanoclay (organoclay) across filled compounds generally are covered on its own page. Li and coauthors, in a 2022 review in Polymers 14:2876 covering about 240 studies of halogen-free flame retardants for polyolefin cable sheath materials, place nanoclay and carbon nanotube synergists alongside ATH and MDH as the main halogen-free toolkit for cable sheath compounds.

Halogenated vs Halogen-Free Flame Retardants for Cable: Which to Choose?#

Halogen-free systems win wherever a cable must meet low-smoke and acidity classes such as s1a and a1, because burning halogens release acid gas, while halogen-antimony systems win where low loadings and flexible PVC processing matter more. The choice is rarely open once the target Euroclass or national wiring code sets the acidity and smoke requirement; the flame-retardant system follows from that requirement rather than the other way round. The full class of halogen-free flame retardants is covered site-wide on its own page, across every polymer that uses it, not only cable.

The 2012 findings of the EU FP7 ENFIRO project (grant 226563) rated ATH, MDH, DEPAL, APP, MPP, DOPO, zinc stannate and zinc hydroxystannate as flame retardants with good environmental and health profiles, which is one reason cable specifiers default to the mineral route wherever the target fire class allows the higher filler loading.

Which Flame Retardant Suits Each Cable Compound?#

The right flame retardant for a cable compound depends on its base polymer, its processing temperature and its target fire class: antimony trioxide, ATH and zinc borate for flexible PVC, ATH for EVA/LLDPE sheaths, MDH for polypropylene and DEPAL-based systems for TPU jackets. The table below sets out a reference formulation for each cable compound family, in the order flexible PVC, HFFR/LSZH polyolefin, XLPE, polypropylene, TPU/TPE and automotive wire.

Reference formulations from Huber, LKAB and Clariant literature; trials and the target CPR class decide the final loading.

Request quotes for cable-grade ATH, MDH, zinc borate or antimony trioxide directly from producers: specify the grade or CAS number, surface treatment, volume, cable compound and country. Download the Flame Retardant Selector Matrix, a PDF that cross-references polymer, target class, FR system and loading. Filter systems interactively by polymer in the flame retardant selector tool.

Flexible PVC insulation and sheath#

Flexible PVC cable compounds reach the usual LOI target of at least 26% with 45-100 phr ATH and 5 phr zinc borate, or with 5 phr antimony trioxide, because the chlorine in PVC already supplies the halogen. Huber's reference formulation combines PVC K70 (100 phr) with 55 phr DIDP plasticizer, 2.7 phr of a lead-free stabilizer, 45-100 phr ATH, 5 phr zinc borate and 10 phr chalk, and reaches an LOI of 26-27% with a UL 94 V-0 rating at 3 mm thickness. Ground calcium carbonate can add up to 70 phr as a secondary filler in the same class of formulation. Rigid and flexible PVC formulations, including the temperature classes 70, 90, 100/105 and 125 °C that a PVC cable insulation is rated to, are compared in full on flame retardants and smoke suppressants for PVC.

HFFR/LSZH polyolefin and EVA sheaths#

HFFR and LSZH sheaths are EVA or EVA/LLDPE blends filled with 160-180 phr ATH or MDH, and a higher vinyl acetate content (12-70% in cable grades) raises the LOI the filled compound reaches. Above about 40% vinyl acetate, EVA starts to behave like a rubber and needs a curing step of its own, separate from the flame-retardant loading. Huber's reference HFFR formulation pairs 160 phr ATH with a coupling-agent blend and an antioxidant package rather than the mineral alone, which the processing section below details. PE film and pipe grade formulations, which use a very different loading regime from cable sheaths, are compared on flame retardants for polyethylene.

Flame-retardant XLPE and silane-crosslinked compounds#

Flame-retardant XLPE uses vinyl-silane-coated ATH at about 180 phr, and the silane crosslinking route suits it because the compound is extruded below the temperature at which ATH starts to release water. Huber's published XLPE examples processing guidance states that the compound should only briefly exceed 200 °C, which keeps the extrusion step below ATH's onset of decomposition while the separate crosslinking step, driven by moisture and a tin catalyst, proceeds afterward at lower risk of premature water release. Peroxide, silane and e-beam crosslinking routes for XLPE (crosslinked polyethylene) for cable are compared in full on that page.

