A safety-critical cable is judged on the worst ten minutes of its service life, not the average. Fire-resistant constructions must stay electrically continuous while the surrounding temperature passes 750 °C and the structure is being hosed down. Halogen-free compounds must burn without releasing acid gas that blinds an escape route or corrodes a switchboard two rooms away. Mining and shipboard cables must survive being dragged across rock or flexed for years in a salt-laden engine room. That behaviour is built into the construction — tape overlap, powder density, sheath compound — not printed onto a datasheet afterwards.
Voltcore Cable builds fire-resistant, LSZH, mining and marine ranges on the same 32 lines in Yixing, Jiangsu, with mica taping, copper tube drawing, aluminium tube welding and rubber compounding done in house. Each family is tested to the standard the buyer names at RFQ stage — BS 6387 C/W/Z, BS 8491, IEC 60331, EN 50200, EN 50575, IEC 60754, IEC 61034, MT 818 or IEC 60092 — and reference dimensions, weights and test reports are issued with the quotation rather than after the order is placed.
Fire resistant cable is defined by what it does during a fire, not after it: the circuit stays energised while the flame is applied. That behaviour comes from an inorganic barrier — mica tape, magnesium oxide, a ceramic-forming compound — placed where a polymer would otherwise disappear. The standards differ in how harshly they test it: BS 6387 splits survival into fire alone (C), fire with water spray (W) and fire with mechanical shock (Z); BS 8491 applies all three at once; EN 50200 grades by duration as PH30 to PH120; GB/T 19216.21 holds 750 °C for 90 minutes with rated voltage applied.
See all 4 Fire Resistant Cable constructions →
Halogen-free cable exists because of what a fire does after the flame is out. PVC sheathing contains chlorine: burning it releases hydrogen chloride, which meets water vapour and becomes hydrochloric acid that attacks switchgear contacts, copper busbars, relay boards and the concrete around them, often causing more loss than the fire itself. It also produces dense smoke that removes visibility in an escape corridor within a minute. Replacing chlorine with a polyolefin compound loaded with aluminium or magnesium hydroxide removes both problems, at the cost of a stiffer compound that has to be extruded more carefully.
See all 4 LSZH / Halogen Free Cable constructions →
Underground mining cable is selected on mechanical duty first. A trailing cable behind a shearer is dragged over broken rock, pulled under machinery, wound onto a reel under tension and flexed hundreds of times a shift; its conductor is the last thing to fail. What ends service is sheath tear, crushed cores at a tight bend, strand fatigue where the cable enters a gland, or a sheath swollen by hydraulic oil and cutting emulsion. Conductivity is a solved problem at these sizes.
See all 3 Mining Cable constructions →
Shipboard and offshore cable is built around three conditions that land cable never meets: salt-laden humidity that corrodes a conductor under a crimp, continuous vibration that works a termination loose, and hydrocarbon exposure from fuel, hydraulic oil or drilling mud that swells an ordinary sheath. IEC 60092 is written for those conditions and is split by function: part 350 covers general construction and test methods, 353 covers power cables at 1 kV and 3 kV, 354 covers medium voltage, 359 covers sheathing compounds and 360 covers insulation compounds.
See all 4 Marine & Offshore Cable constructions →
The DC side of a photovoltaic array is the harshest low-voltage environment in a power plant. Cable lies on a hot roof or in desert gravel where the sheath surface passes 90 °C under full sun, it carries current continuously for six hours a day, and it is expected to do that for twenty-five years. EN 50618 and its IEC equivalent IEC 62930 were written for exactly that combination of heat, UV, ozone and DC voltage, and they test for it rather than assume it.
See all 4 Solar PV & EV Charging Cable constructions →
Rubber does what PVC cannot. A PVC-sheathed cable stiffens below 0 °C and cracks after a season of ozone exposure; an elastomeric sheath stays workable from −25 °C to +60 °C, absorbs the tug of a hand-held tool, and survives the sparks at a welding clamp. The trade is that rubber compound costs more per metre and has to be specified by compound type, not only by size.
See all 5 Rubber Flexible Cable & Welding Cable constructions →
Selection notes — Special Cable
Fire resistant or fire retardant — which one does the drawing actually need?
Fire resistant cable is tested with the circuit energised: the sample carries rated voltage while a flame at 750–950 °C is applied, and it passes only if no fuse blows and no conductor breaks. Fire retardant cable is tested for flame propagation only — a bundle is ignited and must self-extinguish within a defined length. One keeps equipment running through the fire; the other stops a cable tray from becoming a fuse.
