FR-LSH vs
LSZH.
FR-LSH (FRLSH) stands for Flame Retardant Low Smoke and Halogen: a low-halogen PVC wire under IS 694:2010, limited to 20% halogen acid gas and a 60% smoke density rating. LSZH stands for Low Smoke Zero Halogen; its BIS designation is HFFR, Halogen-Free Flame Retardant, under IS 17048:2018: a non-PVC polyolefin wire limited to 0.5% halogen acid gas, with light transmittance ≥ 70% and Oxygen Index ≥ 31. The permitted halogen limits differ 40-fold, the standards differ, and the BIS licences are separate — the two are not interchangeable.
The two types — at a glance.
What each standard actually requires.
| Property | FR-LSH | LSZH / HFFR |
|---|---|---|
| Standard | IS 694:2010 (FR-LSH category) | IS 17048:2018 |
| Insulation | PVC (low-smoke, low-halogen compound) | Non-PVC polyolefin — no chlorine or bromine |
| Halogen acid gas | ≤ 20% by weight — IS 10810 (Part 59) | ≤ 0.5% — IS 10810 (Part 59) |
| Combustion gas acidity | Not specified | pH ≥ 4.3, conductivity ≤ 10 µS/mm (Annex D) |
| Smoke test | Smoke density rating ≤ 60% — IS 13360 (Part 6/Sec 9) | Light transmittance ≥ 70% — IS 10810 (Part 63) |
| Oxygen Index | ≥ 29% | ≥ 31 |
| Temperature Index | ≥ 250°C | ≥ 250°C |
| Conductor temperature | 70°C | 70°C — thermoplastic (HFI-TP 70) |
| BIS licence | CM/L 8800140116 | CM/L 8800227819 |
Selection guidance.
FR-LSH is the common escape-route and high-occupancy specification — National Cables suggests it for stairwells and all areas of high-rise residential buildings. LSZH/HFFR is specified where the project limits halogen acid gas to 0.5%: underground metro stations, data centres, and hospital tenders commonly carry that condition, because hydrogen chloride corrodes medical and electronic equipment even at sub-ignition temperatures.
Specify by product — the National Cables range.
FR-LSH Single Core Wire — flame retardant, low smoke and halogen, IS 694:2010. LSZH / HFFR Wire — halogen-free flame retardant, IS 17048:2018. All ranges use Class 5 conductors — strand construction and resistance limits: IEC 60228 / IS 8130:2013 conductor classes. Size selection for a given load: cable size calculator.
Related comparisons: FR vs FR-LSH · FR vs LSZH · full three-way comparison.
FR-LSH vs LSZH — selection questions.
Low-halogen PVC versus halogen-free polyolefin, and why the two specifications are not interchangeable.
Is FR-LSH the same as LSZH?
No. Both are flame retardant, but the halogen limits are not interchangeable: FR-LSH permits up to 20% halogen acid gas per IS 694:2010, while HFFR permits up to 0.5% per IS 17048:2018 — a 40-fold difference in the permitted limit. The insulation chemistry also differs: FR-LSH is PVC-based; HFFR contains no chlorine or bromine.
What are the full forms of FRLSH, FRLSZH, and HFFR?
FRLSH (FR-LSH): Flame Retardant Low Smoke and Halogen — IS 694:2010. FRLSZH (FR-LSZH): Flame Retardant Low Smoke Zero Halogen — a trade name for the LSZH category. HFFR: Halogen-Free Flame Retardant — the designation used by IS 17048:2018.
How do the smoke tests differ between FR-LSH and LSZH?
The two standards use different smoke tests. FR-LSH: smoke density rating ≤ 60% per IS 13360 (Part 6/Sec 9), under IS 694:2010. HFFR: light transmittance ≥ 70% per IS 10810 (Part 63), under IS 17048:2018. The methods differ, so the two figures are not directly comparable.
A hospital BOQ names IS 17048:2018 — does FR-LSH comply?
No. Where a specification names IS 17048:2018, FR-LSH to IS 694:2010 does not meet it — the halogen limits differ 40-fold and the BIS licences are separate. Specify HFFR to IS 17048:2018 where the project specification limits halogen acid gas to 0.5%.
Do FR-LSH and LSZH have the same conductor temperature rating?
Yes, in the National Cables range: both are rated 70°C continuous. IS 17048:2018 rates thermoplastic HFFR insulation (HFI-TP 70) at 70°C; the 90°C rating applies only to crosslinked HFFR compounds.
Specify the correct cable for your project.
Our technical team matches IS 694:2010 and IS 17048:2018 cable types to your project specification.