Polypropylene HFFR compounds#

Polypropylene HFFR compounds use MDH instead of ATH because PP is processed above ATH's 200 °C limit: 185.7 phr of coated MDH lifts PP from an LOI of about 17.5% to 30.2%. MDH loading in PP compounds can reach up to 65 wt% with coated grades, and MDH's stability to about 330 °C gives enough headroom above PP's typical melt-processing range. Intumescent and brominated systems used in other polypropylene applications are compared on flame retardants for polypropylene.

TPU and TPE cable jackets#

TPU and TPE cable jackets use phosphinate systems such as DEPAL with nitrogen synergists at 20-40 wt% to pass North American wire tests such as VW-1 and FT-4. Our source library carries no published test criteria for VW-1, FT-2 or FT-4; only the test names and the target loading range, sourced to Clariant data cited in our research, are established. Grades and test targets for flame retardants for TPU and TPE cable jackets are set out in full on that page.

Automotive and transportation wire#

Automotive and transportation wire still uses brominated flame retardants such as DBDPE and EBTBP with antimony trioxide, which replaced decaBDE in these polyolefin and elastomer insulations. DBDPE suits automotive wire and cable because it does not bloom to the surface and holds up under UV exposure, and EBTBP, sold as Saytex BT-93, serves the same role in polyolefin wire and cable. Our source library carries no phr loading figure for either substance in automotive wire, and no FMVSS 302 or EN 45545-2 cable-specific criteria; only the system names and their regulatory status are established. Rail and vehicle fire-test rules are set out on flame retardants for transportation.

How Much Flame Retardant Does a Cable Compound Need?#

A halogen-free cable compound needs 160-180 phr ATH or MDH (about 61.5 wt% at 160 phr), while a flexible PVC cable compound reaches its fire target with 45-100 phr ATH because PVC already contains chlorine. Four factors set the exact loading within those ranges.

• Target fire class, whether a CPR Euroclass or a North American test such as VW-1 or FT4, which fixes the minimum flame-retardant content.
• Base polymer and its LOI, since a more flammable resin such as polypropylene (LOI about 17.5%) needs more filler to reach the same class as a less flammable one.
• Processing temperature, which decides ATH versus MDH: ATH below about 200 °C, MDH up to about 330 °C.
• Required elongation and tensile strength after filling, which sets whether a coated or uncoated mineral grade is needed at a given loading.

Calculation example. Huber's reference HFFR sheath combines 67 phr EVA, 17 phr LLDPE, 16 phr of coupling agents and 160 phr ATH. The weight percent of ATH in the finished compound is 160 divided by (100 + 160), multiplied by 100, which equals 61.5 wt%, the figure Huber publishes for this formulation. Adding the 1.0 phr antioxidant package brings the total to 261 phr, which shifts the ATH share only slightly, to 61.3 wt%. Check the conversion for any other formulation with the PHR to weight percent calculator.

How Do Flame Retardants Change Cable Compound Processing?#

Flame retardants change cable compound processing in 2 ways: metal hydroxides cap the melt temperature, and loadings above 150 phr lower elongation and demand coupling agents and stabilizers. Both effects follow directly from the mechanism and the loading level set out in the two sections above, and a formulator has to plan for them before extrusion trials start, not after.

Processing temperature limits of ATH and MDH#

ATH limits cable compound processing to about 200 °C, the point where it starts to release water, whereas MDH stays stable to about 320 °C and allows processing about 110 °C hotter. This gap is the reason PP and other higher-temperature polyolefins default to MDH rather than ATH even where both would otherwise give equivalent fire performance at equal loading. For crosslinked polyethylene cured with dicumyl peroxide, the resin is melted at 120-140 °C and cured above 180 °C for about 5 minutes, a processing window that sits inside ATH's own temperature ceiling; our source library does not establish whether this proximity rules out ATH in peroxide-cured XLPE, so no such claim is made here.

Coupling agents, antioxidants and metal deactivators in filled cable compounds#

Filled cable compounds need 3 helpers besides the flame retardant: coupling agents (16 phr in the Huber HFFR recipe) that bond the mineral to the polymer, antioxidants (1.0 phr) and metal deactivators that stop copper from catalysing oxidation. Huber's HFFR reference formulation pairs 8 phr of Fusabond 226D with 8 phr of Lotader 3210 as the coupling-agent package, and 0.75 phr of Ethanox 310 with 0.25 phr of Ethaphos 368 as the antioxidant pair. Silane surface treatments on the mineral filler itself, covered earlier under ATH and MDH grades, restore the elongation that the coupling-agent package alone cannot fully recover at 160 phr and above. Maleated polyolefins and silanes used as coupling agents for filled and reinforced plastics generally are compared on that page.

