Article by Nilesh Khatri, Regional Technical Manager at BASEC
Fire-rated cables are cables that continue to perform their intended function, i.e. supply of power or control signals, even in the event of a fire, for a minimum time duration as per their fire rating. At the same time, in case of fire, these cables should not emit halogen gases or generate heavy smoke, which is harmful to health. Often known as Fire-Rated Cables, Fire-Resistance Cables, or Fire-Survival Cables; however, the actual cable type or construction depends on the application, fire-duration rating, flame temperature, etc. Fire-rated cables can be used for power distribution, control signals, fire alarms, emergency lighting, and many other applications, as per their criticality.
Depending on the cable construction, we can classify the fire-rated cables into three cable types as follows:
- Single core, Unarmoured, Unsheathed Fire Resistant Cables, 450/750V rated
- Fire Alarm / Emergency Lighting Cables, Unarmoured & Screened, 300/500V rated
- Fire Resistant Power & Control Cables, Armoured, 600/1000V rated
These cables have individual design standards, applications, and criticality. Their fire-resistance test (circuit integrity test) standards, flame temperature, and fire-rating duration also vary by requirement. Some design standards also specify separate fire-rating categories based on fire performance. Below are the cable design standards for the above fire-rated cable types and their fire categories:
- BS 8592
- BS 7629-1 (Fire Categories – Standard 30, Standard 60 and Enhanced 120)
- BS 7846 (Fire Categories – F2, F30, F60 and F120)
Let’s understand these cable design standards, their fire categories and applicable fire tests, with their flame temperature and duration in detail:
BS 8592
| BS 8592 | Single Core Fire Resistant Cables (Unarmoured, Non-sheathed, 450/750V rated cables) |
| Fire Test | Resistance to Fire with Shock as per IEC 60331-3 with 830°C for 120 min |
Cable Construction: Copper Stranded Class 2 Conductor, Fire Barrier Tape like Mica Glass Tape, Halogen-free Cross-linked Insulation Type EI5, 450/750V rated cable.
Cable Range: Single Core – 1.5 to 70 sq.mm
Application: Used in fixed installations (primarily in metal enclosures) in industrial areas, buildings, and similar applications, where maintenance of power supply during a fire is required for a defined period.
Single-core fire-rated cables, certified as per BS 8592, can be requested depending on the application.
BS 7629-1
| BS 7629-1 Category | Fire Alarm Cables / Emergency Lighting Cables (Unarmoured & Screened, 300/500V rated cables) |
| STANDARD 30 | BS EN 50200 PH 30 (30 min of fire survival at 830°C with mechanical impact every 5 min) + BS EN 50200 Annex E (30 min test – first 15 min fire+impact, followed by fire+impact+water spray in last 15 min) |
| STANDARD 60 | BS EN 50200 PH 60 (60 min of fire survival at 830°C with mechanical impact every 5 min) + BS EN 50200 Annex E (30 min test – first 15 min fire+impact, followed by fire+impact+water spray in last 15 min) |
| ENHANCED 120 | BS EN 50200 PH 120 (120 min of fire survival at 830°C with mechanical impact every 5 min) + BS 8434-2 (120 min test at 930°C– first 60 min fire+impact, followed by fire+impact+water spray in last 60 min) |
Cable Construction:
- Conductor: Plain or Tinned Copper Conductor with Class 1 or Class 2, CPC shall be Tinned Copper (full size & same class of main conductor); drain wire for Auxiliary Cables shall be Tinned Copper of 0.5 sq.mm with Class 1 or Class 2
- Insulation: Fire Barrier Tape like Mica Glass Tape (optional), Cross-linked Elastomer EI2 or Halogen-free Cross-linked Insulation Type EI5
- Screen: Metallic or Laminated Metallic Screen(s) with metallic element in contact with CPR or drain wire.
- Sheath: Halogen-free Type LTS3, 300/500V rated cable.
Cable Range:
- 2-core*, 3-core, 4-core – 1.5 to 4 sq.mm with uninsulated full-size CPC conductor
- Auxiliary Cables – 7-core, 12-core, 19-core* – 1.5 to 2.5 sq.mm with uninsulated 0.5 sq.mm drain wire
*2-core has an additional 1.0 sq.mm size, and 19-core has only 1.5 sq.mm size.
Application: Primarily intended for use in emergency lighting, fire detection and fire alarm system circuits.
Product-certified cables, either STANDARD 30, STANDARD 60, or ENHANCED 120 categories of BS 7629-1, can be requested depending on the application.
BS 7846
| BS 7846 Category | Fire-Resistant Power & Control Cables (Armoured, 600/1000V rated cables) |
| F2 | BS 6387 CWZ (Resistance to Fire at 950°C for 3 hours + Resistance to Fire at 650°C for 30 min (15+15) with Water Spray + Resistance to Fire at 950°C for 15 min with Mechanical Shocks – all tests separately) Or Annex I of BS 7846 (WZ test for cable OD>20 mm) |
| F30 | F2 + BS 8491(Resistance to Fire with Direct Mechanical Impact & Water Jet in combination for cable OD>20 mm) (Fire at 830°C for 30 min + mechanical impact in every 10 min. Followed by Fire + Impact + Water Jet (a burst of water for 5 sec) in last 5 min, repeating it every minute) |
| F60 | F2 + BS 8491(Resistance to Fire with Direct Mechanical Impact & Water Jet in combination for cable OD>20 mm) (Fire at 830°C for 60 min + mechanical impact in every 10 min. Followed by Fire + Impact + Water Jet (a burst of water for 5 sec) in last 5 min, repeating it every minute) |
| F120 | F2 + BS 8491 (Resistance to Fire with Direct Mechanical Impact & Water Jet in combination for cable OD>20 mm) (Fire at 830°C for 120 min + mechanical impact in every 10 min. Followed by Fire + Impact + Water Jet (a burst of water for 5 sec) in last 5 min, repeating it every minute) |
Cable Construction:
- Conductor: Copper Stranded Class 2 Conductor
- Insulation: Fire Barrier Tape like Mica Glass Tape, XLPE Insulation Type GP8 or Cross-linked Elastomeric Insulation Type GP6 or Halogen-free Cross-linked Insulation Type EI5
- Bedding: Halogen-free compound
- Armour: Galvanised Steel Wire (SWA)
- Over Sheath: Halogen-free Type LTS1, 600/1000V rated cable.
Cable Range:
- 2-core, 3-core, 4-core – 1.5 to 400 sq.mm
- 5-core – 1.5 to 70 sq.mm
- Auxiliary Cables – 7-core, 12-core, 19-core, 27-core, 37-core – 1.5 to 4 sq.mm
Application: Used in fixed installations in industrial areas, buildings, and similar applications where the power supply must be maintained during a fire for a defined period.
Product-certified cables in the F2, F30, F60, or F120 category of BS 7846 can be requested, depending on the application.
To achieve fire performance, other cable characteristics, such as mechanical, material, or electrical properties, may be compromised, affecting overall cable performance. Therefore, consider overall compliance with the fire-rated cable design standard rather than only fire test performance.
BASEC provides a complete product certification solution for the above fire-rated cables, including material testing, mechanical & electrical tests, chemical, smoke, halogen, and flame propagation tests, as well as fire tests (circuit integrity). Product certification includes factory audits, routine testing, and market surveillance, ensuring peace of mind about the quality of BASEC-marked fire-rated cables.
To view listed and approved fire-rated cable manufacturers, please check the BASEC website
Original announcement: BASEC
Image: Courtesy of BASEC
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