N2XRY (Steel Wire Armour) cable generally offers superior overall corrosion resistance and structural durability compared to N2XBY (Steel Tape Armour) cable, particularly in aggressive soil chemistry and marine environments. Manufactured under [1]and BS 5467 standards, N2XRY utilizes heavy-gauge round galvanized steel wires that feature a lower surface-area-to-volume ratio and thicker protective zinc coating than the thin flat galvanized steel tapes used in N2XBY. Thin steel tapes are prone to rapid edge corrosion and pitting when moisture penetrates the PVC outer sheath, whereas heavy SWA wires retain structural load-bearing capacity much longer under corrosive ground conditions.
Technical Parameter & Corrosion Resistance Matrix
| Technical Parameter | N2XRY (Steel Wire Armour) | N2XBY (Steel Tape Armour) | Standard / Test Reference |
| Armour Layer Geometry | Heavy-gauge round galvanized steel wires | Thin flat helically-wrapped galvanized steel tapes | IEC 60502-1 / BS 5467 |
| Zinc Coating Surface-to-Volume Ratio | Low (Thick circular profile reduces corrosion speed) | High (Exposed edges accelerate zinc sacrifice) | BS EN 10244-2 (Galvanizing Class) |
| Pitting & Edge Corrosion Resistance | High (Uniform round surface resists localized pitting) | Moderate to Low (Slit tape edges expose bare steel) | ISO 9227 Salt Spray Corrosion Test |
| Moisture Trapping Risk | Low (Gaps between round wires allow drainage) | High (Helical tape overlaps trap acidic groundwater) | Underground Soil Corrosion Studies |
| Rated Voltage () | 0.6 / 1 kV | 0.6 / 1 kV | IEC 60502-1 |
| Conductor & Insulation | Annealed Copper / XLPE (90°C) | Annealed Copper / XLPE (90°C) | [2] / IEC 60502-1 |
| Primary Tensile / Mechanical Strength | High (Withstands longitudinal pull and soil shifting) | Low (Crush resistant only; low tensile strength) | Mechanical Load Limits |
| Recommended Harsh Environment | Marine zones, saline soils, high water tables, acidic soil | Dry soils, urban trenches, non-aggressive backfills | Direct Burial Suitability |
Metallurgy and Geometric Factors Influencing Corrosion Rates
1. Edge Corrosion and Zinc Galvanization Degradation
Steel tape armour used in N2XBY cables is slitted from wider galvanized steel sheets during manufacturing. This process leaves un-galvanized or thin-coated cut edges along the entire length of the tape. When groundwater or atmospheric moisture migrates through a damaged [3]outer sheath, [4]concentrates on these exposed edges. Conversely, N2XRY utilizes individual round steel wires that are fully galvanized continuously around their entire circumference pursuant to BS EN 10244-2, eliminating cut-edge vulnerability.
2. Crevice Corrosion in Overlapping Tape Structures
N2XBY relies on overlapping steel tapes to provide radial coverage. In moist or poorly drained underground installations, moisture enters the micro-gaps between the overlapping tapes through capillary action. Trapped water creates oxygen-depleted zones that trigger crevice corrosion and localized pitting, accelerating steel degradation. The cylindrical contact points of SWA wires minimize moisture entrapment and reduce crevice-induced failure risks.
Environmental Suitability & Long-Term Degradation Scenarios
Acidic, Saline, and High Water Table Soils (Specify N2XRY)
In coastal areas, estuaries, chemical industrial sites, or soils with low resistivity and high chloride/sulfate levels:
- N2XRY maintains structural shielding longer because the individual wire diameter (typically to ) requires significantly more time to corrode through compared to thin steel tapes ( to nominal thickness).
- For maximum chemical resistance in extreme soils, N2XRY can be specified with a High-Density Polyethylene (HDPE) or LSZH (Low Smoke Zero Halogen) oversheath to enhance moisture barrier performance over standard PVC.
Normal Urban Trenches and Well-Drained Earth (N2XBY STA Permissible)
- N2XBY performs adequately in dry, well-drained, neutral-pH soils where the PVC outer sheath remains completely intact.
- While STA offers excellent 100% surface coverage against rodent attack and crushing loads from static backfill, its lower corrosion allowance makes it unsuitable for waterlogged or chemically aggressive soil conditions without additional protective ducting.
CJDL CABLE Engineering Insight
For marine, saline or acidic ground conditions, we recommend specifying N2XRY — optionally with an HDPE or LSZH oversheath — since its heavy galvanized wires retain structural integrity where thin steel tapes corrode fastest. For dry, well-drained urban trenches, N2XBY remains a permissible choice.
References
[1] Wikipedia. IEC 60502[EB/OL]. 2026-09-29.
[2] Wikipedia. IEC 60228[EB/OL]. 2026-09-29.
[3] Wikipedia. Polyvinyl chloride[EB/OL]. 2026-09-29.
[4] Wikipedia. Galvanic corrosion[EB/OL]. 2026-09-29.