The cable Can Survive under Fire Fire resistant cable is cable which will continue to operate normally in the presence of prolonged fire for a specifi...
The cable Can Survive under Fire
Fire resistant cable is cable which will continue to operate normally in the presence of prolonged fire for a specified time under defined conditions.
Flame retardant cable. The flame retardant cable is mainly featured in low liability of fire or that second combustion is only limited to a certain range, meets the IEC60332 combustion testing requirements, and is applicable to the places with flame retardant requirement.
Different wiring applications call for different levels of fire performance. The fire performance characteristics or a cable are tested against a variety of standards including measurement of flame propagation, smoke and gas emissions amongst others.
For fire performance cables, under fire conditions, there are two main classifications:
Fire Survival and Fire Resistant.
- Fire Survival demonstrates exceptional capabilities for prolonged functionality for circuit and data integrity in extreme fire conditions. The fire survival cable systems are constructed of inorganic materials which do not burn, emit smoke or gas and which survive the harshest fire conditions. These systems are designed for life-critical and fire management systems where life safety is dependant on cable/system functionality for prolonged periods.
- Fire Resistant demonstrates resistance to fire and maintain circuit integrity for an approved period of time. They are constructed from organic materials and burn when subjected to fire conditions.
Mineral insulated cables are widely accepted as the only true Fire Survival cable technology.
For fire alarm systems, there are two clear classification as part of the British Standard BS5839-1:2002; Standard and Enhanced grades.
Under test conditions:
- Standard Grade cables need to remain functional for 30 minutes when subjected to 830°C.
- Enhanced Grade cables need to remain functional for 120 minutes when subjected to 930°C.
The single cables sample is also subject to a water source and indirect mechanical shock as part of the test regime.
The Pyro MI portfolio of products meet and exceed these test regimes.
Essential power applications, (non fire alarm) cable diameters above & below 20mm overall dimater, a new standard BS7346-6:2005 Components for smoke and heat control systems Part 6 Specification for Cable systems was published in March 2005. This more stringent standard ensures increased performance levels for cables by incorporating an integrated test method of:
- Flame/Heat direct acting on the cable
- Mechanical impact direct to the cable
- Water jet direct to the cable (to simulate fire fighting and/or water leakage from the building.)
Pyro MI cables are compliant with the test requirements of BS7346-6: 2005.
The new edition of BS 5839-1:2002 (Fire detection and alarm systems for buildings – Part 1: Code of practice for system design, installation, commissioning and maintenance) describes two levels of fire performance for fire rated cabling for fire alarm systems.
These performance levels have now been published within a British Standard. BS 8434: 2003 Parts 1 and 2 (Methods of test for the assessment of the fire integrity of electric cables). Pyro MI easily complies with and exceeds all the requirements for Enhanced Grade and Standard Grade described within these standards.
Fire Performance BS 6387: 1994 Performance Requirements for Cables Required to Maintain Circuit Integrity under Fire Conditions. This standard details the following tests to categorise cables according to their fire withstand capabilities.
Resistance to Fire 950°C for 3 hours – Category C
The cable is tested by exposure to gas burner flames while passing a current at its rated voltage. Four survival categories are defined in the table below.
Resistance to Fire with Water Spray 650°C – Category W
A new sample of cable is exposed to flames at 650°C for 15 minutes whilst passing a current at the rated voltage and then the spray is turned on to give exposure to both fire and water for a further 15 minutes. A single survival category is defined in the table below.
Resistance to Fire with Mechanical Shock 950°C Category Z
A fresh sample of cable is mounted on a backing panel in an S-bend and is exposed to flames whilst the backing panel is struck with a solid steel bar the same diameter as the cable under test every 30 seconds for 15 minutes whilst the cable has been exposed to temperatures as defined in the table below.