Titanium, aluminium and copper conductors catalyse oxidation in a filled polyolefin compound, and wire and cable is the application where metal deactivators matter most, since the copper conductor sits in direct contact with the insulation. XLPE compounds commonly add a thio-phenol antioxidant such as Irganox 1035 together with a dedicated copper deactivator, Irganox MD 1024, at the copper interface. Copper-contact grades and dosage for metal deactivators across every polymer are set out on that page.

Which Fire Tests and CPR Classes Must Flame-Retardant Cables Pass?#

In the EU, permanently installed power, control and communication cables carry a Euroclass from Aca to Fca under the Construction Products Regulation, now Regulation (EU) 2024/3110, which has applied since 8 January 2026. The new CPR repeals the earlier Regulation (EU) 305/2011 that introduced cable Euroclasses in 2017, keeps cables in product family 31, and leaves EN 50575 in force as the harmonised standard until it is replaced. Test set-ups behind every class in the table below are explained in full under cable fire tests and CPR classes.

CPR Euroclasses and the flame retardant system each one needs#

The higher the Euroclass, the more flame retardant the cable compound needs: Eca only requires a single cable to stop burning within 425 mm, while B2ca limits a bunched-cable test to 1.5 m of flame spread and a peak heat release of 30 kW. Class B1ca, tested at 30 kW under EN 50399 together with the single-cable test EN 60332-1-2, sets the tightest limits: flame spread of 1.75 m or less, total heat release over 1,200 seconds (THR1200) of 10 MJ or less, peak heat release rate of 20 kW or less and a FIGRA index of 120 W/s or less. Aca and B1ca, together with B2ca, are assessed under Assessment and Verification of Constancy of Performance (AVCP) system 1+, the strictest third-party verification route in the CPR.

Limits from EN 13501-6, as republished by Erse Kablo. The "Typical FR system" column is an editorial mapping by PlasticAdditives.net, not part of the standard; the standard sets the fire-test limit, not the compound. Class Aca is omitted here because its heat-of-combustion limit is still being verified against a primary source.

Smoke, droplet and acidity classes (s, d, a)#

The additional classes rate smoke (s1 to s3), flaming droplets (d0 to d2) and acidity (a1 to a3), and the a1 limit of 2.5 microS/mm conductivity with a pH above 4.3 is the reason a class such as B2ca-s1a,d0,a1 requires a halogen-free compound. EN 61034-2 sets the smoke classes: s1 requires total smoke production (TSP1200) of 50 m2 or less and a peak smoke production rate of 0.25 m2/s or less, with s1a further requiring light transmittance of at least 80% and s1b requiring 60-80%; s2 allows up to 400 m2 TSP and 1.5 m2/s peak rate. EN 60754-2 sets the acidity classes: a1 requires conductivity below 2.5 microS/mm and pH above 4.3, while a2 allows conductivity up to 10 microS/mm at the same pH floor. The 3 m cube smoke-density method behind these classes is set out on smoke density testing (IEC 61034).

Because burning halogenated compounds release hydrogen chloride or hydrogen bromide, they cannot meet the a1 acidity limit, which is why a specification calling for B2ca-s1a,d0,a1 effectively rules out a PVC or brominated system and points a formulator to an HFFR ATH or MDH compound instead.

LOI, cone calorimeter and North American cable tests#

Compound developers screen cable formulations by limiting oxygen index (LOI) and cone calorimetry before they run cable tests, and a PVC cable compound usually has to reach an LOI of at least 26%. LOI is measured to ISO 4589-2 or ASTM D2863-23e1, and the same screening method shows the effect of a loading change directly, as in the HFFR polypropylene example above, where 185.7 phr of coated MDH lifts the LOI from about 17.5% to 30.2%. Cone calorimeter testing to ISO 5660-1 or ASTM E1354-26, most often run at 35 or 50 kW/m2 external heat flux, gives the peak and total heat release values that feed into cable-level classification work. Method and typical values for limiting oxygen index (LOI) are set out on that page, and heat-release curve interpretation is explained under cone calorimeter testing.

