LOW SMOKE ZERO HALOGEN (LSZH) CABLES HAVING STANDARD CIRCUIT INTEGRITY WHEN EXPOSED TO FIRE - BASED ON BS7629
Tratos Firesafe cables are manufactured in Italy and the United Kingdom in accordance with British Standards BS5389, BS6387 and BS EN 50200 and can be BASEC-approved and can be LPCB (Loss Prevention Certification Board) certified, when circuit integrity is required in case of fire.
Protected circuits are required where it is critical that an electrical circuit continues to operate during a fire. This should include the use of sufficiently robust cables, careful selection of cable routes, and/or by the provision of physical protection in areas where cables may be susceptible to damage.
Tratos TW950S standard (PH 30) cable are constructed with silicone rubber insulated cores, which are overlaid with a electrostatic aluminium foil screen in contact a tinned copper drain wire and LSZH sheathed. The cables are manufactured and supplied with a red sheath for fire alarm and building evacuation systems and a white sheath for other safety critical systems such as emergency lighting, public address and help points.
Screens are often used in instrumentation cables to prevent or reduce possible interference in cables that can be caused by the following reasons: • Cross-talk between adjacent pairs or triples; • Interference induced by an external source such as electrical equipments, machinery, power line. The most popular screen is: ALUMINIUM/POLYESTER TAPE with a tinned copper drain wire or earth conductor.
These cables are typically clipped and installed on to walls, ceilings and in certain external areas of buildings; they have an operating temperature range of -10oC to +90oC.
British Standards (BS) and Euro Norm (EN) for these types of fire resistance set out to test the integrity provided by a cable during fire in particular, circuit continuity at rated voltage. Each of these British Standards & Euro Norm is a specification for the actual fire test. They detail the design and dimensions of test rigs and how many cable samples are used, how they are prepared and how the burners are calibrated. They list the methods of cable attachment, how circuit continuity is measured, the test voltages and the burner gas and air mixture.
The standards call for fire resistant cables to ‘standard’ performance or ‘enhanced’ performance. The essential difference between the ‘standard’ and ‘enhanced’ requirement is survival time under the test conditions as set out in BS EN 50200. Cables which survive for a minimum of 30 minutes are classed as ‘standard’ while cables that can survive for 120 minutes are classed as ‘enhanced’. BS 5839-1: Fire detection and fire alarm systems for buildings are the code of practice for design, installation, commissioning and maintenance of systems in non domestic premises.”
BS 5839-1 is a ‘code of practice’ which provides considerable information In terms of cable it describes the requirements for circuit integrity during fire and advises upon the use of ‘standard’ or ‘enhanced’ fire resistant cable for different parts of the building. It refers to a number of details, for example the preferred sheath colour of the cable, to the metallic fixing methods and lists other British Standards to meet the requirements for critical circuits in fire detection and fire alarm systems. This British Standard is the starting point for designers and installers of fire alarm systems and forms part of the maintenance programme for the life of the building.
- BS 6387; Categories C, W & Z
- BS EN 50200; PH30 (30 minutes annex E)
- BS EN 60332-1 and BS EN 60332-3; Flame propagation
- BS EN 60754 Acid gas emission
- BS EN 61034; Smoke emission
ApplicationFiresafe TW950S is designed for installations where a fire situation may pose a hazard and the maintenance of circuit integrity is a requirement . Applications include airports, railway & sub surface metro stations, schools, hospitals, retail stores, cinemas, hotels, theatres, data centres and similar applications where “standard” grade cable is specified for use in the applicable code of practice.
- Conductor: solid or stranded plain annealed copper class 1 or class 2 conductor
- Insulation: extruded silicone rubber
- Electrostatic Screen: laminated aluminium foil in direct contact with a tinned annealed copper drain wire
- Sheath: thermoplastic LSZH sheathing compound
- Standard Colours: red or white
- Identification of Core
- 2 core + bare earth: Brown, Blue
- 3 core + bare earth: Brown, Black, Grey
- 4 core + bare earth: Brown, Blue, Black, Grey
- Marking: TW950 +TRATOS+ BASEC BS7629-1 BS6387 CWZ BS5839-1 PH30 2X1,5+E LOT/YEAR -METRE MARKING - “CE”
- Voltage Rating 450/750V
- Operating temperature range of -10oC to +90oC.
- Maximum short circuit conductor temperature 250 °C, maximum duration of the fault current 5 s.
- The tension applied to a cable should not exceed the values of tensile stress per conductor given below. This is subject to a total maximum tensile force of 1000 N.
- 50 N/mm2 during installation;
- 15 N/mm2 for static tensile stress.
- Minimum bending radius: ≤8 mm 4D; >8 mm ≤12 mm 5D; >12 mm 6D