Cable is where flame retardancy gets judged hardest: not one test but four — flame propagation, smoke density, acid gas and sometimes circuit integrity — on a product that has to stay flexible, survive extrusion at tonnage, and last thirty years in a wall. We supply the mineral, synergist and compound layer of that problem.
Fig. WC01 — compounding at cable volumesCable runs in tonnage and certifies once. Batch consistency is the real requirement.
Most plastics carry a single flame rating. A cable specification typically stacks flame propagation, smoke density and acid gas emission — and for life-safety circuits, fire survival on top. Passing one while failing another is the normal failure mode, and the reason cable formulation looks nothing like enclosure formulation.
In tunnels, stairwells and plant rooms, dense smoke blinds escape routes long before the fire arrives. This is why LSZH exists as a material class and why smoke density is often the clause that decides the formulation.
Burning PVC releases hydrogen chloride, which corrodes switchgear and electronics that the fire never touched. In data centres and control rooms this is an asset-protection argument, not just a life-safety one.
Mineral hydroxides work thermally, not catalytically, so performance scales with quantity. At 55–65% filler the compound is more mineral than polymer — and elongation, tensile strength and line speed all have to survive that.
Cable fire testing splits by region and by what is being protected. These are not interchangeable, and a cable selling into both Europe and North America needs both routes.
| Standard | What It Tests | Typical Requirement |
|---|---|---|
| IEC 60332-1 | Single vertical wire, flame propagation | Baseline for most cable types |
| IEC 60332-3 | Bunched cables in a vertical tray — far harder | Categories A, B, C, D by fuel load |
| IEC 61034 | Smoke density (3 m cube) | ≥60% light transmittance |
| IEC 60754-1/-2 | Halogen acid gas content and pH/conductivity | <0.5% HCl equivalent for LSZH |
| IEC 60331 | Circuit integrity during fire | Fire resistant, not flame retardant — mica tape territory |
| EN 13501-6 / CPR | Euroclass for construction cables | B2ca-s1a,d1,a1 typical for demanding builds |
| NFPA 262 / UL 1666 | US plenum and riser burn tests | Earns CMP/CMR, OFNP/OFNR listings |
Two distinctions worth getting right before formulating: flame retardant is not fire resistant — the first slows spread, the second keeps the circuit alive, and they are achieved by completely different means (our article on fire resistant vs flame retardant cable covers this). And a US plenum listing is not an LSZH claim — most OFNP cable is fluoropolymer based, which is halogenated by definition; see OFNP vs LSZH.
Flame retardancy lives mostly in the jacket and insulation. Below is what each cable family typically needs — and where our supply stops.
| Cable Type | Compound | Usual System | Related Page |
|---|---|---|---|
| LSZH power & control cable | PE / EVA polyolefin | ATH or MDH at 55–65% + coupling agent | LSZH compounds |
| PVC power & building wire | Plasticized PVC | Sb₂O₃ or zinc synergist + ATH for smoke | FR PVC cable |
| Fibre optic cable | LSZH or PVC jacket | Mineral systems; tight particle control | FR fibre optic cable |
| EV charging & flexible cable | TPU, TPE, POE | Halogen-free packages; flexibility critical | FR TPU |
| XLPE insulated cable | Crosslinked PE | Mineral in jacket; insulation rarely filled | — |
| Fire survival cable | Mica tape + LSZH jacket | Barrier technology, not additive chemistry | Fire resistant vs FR |
Where our supply ends: we do not draw conductors, extrude cable, or produce mica tape, fluoropolymer insulation or silicone base compounds. We supply the flame retardant layer to cable makers and to the compounders who serve them — and where a project needs mica tape or FEP, we will say so rather than propose something adjacent.
The smoke and acid gas clauses eliminate most efficient gas-phase chemistry, which is why cable formulation is dominated by minerals and by synergists that clean up what halogen systems do badly.
MDH and ATH absorb heat, release water and leave an inert oxide layer. The cleanest smoke profile available, and the reason LSZH is possible at all.
PVC self-extinguishes on its own chlorine, so the work is smoke suppression and antimony reduction — zinc borate for lean-antimony packages, zinc stannate where antimony must go entirely.
Small additions that fix specific clauses — char sealing to help bunched-cable propagation tests, and drip control where the vertical test punishes flaming drops.
Nine inputs. With these we can propose a real system instead of a product list.
Cable certifies once and then runs for years. That puts batch consistency ahead of everything — a certificate earned on one lot has to hold for every lot after it.
Fig. WC02 — bench pre-screeningCheap screening before expensive cable-level testing.
Fig. WC03 — tonnage supplyBig bags and palletized delivery for cable volumes.Direct answers for technical and procurement teams in cable supply.
IEC 60332-1 (single wire) and 60332-3 (bunched) for propagation, IEC 61034 for smoke, IEC 60754 for acid gas, IEC 60331 for circuit integrity. Europe adds CPR Euroclasses for construction cable; North America uses NEC listings earned via NFPA 262 and UL 1666. A cable sold into both regions needs both test routes.
Because mineral hydroxides work thermally rather than catalytically — the cooling and water release scale with how much material is present. There is no low-loading version of this mechanism, which is why surface treatment and dispersion decide whether the compound still has usable elongation and tensile strength.
Partly. Surface-treated fine-particle grades, coupling agents and correct dispersion recover a large share of what high loading costs, and compound-form supply removes dispersion variability from your line. But some mechanical trade-off at 60% mineral is physics, not formulation skill — anyone promising none is overselling.
Usually not. Most OFNP and CMP cable achieves its rating with fluoropolymer or low-smoke PVC, both halogenated. If your specification requires halogen-free, it must be stated explicitly — “plenum rated” does not imply it.
Both. Powder additives for compounders with their own twin-screw capacity, masterbatch where dosing suits the line, and ready-to-extrude compound where you would rather run a single material stream. Which is cheaper per finished metre depends on your equipment and volume.
Tell us the standards and categories required, the destination market, your base polymer and jacket construction, and your mechanical targets. We will propose a system, pre-screen it in our burn lab, and say honestly what is achievable before you book cable-level testing.