Outside the EU, cable makers reference a separate set of names: UL 1581 VW-1, UL 1685, CSA FT4 and FT6, IEC 60332-3 for bunched cables, IEC 61034 for smoke and IEC 60754 for acid gas. Our source library establishes only these test names for the North American and IEC bunched-cable standards, not their numeric pass/fail criteria, so no criteria are stated here.

Which Regulations Restrict Flame Retardants in Cables?#

Five flame retardants with a history in cable are restricted or under review in 2026: decaBDE and Dechlorane Plus as persistent organic pollutants, MCCP with an adopted EU POPs listing, DBDPE as an SVHC, and antimony trioxide as a suspected carcinogen. The table below gives the instrument and date behind each status.

Every FR-specific rule is tracked in full on flame retardant regulations.

Brominated flame retardants in cable: decaBDE, DBDPE and EBTBP#

DecaBDE is no longer an option for new cable: it has been a Stockholm Convention persistent organic pollutant since 2017 and the EU limits it to 10 mg/kg as an unintentional trace, while its replacement DBDPE became an SVHC on 5 November 2025. The identity and use profile of DBDPE (decabromodiphenyl ethane) are detailed on its own substance page, including its SVHC entry. DBDPE itself carries no restriction; it is listed as a substance of very high concern, a step short of a use ban. Under the US Toxic Substances Control Act, decaBDE remains permitted in motor-vehicle replacement parts until end of service life or 2036, whichever comes first, and in nuclear-plant wire and cable until end of service life.

The EU's proposed restriction of aromatic brominated flame retardants, which would cover EBTBP alongside DBDPE, is still at an early stage: a restriction mandate issued 11 November 2025, a call for evidence running from 21 January to 18 March 2026, and a draft Annex XV dossier planned for December 2026. The full timeline is on EU restriction of aromatic brominated flame retardants.

Chlorinated flame retardants in cable: MCCP, SCCP and Dechlorane Plus#

MCCP, the chlorinated paraffin used as a secondary plasticizer in PVC cable, will be listed under the EU POPs Regulation from 16 December 2026 by an adopted delegated act, with a 2-year exemption for flexible PVC in construction wires and cables. Cable exemptions and the substance's full regulatory history are listed on MCCP (medium-chain chlorinated paraffins). The adopted regulation, Commission Delegated Regulation C(2026) 6262 of 11 September 2026, is not yet published in the Official Journal as of 22 September 2026, so it should be described as adopted rather than in force. A 2% limit applies for 2 years to PVC recovered from cable recycling, and medical and in-vitro diagnostic device cables carry an exemption of up to 5 years.

Short-chain chlorinated paraffins (SCCP) entered the Stockholm Convention's Annex A at COP-8 in 2017 and have been an SVHC since 28 October 2008, a longer regulatory history than MCCP's. Dechlorane Plus, restricted in wire and cable, carries an SVHC listing since 15 January 2018 and a Stockholm Convention listing from COP-11 in 2023; properties and its full regulatory status are on Dechlorane Plus. It now has a 1 mg/kg limit from 2028 under EU Delegated Regulation (EU) 2025/1930, in force since 15 October 2025, after a transitional unintentional trace contaminant limit of 1,000 mg/kg that runs until 15 April 2028. All the listed additives on this table are tracked in full under POPs in plastics.

Antimony trioxide, lead and RoHS in cable compounds#

Antimony trioxide remains legal in cable compounds but carries a harmonised Carc. 2 classification and an IARC Group 2A rating, which pushes PVC cable makers towards zinc borate and zinc stannates as partial replacements. The classification (H351) applies EU-wide under CLP, and the International Agency for Research on Cancer placed antimony trioxide in Group 2A in its 2022 Volume 131 monograph; California's Proposition 65 has listed it as a carcinogen since 1 October 1990. Antimony trioxide is not an SVHC. Deadlines for the separate REACH restriction on lead in PVC, entry 63 of Annex XVII under Regulation (EU) 2023/923, which set a limit below 0.1% from 29 November 2024 after the recovered flexible PVC derogation expired on 28 May 2025, are listed on lead in PVC.

