BIS STANDARD REFERENCE · IS 7098
IS 7098 Parts 1–3 — XLPE-insulated cables (LV up to 1100 V · MV 3.3–33 kV · EHV 66–220 kV)
What is IS 7098?
IS 7098 is the Bureau of Indian Standards specification for cross-linked polyethylene (XLPE) insulated cables. Published in three parts corresponding to voltage class:
- IS 7098 Part 1: XLPE cables for working voltages up to and including 1100 V (low voltage). The LV class, directly comparable to IS 1554 (PVC armoured) for sub-main feeders and outdoor distribution.
- IS 7098 Part 2: XLPE cables for working voltages 3.3 kV to 33 kV (medium voltage). The standard for 11 kV and 33 kV distribution feeders — the bulk of Indian utility and industrial HT cable procurement.
- IS 7098 Part 3: XLPE cables for working voltages 66 kV to 220 kV (extra-high voltage). EHV class used by state DISCOMs and power utilities for transmission projects.
Why XLPE instead of PVC insulation?
| Property | PVC (IS 694 / IS 1554) | XLPE (IS 7098) |
|---|---|---|
| Max conductor temperature | 70 °C (continuous) | 90 °C (continuous) |
| Short-circuit temperature | 160 °C | 250 °C |
| Dielectric strength | Lower | Higher — suits MV/HV applications |
| Moisture resistance | Moderate | High — suitable for direct burial at MV/HV |
| Weight | Heavier (PVC is denser) | Lighter per unit current-carrying capacity |
| Available voltage range | Up to 1100 V (IS 694 / IS 1554) | Up to 220 kV (IS 7098 Part 3) |
| Halogen content | High (PVC contains chlorine) | None — inherently halogen-free |
Scope: what products does IS 7098 cover?
- Single-core and multi-core cables — 1-core, 3-core, 3.5-core, 4-core configurations
- Conductor sizes: 16 mm² to 2500 mm² depending on part and voltage class
- Conductor class: Class 2 stranded (standard), Class 1 solid (small LV sizes)
- Armour: steel wire armour (SWA), steel tape armour (STA), or aluminium wire armour (AWA)
- Sheath: PVC outer sheath (standard) or HOFR, LSHF options
NBC 2016 / infrastructure applicability
- LV distribution (Part 1): Used as an alternative to IS 1554 for LT feeders where a higher operating temperature (90 °C vs 70 °C PVC) increases current-carrying capacity — particularly in long-run cable trays and cable tunnels.
- 11 kV / 33 kV distribution (Part 2): Standard for utility sub-station to consumer transformer connections, underground distribution networks of DISCOMs, and industrial HT receiving sub-stations.
- EHV projects (Part 3): Specified by PGCIL, state transmission utilities, and large infrastructure projects (metro rail, airports, data centres) for 66 kV, 132 kV, and 220 kV underground transmission links.
Key test methods under IS 7098 Parts 1–3
| Test | Method |
|---|---|
| Partial discharge (MV/EHV) | IS 10810 Part 52 / IEC 60502 — measured at 1.5 × U₀ voltage |
| Tan δ (dielectric loss) | ≤ 4 × 10⁻⁴ at 90 °C (Part 2/3) |
| Voltage withstand | 3.5 kV AC (Part 1); specific to voltage class in Parts 2 and 3 |
| Conductor resistance | Per IS 8130:2013 at 20 °C |
| Hot set (XLPE cross-link) | Elongation under load ≤ 175% at 200 °C per IEC 60811-507 |
| CPRI / ERDA type tests | Full type test including impulse voltage and bending required before production approval (MV/EHV) |
Third-party type testing
For IS 7098 Part 2 and Part 3 cables, procurement specifications (government tenders, DISCOM contracts) routinely require type-test certificates from CPRI (Central Power Research Institute), ERDA (Electrical Research and Development Association), or KEMA. These tests verify the cable's performance at the rated voltage class before it can be supplied under a BIS CM/L.
Frequently asked questions
What is the difference between IS 7098 Part 1 and IS 1554?
Both IS 7098 Part 1 (XLPE) and IS 1554 Part 1 (PVC) cover armoured power cables rated up to 1100 V. The key difference is insulation: XLPE allows a maximum conductor temperature of 90 °C (vs 70 °C for PVC), which increases current-carrying capacity for the same conductor cross-section. XLPE is also lighter per unit cable and inherently halogen-free. IS 7098 Part 1 XLPE is preferred for long cable runs, cable tunnels, and any installation where the higher operating temperature is an advantage.
What voltage does IS 7098 Part 2 cover?
IS 7098 Part 2 covers XLPE-insulated cables for medium voltage (MV) from 3.3 kV to 33 kV. In practice, 11 kV (U₀/U = 6.35/11 kV) and 33 kV (U₀/U = 19.05/33 kV) are the dominant voltage classes used in India for industrial HT connections and utility distribution feeders.
Which brands manufacture IS 7098 XLPE cables in India?
The major BIS-licensed IS 7098 manufacturers tracked on CablePriceIndia include: Finolex (Parts 1 & 2), Havells (Parts 1 & 2), KEI Industries (Parts 1, 2 & 3 up to 400 kV), National Cables (IS 7098), Polycab (Parts 1, 2 & 3 up to 220 kV), and RR Kabel (Parts 1 & 2 up to 33 kV). Lapp India manufactures to IEC standards rather than IS 7098. Verify each manufacturer's specific CM/L on manakonline.in for the voltage class required.
Is XLPE cable halogen-free?
Yes. XLPE (cross-linked polyethylene) insulation is inherently halogen-free — it contains no chlorine, bromine, or fluorine. The outer PVC sheath on IS 7098 cables does contain chlorine, but the sheath is a smaller portion of the overall cable by mass. For fully halogen-free cables (both insulation and sheath), specify IS 17048:2018 HFFR cable or IS 7098 XLPE with an LSHF outer sheath.
METHODOLOGY
Updated weekly by the cablepriceindia.com price-research desk. Last verified: 18 July 2026. Sources cited inline. We are an independent price-discovery service. Verify any BIS Conformity Marking Licence (CM/L) at bis.gov.in.