Rail and metro wiring

Underground and enclosed transit infrastructure mandates IS 17048:2018 LSZH throughout occupied and public areas because tunnel and station fires are confined-space scenarios. Halogen-free construction (HCl < 0.5%) prevents toxic acid gas; high smoke transmittance (≥ 70%) preserves passenger evacuation visibility.

DMRC and equivalent Indian Railways underground specifications mandate LSZH; substituting FR or FR-LSH in an underground occupied area fails the fire-strategy review at commissioning.

DMRC and Indian Railways require IEC 60332-3-24:2018 Category C evidence — bunched cable flame-spread limit of 1.5 L/m fuel — submitted alongside the single-cable test data per IEC 60332-1-2:2004.

National Cables' IS 17048:2018 cables are tested to this standard; type-test reports are issued for tender submission with the BIS licence reference (CM/L-8800227819). Category C is the appropriate level for grouped cables in dense station and tunnel tray installations.

BT CW1308 governs station PABX, internal voice, and admin telephone distribution. CW1308 specifies:

• Solid bare annealed copper conductor (IEC 60228 Class 1)
• Maximum loop resistance 97.8 Ω/km
• Working voltage 80 V (signalling level, not power)
• Operating temperature range 0–70°C

For high-performance signal and data backbone, specify CW1293 (BT CW 1293 Issue 4) with tinned solid copper and TI54 insulation — used in data centres and exchange-MDF distribution.

No. Surface station buildings — administrative blocks, ticketing, parking — follow NBC 2016 Part 4 like other above-ground occupancies. Group D (assembly, Cl. 4.15) or Group E (business, Cl. 4.16) typically applies, requiring FR-LSH minimum.

Underground stations and enclosed tunnels require LSZH (IS 17048:2018) for the toxic-gas and smoke-density reasons specific to confined-space fires. Surface buildings can meet NBC compliance with FR-LSH at lower per-metre cost; underground zones require the zero-halogen standard.

Yes. H07Z-K (EN 50525-3-41) is the international harmonised designation for LSZH single-core flexible wire — same zero-halogen, 90°C LSH1 thermoplastic construction produced on the IS 17048:2018 certified line.

This enables seamless specification on cross-border metro and rail projects in GCC, African, and emerging-market transit systems. Type-test reports are issued in international tender format with the BIS licence reference.