The RoHS Directive limits polybrominated diphenyl ethers (PBDEs) to 0.1% in electrical and electronic equipment; a planned addition of TBBPA and MCCP to that list was dropped in 2024. PBDE limits and the substances RoHS restricts in electronic cable and wiring harnesses are explained under RoHS and plastic additives.

Who Supplies Flame Retardants for Wire and Cable?#

Cable-grade flame retardants come mainly from Huber Advanced Materials (Martinal ATH, Magnifin MDH), Nabaltec (Apyral), Kyowa (Kisuma), LKAB Minerals (UltraCarb), U.S. Borax (Firebrake), William Blythe (Flamtard) and, for brominated systems, Albemarle (Saytex). Huber completed its acquisition of Martinswerk from Albemarle on 1 February 2016, which brought the Martinal and Magnifin brand lines together with Huber's own Micral, Hydral, Vertex and Zerogen grades. Clariant supplies phosphinate systems under its Exolit brand and is expanding Exolit OP production at Daya Bay, due 5 June 2026. OxyChem supplies Dechlorane Plus, now a restricted, POP-listed chlorinated flame retardant rather than a growth product. Plants and grades for the wider flame retardant manufacturers and suppliers directory are listed in full there.

Buyers should compare mineral grades by particle size and surface treatment, not by brand name, since two suppliers' ATH grades at the same nominal loading can behave very differently in extrusion once particle size and coating are taken into account. Our source library carries no cable-grade pricing and does not include the SERP-visible compound makers Teknor Apex, AlphaGary, Aurora Materials or ATP Chemicals, since they are compounders rather than flame-retardant producers.

Request quotes for cable-grade ATH, MDH, zinc borate or antimony trioxide from these and other producers, specifying grade, surface treatment, volume and cable compound, through the plastic additive supplier finder.

What Other Additives Go into Wire and Cable Compounds?#

Wire and cable compounds need a full additive package in which flame retardants are one layer, next to plasticizers and heat stabilizers in PVC, crosslinking agents in XLPE, and antioxidants and metal deactivators in every polyolefin insulation. The complete package by cable type, including the additives outside the scope of this page, is set out on additives for wire and cable compounds.

Plasticizers and heat stabilizers for PVC cable#

PVC cable compounds combine the flame retardant with a low-volatility plasticizer such as DIDP (55 phr in the Huber recipe) and a lead-free heat stabilizer, matched to temperature classes from 70 to 125 °C. Since the REACH restriction on lead in PVC took effect, cable compounders have moved to lead-free stabilizer systems across every one of those temperature classes. Temperature-class matching for plasticizers for wire and cable is covered in full on that page, and lead-free systems for PVC cable are covered on stabilizers for PVC cables.

Crosslinking agents for XLPE cable#

XLPE cable insulation is crosslinked with a peroxide such as dicumyl peroxide, an SVHC since 27 June 2024, or with a silane, and must pass a hot-set test with at most 175% elongation. Raising the dicumyl peroxide dose from 1.4 to 2.0 phr raises gel content from 74.3% to 81.6% and cuts hot-set elongation from 300% to 80%, well inside the 175% ceiling set by IEC 60811-507, while XLPE cable typically operates at 90-105 °C in service. The SVHC notice for dicumyl peroxide is detailed on its own substance page.

Is a flame-retardant cable the same as a fire-resistant cable?#

No: a flame-retardant cable limits the spread of fire along its own length, which EN 60332 and EN 50399 test, while a fire-resistant cable is a different product class outside the scope of this page.

Is PVC cable flame retardant without additives?#

Rigid PVC resists burning because of its chlorine, but flexible PVC cable compounds need added flame retardants because 55 phr or more of plasticizer, as in the Huber reference recipe, dilutes the chlorine and adds fuel to the compound.

Which is better for fire safety, LSZH or PVC cable?#

LSZH cable is the better choice where a class such as B2ca-s1a,d0,a1 is required, because it passes the a1 acidity limit, while flame-retardant PVC reaches lower Euroclasses at lower filler levels.

Are flame retardants in cables toxic?#

The mineral flame retardants in LSZH cable, ATH and MDH, are not SVHCs, while three halogenated cable flame retardants (decaBDE, Dechlorane Plus, MCCP) are regulated as persistent organic pollutants. ATH has no harmonised CLP entry, and MDH is not classified in PubChem's aggregated notifications. Exposure studies on the halogenated substances are summarised in full under flame retardants and human health.

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