FR vs
FR-LSH.
FR stands for Flame Retardant; FR-LSH, also written FRLSH, stands for Flame Retardant Low Smoke and Halogen. Both are PVC wires under IS 694:2010 with identical flame retardance — Oxygen Index ≥ 29%, Temperature Index ≥ 250°C — and the same 70°C conductor temperature and 1100 V grade. The difference is two combustion limits FR does not have: FR-LSH must not exceed 20% halogen acid gas (IS 10810 Part 59) and a 60% smoke density rating (IS 13360 Part 6/Sec 9). Plain FR has no smoke or halogen limit in IS 694:2010.
The two types — at a glance.
What each standard actually requires.
| Property | FR | FR-LSH |
|---|---|---|
| Standard | IS 694:2010 (FR designation) | IS 694:2010 (FR-LSH category) |
| Insulation | PVC | PVC (low-smoke, low-halogen compound) |
| Flammability | IS 10810 (Part 53) — burning stops within 60 s of flame removal | Same — IS 10810 (Part 53) |
| Oxygen Index | ≥ 29% — IS 10810 (Part 58) | ≥ 29% — IS 10810 (Part 58) |
| Temperature Index | ≥ 250°C — IS 10810 (Part 64) | ≥ 250°C — IS 10810 (Part 64) |
| Halogen acid gas | No limit in IS 694:2010 | ≤ 20% by weight — IS 694:2010 cl. 10.6, tested per IS 10810 (Part 59) |
| Smoke | No limit in IS 694:2010 | Smoke density rating ≤ 60% — IS 694:2010 cl. 10.8, tested per IS 13360 (Part 6/Sec 9) |
| Conductor temperature | 70°C | 70°C |
| Voltage grade | 1100 V | 1100 V |
| BIS licence | CM/L 8800140116 | CM/L 8800140116 |
Selection guidance.
FR wire is specified for general residential and commercial wiring where the project specification sets no smoke or halogen condition. National Cables suggests FR-LSH for escape routes and for all areas of high-rise residential buildings — in a stairwell fire, lower smoke density protects evacuation. NBC 2016 Part 8/Sec 2 cl. 5.3.7.1 notes that FR-LSH cable is available and may be considered. The project specification governs the cable type.
Specify by product — the National Cables range.
FR Single Core Wire — flame-retardant PVC, IS 694:2010, 0.5–240 mm². FR-LSH Single Core Wire — flame retardant, low smoke and halogen, IS 694:2010. 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-LSH vs LSZH · FR vs LSZH · full three-way comparison.
FR vs FR-LSH — selection questions.
The differences between the two IS 694:2010 categories, and when each is the correct specification.
What is the difference between FR and FR-LSH wire?
Both are PVC wires under IS 694:2010 with the same flame retardance: flammability test per IS 10810 (Part 53), Oxygen Index ≥ 29%, Temperature Index ≥ 250°C.
FR-LSH adds two combustion limits: halogen acid gas ≤ 20% by weight (IS 10810 Part 59) and a smoke density rating ≤ 60% (IS 13360 Part 6/Sec 9). Plain FR has no smoke or halogen limit.
What is the full form of FR and FRLSH?
FR stands for Flame Retardant. FRLSH (FR-LSH) stands for Flame Retardant Low Smoke and Halogen. Both are categories of PVC wire under IS 694:2010.
Can FR wire be used where FR-LSH is specified?
No. FR has no smoke or halogen limit in IS 694:2010, so it does not meet a specification that calls for FR-LSH. The cable supplied must match the category named in the BOQ.
Do FR and FR-LSH have the same temperature and voltage rating?
Yes. Both are rated 70°C continuous conductor temperature at the 1100 V grade of IS 694:2010. The differentiation is fire performance, not thermal or electrical class.
Is FR-LSH halogen-free?
No. FR-LSH is a low-halogen PVC compound — IS 694:2010 permits halogen acid gas up to 20% by weight. Halogen-free cable is HFFR (LSZH) to IS 17048:2018, limited to 0.5%. See FR-LSH vs LSZH.
Specify the correct cable for your project.
Our technical team matches IS 694:2010 and IS 17048:2018 cable types to your project specification.