The fire performance of cables is one area that has come under close scrutiny in recent years. This subject has been hotly debated within the fire and cable communities of late as part of an overhaul on standards affecting fire detection, and 2002 saw the publication of a new British Standard, BS 5839-1: 2002.
The new standard is causing a major rethink on traditional approaches to cable selection in terms of fire performance. 鈥淭he use of fire resisting cables is now recommended for all manual call point and automatic fire detector circuits, as well as all mains power supply circuits,鈥� explains Terry Journeaux, technical marketing manager at cable supplier Pirelli. A key part of the new standard will be the recognition of two different levels of resistance to damage during the course of a fire 鈥� standard or enhanced 鈥� and strict new tests have been developed for the classification of the two grades.
Recommendations for applications of each type are provided in BS 5839. For example, guidance on what to do in networked systems, new rules on cable segregation, restrictions on the use of multicore cable and guidance on the use of cable fixings and accessories are all included.
The moves are a major departure from cable selection of old. 鈥淭he market was divided between soft skin types and micc types,鈥� says Journeaux. 鈥淎pplications standards, for example for a fire alarm, allowed either type according to specifier choice. Now the cables will be classified as either standard or enhanced grade. All existing cable types will need reapproval against BS 5839-1: 2002 and there will be new choices and opportunities for suppliers and users.鈥�
Contractors can be forgiven for being uninformed about the new changes. 鈥淭here is still much confusion in the marketplace concerning the changes in the standards,鈥� admits Journeaux. This is partly due to the fact that when BS 5839 was published in October 2002, the vital test regimes for cable performance were not yet agreed. Now that they are, compliance certifiers such as BASEC are approving manufacturers鈥� cables, who can then take them to the market with confidence (see box, previous page).
Basically, BS 5839-1: 2002 requires three elements for cable compliance. Cables must comply with:
- BS 7629, BS 7846 or BS EN 60702-1 鈥� the constructional standard;
- EN 50200 PH30 (standard) or PH120 (enhanced) 鈥� the new European fire with mechanical shock test;
- BS 8434-1 30 minute (standard) or BS 8434-2 120 minute (enhanced) 鈥� the new UK integrated fire, shock and water tests.
For most suppliers of cable this will mean offering a full range of cables and accessories aimed at both the standard and enhanced markets. Contractors should get a copy of the guidance on the new standard and familiarise themselves with which cable they are looking for in a given application.
BS 5839-1: 2002 fire alarm cable 鈥� can anyone claim certificated compliance?
When BS 5839-1:2002 was published in October 2002, the section on 鈥榗ables, wiring and other interconnections鈥� was heavily revised. The 1988 edition had used BS 6387 as tests to demonstrate the suitability of fire resistant cables. However, BS 5839-1: 2002 stated that 鈥溾�t is now considered that the temperatures, durations and methodology of the tests require revision for cables of fire alarm systems complying with this part of BS 5839鈥�. Two new requirements were therefore given, one for 鈥榮tandard鈥� and one for 鈥榚nhanced鈥� cables. These new requirements are based upon the later BS EN 50200: 2000 Method of test for resistance to fire of unprotected small cables for use in emergency circuits, but with modifications and additional requirements. However, no test procedures were given by which these additional requirements were to be demonstrated. Following publication of BS 5839-1:2002, the standards committee responsible for cable matters was asked to develop the missing test procedures. The committee acted quickly and two drafts for public comment were circulated. These were agreed as suitable for publication in January 2003 subject to the usual standards committee processes and procedural requirements. Now known as BS 8434: Methods of test for assessment of the fire integrity of electric cables, the standard comes in two parts. Part 1: Test for unprotected small cables for use in emergency circuits 鈥� BS EN 50200 with addition of water spray; and Part 2: Test for unprotected small cables for use in emergency circuits 鈥� BS EN 50200 with a 930掳C flame and with water spray. With the formal issue of the standard, independent verification by the British Approvals Service for Cables (BASEC) to an agreed test procedure has taken place. BASEC product certification licences, and therefore BASEC approved fire alarm cables compliant with BS 5839-1:2002, are now available in the marketplace.Quick Fix
Pirelli is hoping to revolutionise the electrical contracting sector with the launch of its FP Firefix cable installation system. Firefix allows Pirelli鈥檚 FP cables to be installed in around one-tenth of the time taken using traditional clips. Pirelli has developed FP Firefix in an exclusive partnership with tool and fixing manufacturer ITW Construction Products. Specially designed cable clips and adaptors have been produced by Pirelli to be used with ITW鈥檚 Spit Pulsa 700E cordless gas nailing tool (left). The system fixes each clip in around ten seconds, is suitable for a variety of substrates and Pirelli offers a ten-year warranty on the system. 鈥淔P Firefix was developed specifically to meet market demand for a fast, cost-effective method of installing cables,鈥� explains Terry Journeaux, technical marketing manager at Pirelli. 鈥淚n a market where the continuing shortage of qualified electricians and rising labour rates are major issues facing electrical contractors, Pirelli is providing a real solution.鈥� Pilot tests carried out by electrical contractors have shown vast improvements in productivity and significant cost savings (see tables 1-4).Source
Electrical and Mechanical Contractor
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