LOW SMOKE ZERO HALOGEN (LSZH) CABLES HAVING ENHANCED CIRCUIT INTEGRITY WHEN EXPOSED TO FIRE
Tratos optical fibre corrugated steel armoured (CSTA) cables are manufactured in Italy and are IMQ-approved 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.
The cables are manufactured and supplied with for safety and building evacuation critical systems.
The fibre optic cables cable are constructed with multi or single mode fibres, loose tube jelly filled, with a mica glass fire barrier tape which are overlaid with a aramid strengthening yarns, inner sheathed, CSTA armorured and LSZH sheathed.
Cable armouring is used if mechanical protection is required. The following installation points have to be considered; Required tensile load, expected pressure on cable during service, rodent protrection, protection against accidental damage, minimum required bending radius. CSTA armpouring provides a good mechanical protection and tensile strength.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.
- CEI IEC 60331-11 Ed. 1999 equivalent CEI 20-36/1-1 Ed. 1 2003-03:
Test for electric cables under re conditions Part 11 apparatus fire alone at flame temperatures of at least 750°C.
- CEI IEC 60331-25 Ed. 1999 equivalent CEI 20-36/2-5 Ed. 1 2002-03:
Test for electrical cables under fire conditions – circuits integrity part 25 procedures and requirements optical fibre cables.
ApplicationFiresafe optical fibre cables have been designed for use in areas where optical fibre cables are required to operate in the event of a fire and are used in railway and highways tunnels, mass transit underground metro systems and public buildings.
- Fibre: 62 .5/125 multimode fibres
- Tube: jelly filled loose tube
- Tape: Fire Resistant Wrapping
- Inner Sheath: polyethylene
- Strength Member: aramidic
- Tape: corrugated steel
- Outer Sheath: LSZH
- Standard Colour: violet (more colors are available upon request)