IS 1646:2020 is the Indian Standard (BIS) for fire safety of buildings - general: electrical installations - code of practice. This code outlines fire safety requirements for electrical installations in buildings. It provides guidelines on the safe installation of substations, switchgear, wiring, cables, and emergency power systems to prevent electrical fires and restrict their spread.
Specifies requirements for fire safety concerning electrical installations in buildings, applicable to HVAC electrical components.
Key fire resistance ratings, emergency lighting levels, cable performance criteria, and critical clearances for electrical installations in buildings.
| Reference | Value | Clause |
|---|---|---|
| Fire Resistance (Oil Transformer Room)— Applies to walls, floor, ceiling, and doors of the enclosure. | ≥ 4 h | Cl. 8.2.1.2 |
| Fire Resistance (Dry Transformer Room)— Applies to walls, floor, ceiling, and doors of the enclosure. | ≥ 2 h | Cl. 8.2.2 |
| Fire Resistance (Switchgear/Panel Room)— Doors shall have a fire resistance rating of not less than 1 h. | ≥ 2 h | Cl. 8.1.2 |
| Fire Resistance (Generator Room)— For enclosures housing prime mover and generator set. | ≥ 2 h | Cl. 8.3.1 |
| Fire Resistance (Battery Room)— To be located on an external wall of the building. | ≥ 2 h | Cl. 8.4.1 |
| Fire Resistance (Fire Pump Room)— Cables for fire pumps shall be of the fire survival type. | ≥ 2 h | Cl. 8.5.1 |
| Fire Stop Rating (Penetrations)— Fire stop rating must not be less than the fire rating of the penetrated element. | ≥ Rating of element | Cl. 9.1 |
| Emergency Lighting Duration— Minimum duration for battery-supplied emergency lighting. | ≥ 3 h | Cl. 8.7.2 |
| Emergency Lighting (Escape Route Axis)— Minimum illumination at floor level along the centre line. | ≥ 1 lux | Cl. 8.7.3 |
| Emergency Lighting (Open Area > 60m²)— Excludes a 0.5 m border around the area. | ≥ 0.5 lux | Cl. 8.7.3 |
| RCD Sensitivity (Fire Protection)— For protection against fire caused by persistent earth fault currents. | ≤ 300 mA | Cl. 7.2.1 |
| Generator Day Tank Max Capacity— If >500 L, must be in a separate room with 4h fire resistance. | 500 litres | Cl. 8.3.2 |
| Oil Transformer Room Sill Height— To contain oil spillage within the enclosure. | ≥ 150 mm | Cl. 8.2.1.2 c) |
| Battery Room H₂ Concentration Limit— Ventilation must prevent hydrogen build-up to this explosive limit. | < 1 % by volume | Cl. 8.4.3 |
| Cable Smoke Density (Cat. W)— Tested as per IEC 61034-2 for low smoke properties. | Light Transmittance > 60% | Cl. 6.2.2.1 (Annex A, Table A.1) |
| Cable Acidity (Cat. Z)— Tested as per IEC 60754-2 for halogen-free properties. | pH > 4.3 | Cl. 6.2.2.1 (Annex A, Table A.1) |
| Cable Halogen Acid Gas (Cat. Z)— Tested as per IEC 60754-1 for halogen-free properties. | < 0.5 % | Cl. 6.2.2.1 (Annex A, Table A.1) |
| Clearance (Equip. > 500 W to Combustible) | ≥ 100 mm | Cl. 6.1.3.1 (Table 1) |
| Clearance (Equip. 100-500 W to Combustible) | ≥ 60 mm | Cl. 6.1.3.1 (Table 1) |
| Rooftop PV Firefighting Access— Clearance from roof edges and between arrays for firefighter access. | ≥ 1 m from edges | Annex E-6 |
BIM-relevant code. See the BIM Hub for ISO 19650, IFC, and LOD/LOIN frameworks used alongside it.
| Parameter | IS Value | International | Source |
|---|---|---|---|
| RCD Sensitivity for Fire Protection | Recommends RCD with sensitivity of ≤ 300 mA for protection against fire (Annex B). | Requires protection by RCDs with a rated residual current ≤ 300 mA in locations with specific fire risks (BD2, BD3 conditions). | IEC 60364-4-42:2010 |
| Mandate for AFDDs | Recommended as a measure for protection but not mandated for specific circuits/locations. | Required on AC final circuits for socket-outlets ≤ 32A in specific high-risk residential buildings. | BS 7671:2018+A2:2022 |
| Fire Resistance of Safety Circuit Cables | Cables for fire safety installations shall have a fire resistance of not less than 2 hours (Clause 7.2.2). | Requires 'appropriate fire resistance' based on the specific application and national building regulations, without specifying a universal duration in the wiring code itself. | BS 7671:2018+A2:2022 |
| Cable Supports in Escape Routes | Wiring shall not impede evacuation; emphasizes use of fire-resistant cables. | Cabling systems shall be supported so they are not liable to 'premature collapse' in a fire (interpreted as requiring non-combustible/metallic supports). | BS 7671:2018+A2:2022 |
| Selection of Fire Performance Cables | Specifies use of Fire Retardant Low Smoke (FRLS) or Low Smoke Zero Halogen (LSZH) cables for public areas and escape routes. | Selection based on risk assessment for the whole installation and compliance with other building regulations, often leading to LSZH use. | BS 7671:2018+A2:2022 |
| Minimum Separation from Heat Sources | Wiring shall be run at a sufficient distance from heat sources. Provides specific guidance on clearances from non-electrical services. | A wiring system shall not be installed in the vicinity of a heat source so that it is adversely affected. Requires segregation from non-electrical services that may cause a risk. | IEC 60364-5-52:2009 |