The LWF Blog

Fire Safety Engineering for Design – Fire Detection & Alarm Systems – Part 149

September 11, 2023 10:57 am

LWF’s Fire Safety Engineering blog series is written for Architects, building designers and others in the construction industry to highlight and promote discussion on all topics around fire engineering. In part 148, LWF looked at the necessary recommendations for fire alarm system designed for buildings outside British Standards. In part 149, we discuss manual call points, often referred to as break-glass units.

Manual call points are commonly installed in non-domestic buildings to allow personnel to raise the alarm in the event of a fire. They are designed so that a frangible element may be broken easily.

A break glass unit permits an individual who has discovered a fire on the premises to raise the alarm, alerting other building occupants and notifying the control equipment of the area the alarm was raised in. For this reason, the siting of manual call points is important. They should enable the person operating them to:

  1. Raise the alarm as soon as possible after discovering the fire and in the general area of the fire
  2. Use the manual call point on their way to a place of safety, e.g. the storey exit (stairway) or exit to open air

Guidance for the siting of manual call points should be as per BS 5839-1 which includes the following:

  • Manual call points should be sited on all storey exits (to stairs) and all exits into the open air
  • They should be located so that they are within 45 metres of any position within the premises, unless there are factors which increase risk, such as building occupants with limited mobility or a high risk of rapid fire spread in which case the distance may need to be lower
  • For the majority of premises, manual call points should be positioned 1.4 metres above the floor, easily-accessible, well-illuminated and free of obstructions
  • All manual call points within a building should operate in the same manner, unless there is a justifiable reason why they should be different

When considering how the manual call points should work within an overall fire detection and alarm system, there are some points regarding zoning to be considered.

If they are located on the landing of an enclosed staircase (except final exit call point) they should be included in the zone serving adjacent accommodation on that level.

While it is possible for manual and automatic devices to be installed on the same system, it is advisable to install the manual call points on separate zones for speed of identification at the control and indicating equipment.

In part 150 of LWF’s series on fire engineering, we will begin to discuss the different types of fire detection devices. In the meantime, if you have any questions about this blog, or wish to discuss your own project with one of our fire engineers, please contact us.

Lawrence Webster Forrest has been working with their clients since 1986 to produce innovative and exciting building projects. If you would like further information on how LWF and fire strategies could assist you, please contact the LWF office on 0800 410 1130.

While care has been taken to ensure that information contained in LWF’s publications is true and correct at the time of publication, changes in circumstances after the time of publication may impact on the accuracy of this information.

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