Rail and metro wiring

NBCS 2026 (SP 7:2026) Part F Annex H-8.4 calls for fire-resistant/fire-survival LSZH armoured XLPE cable for fire and life safety equipment at enclosed metro stations. The same annex calls for flame retardant LSZH armoured XLPE cable for other essential services at enclosed stations. At open stations, it calls for flame retardant, low smoke halogen free (FRLSH) armoured XLPE cable for power supply. Annex H-9(c) calls for fire-resistant LSZH wires for emergency lighting at underground stations.

Specify IS 17048:2018 LSZH (HCl ≤ 0.5%, light transmittance ≥ 70%) where the project specification limits halogen acid gas to 0.5%. Fire-survival capability is a separate requirement from IS 17048:2018.

Metro tenders typically call for 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 supplies IS 17048:2018 type-test documentation (smoke transmittance, halogen emission, IEC 60332-1-2 single-cable flame test) with the BIS licence reference (CM/L-8800227819); state bunched-test (IEC 60332-3-24) requirements at the enquiry stage. Category C is the level tenders typically call for 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.

Not necessarily. NBCS 2026 Part F Annex H-8.4 calls for flame retardant, low smoke halogen free (FRLSH) armoured XLPE cable for power supply at open stations, and LSZH armoured XLPE cable at enclosed stations. NBC 2016 does not set cable type by occupancy group. NBCS 2026 FRLSH is halogen free and differs from IS 694:2010 FR-LSH, which permits up to 20% halogen acid gas. Specify FR-LSH (IS 694:2010) for surface administrative, ticketing, and parking buildings only where the project specification permits it.

Specify LSZH (IS 17048:2018) for underground stations and enclosed tunnels where the project specification limits halogen acid gas to 0.5%. FR-LSH has a lower per-metre cost than LSZH.

Yes. H07Z1-K (EN 50525-3-31) is the international harmonised designation for LSZH single-core flexible wire — same zero-halogen, 70°C thermoplastic HFFR construction (HFI-TP 70) 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.