Choosing wrongly is the most common error in a safety-cable RFQ. A smoke-extraction fan fed with flame-retardant cable stops as soon as the sheath burns off, usually within minutes of flame contact. Essential services — fire pumps, evacuation lifts, emergency lighting, fire alarms, public-address systems, emergency shutdown valves — need circuit integrity. General power and lighting in the same building usually need only flame retardance, and mixing the two correctly is where cost is saved.
- Fire resistant: BS 6387, BS 8491, IEC 60331, EN 50200 or GB/T 19216, voltage applied during the fire
- Fire retardant: IEC 60332-1 (single cable) or IEC 60332-3-22/23/24 (bunched, categories A/B/C/D)
- Ask for the test report, not the label — 'fire rated' appears on flame-retardant datasheets too
- Combine them by route: fire resistant in the riser, flame retardant on floor distribution
How environmental duty kills a cable before its conductor does
In harsh environments the electrical design is rarely the limiting factor. A mining trailing cable is dragged over sharp rock, run over by machinery, wound onto a reel under tension and flexed thousands of times per shift; what fails is sheath tear, core-to-core crush or conductor strand fatigue at the gland. A shipboard cable fails from oil swelling the sheath, vibration working a termination loose, or moisture reaching a screen.
Specify the mechanical duty alongside the voltage: minimum bending radius, permitted tensile load on the conductor during pulling, bend-cycle or flex-cycle class, tear and abrasion resistance of the sheath compound, oil and drilling-mud resistance, ozone and UV exposure, and the ambient range. Voltcore quotes all of these, because a cable that meets the electrical standard but fails the duty cycle is the expensive kind of failure.
- State bending radius as a multiple of overall diameter, and whether it applies to one bend or repeated flexing
- For reeling and trailing duty, give the reel diameter, pull tension and cycles per shift
- For offshore, name the sheath compound requirement: SHF2 MUD-resistant and the fluid it must resist
- For fire circuits, name the integrity duration that matches the evacuation or shutdown strategy
Reading a halogen-free specification: Euroclass, smoke and acid gas
Two different languages are used for the same intent. EN 50575 classifies construction products by reaction to fire — Dca-s2,d2,a1, Cca-s1,d1,a1, B2ca-s1,d1,a1 — and that class is what a CE mark and declaration of performance must state for cable sold into the EU. IEC 60754 and IEC 61034 describe the material behaviour: halogen acid gas evolved, pH and conductivity of the dissolved gas, and smoke density measured as light transmittance.
A specification that quotes only 'low smoke zero halogen' is incomplete. Give the Euroclass where the installation is in the EU or follows EN, and give the numeric limits where it does not: IEC 60754-1 acid gas not more than 5 mg/g, IEC 60754-2 pH not below 4.3 and conductivity not above 10 µS/mm, IEC 61034-2 light transmittance not below 60%. Voltcore states measured values for each compound rather than repeating the pass limit.
- B2ca-s1,d1,a1 — highest reaction-to-fire class, for escape routes in high-risk buildings
- Cca-s1,d1,a1 — common requirement for hospitals, schools and transport hubs
- Dca-s2,d2,a1 — minimum class normally accepted for general building installation in the EU
- Acidity and smoke figures matter in tunnels and offshore modules where dilution is impossible
What to send with an RFQ for safety-critical cable
Fire, mining and marine cable is quoted against a test protocol, not against a catalogue page. The RFQ should state the standard and the category or duration required, the voltage and core configuration, the cross-section range, the installation method (tray, conduit, direct burial, reel, trailing), the ambient and continuous conductor temperature, and whether terminations and glands are in scope.
Voltcore returns a quotation with a reference dimension and weight table, the applicable test report, the sheath and insulation compound identification, drum lengths and the cut-to-length option, and a stated lead time of 15–25 working days against a 500 m per size minimum. Samples up to 5 m are supplied free so the installation contractor can trial gland fit and bending before the order is released.
- Standard plus category or duration: e.g. BS 6387 CWZ, EN 50200 PH90, EN 50575 Cca-s1,d1,a1
- Core arrangement, including pilot, earth and control cores, and screening requirements
- Installation method, minimum bending radius and any reeling or trailing duty
- Termination scope: glands, seals, lugs, pre-cut lengths and drum labelling
Request pricing across the Special Cable range
Include cross-section, core count, voltage grade, route length and installation method — those five determine price more than anything else on the page.
- Engineer-reviewed before pricing
- Reference drawings issued with the quotation
- Free sample up to free sample up to 5 m