BS 7846:2000 Electric cables - 600/1000 V armoured fire-resistant cables having thermosetting insulation and low emission of smoke and corrosive gases when affected by fire
This British Standard specifies the requirements for construction and performance, and describes methods of test, for armoured fire-resistant cables with thermosetting insulation and of rated voltage 600/1 000 V and low emission of smoke and corrosive gases when affected by fire.
The circuit integrity performance under fire conditions is assessed on the basis of various tests which either separately measure resistance to fire, resistance to fire with water, and resistance to fire with mechanical shock (Categories Fl and F2), or in combination measure resistance to fire with mechanical shock and water (Category F3).
Cables specified in this standard are intended for use in fixed installations in industrial areas, buildings and similar applications, where maintenance of power supply during a fire is required for a defined period of time.
For the purposes of this standard, cables are designated by category according to their special performance characteristics. The following categories are included:
Category Fl — resistance to fire alone when tested in accordance with 17.4.2;
Category F2 — resistance to fire, resistance to fire with water, resistance to fire with mechanical shock, assessed separately when tested in accordance with 17.4.3;
Category F3 — resistance to fire with mechanical shock and water assessed in combination when tested in accordance with 17.4.4.
NOTE 1 Attention is drawn to the fact that the ability of a given cable to meet a particular category in this standard refers only to the test condition stated, and the level of performance achieved in a particular installation may be influenced by actual installation conditions.
Cables covered by this standard have limited evolution of smoke and corrosive gases when assessed under the fire conditions as specified in BS EN 50268 and BS EN 50267-2-1.
In this standard, the level of corrosive (and acid) gases is determined by measurement of hydrochloric acid (HCI) in accordance with BS EN 50267-2-1.
NOTE 2 This is an indirect assessment method, and reference should be made to IEC 60695-5-2:1994, 5.1.5 for additional guidance.
The insulation and other components are suitable to permit operation of the cables at a maximum sustained conductor temperature of 90 ℃ and for a maximum short circuit conductor temperature of 250℃.
NOTE 3 Limitation on the temperature of the cables may be imposed in situations where they may be touched.
NOTE 4 Due to the relatively high conductor temperature, there is a risk of drying out the surrounding soil causing an increase in thermal resistivity which in turn would lead to the cable temperature rising to a higher value than anticipated. For cable laid directly in the ground, a suitable de-rating factor should be applied or a lower maximum sustained conductor operating temperature should be assumed to take into account the possible effects of soil drying out.
NOTE 5 In installations which include cable joints and terminations, the performance of these accessories should be taken into account in deciding the maximum operating temperature of the cable.
The cables specified in the standard are all wire armoured and oversheathed and are as follows:
a) two-, three-, four- and five-core stranded copper conductor;
b) multicore auxiliary stranded copper conductor.
Annex A gives recommendations for the selection and operation of cables while recommendations for the installation of cables are given in Annex B. Annex C lists the information that should be given with an enquiry or order.
BS 7846:2000 history
2015BS 7846:2015 Electric cables. Thermosetting insulated, armoured, fire-resistant cables of rated voltage 600/1 000 V for fixed installations, having low emission of smoke and corrosive gases when affected by fire. Specification
2009BS 7846:2009 Electric cables - Thermosetting insulated, armoured, fire-resistant cables of rated voltage 600/1000 V, having low emission of smoke and corrosive gases when affected by fire - Specification
2000BS 7846:2000 Electric cables - 600/1000 V armoured fire-resistant cables having thermosetting insulation and low emission of smoke and corrosive gases when affected by fire