Technical Annexe 13.12

Fire Alarm Systems

This Technical Annexe contains benchmarks in respect of fire detection and alarms, against which the existing level of provision can be compared.

Where these benchmarks are not achieved and the results of the risk assessment indicate risk reduction measures are required, consideration should be given to implementing improvements.

1. For enclosed shopping centres see also Technical Annexe 13.15.

System Type

2. Where an electrical fire alarm system is necessary, a fire detection and warning system designed, installed and maintained in accordance with the guidance in BS 5839: Part 1 for a Category M system is likely to be appropriate for many offices, shops and similar premises. A category M system is a system designed to give a warning of fire and is operated by manual call points only.

3. Where automatic detection of fire is necessary for life safety the system will be designated as a category L system, within which there are subdivisions from L1 to L5.

• L5 is a system designed to achieve a specific fire safety objective
• L4 is a system which provides warning of smoke within escape routes
• L3 is a system designed to give a warning before escape routes are impassable
• L2 is a system designed to give warning before escape routes are impassable but with enhanced coverage in specified areas
• L1 is a system installed throughout all areas of the building

Power Supply

4. The fire alarm system should have a power supply for the system derived from a mains supply and a back up power supply.

Call Points

5. Manual call points are normally positioned at every exit and storey exit, not just those designated as fire exits. They should be conspicuous, fitted at a height of about 1.4m (or less for premises with a significant number of wheelchair users), and not in an area likely to be obstructed. They should normally be positioned so that no one should have to travel more than 45m to reach the nearest call point.

6. If a manual call point is placed in a stock area where there is continual movement of stock, the call point may be accidentally damaged. A simple, hinged guard around the call point may be fitted. Where there is high potential for malicious operation, a hinged cover, with or without a tamper alarm, may be fitted as a deterrent.

Sounders

7. An appropriate sound level for sounders will vary with the nature of the premises and staffing arrangements.

Voice Alarm Systems

8. Where a voice alarm system is installed then it should comply with the guidance in BS5839: Part 8. In considering the areas of the premises to be provided with a voice alarm system, the desirability or otherwise of providing occupants with information regarding the fire and factors such as background noise levels need to be taken into account. The wording of the message on the voice alarm system should be clear, unambiguous and precise. A coded staff alert message may be desirable in some circumstances.