A Fire Alarm System Design Guide

Fire Alarm system Design Guide

The sounder device should give a minimum sound level of 65dB(A) or 5dB(A) above any background noise lasting more than 30 seconds. It shall operate at 500Hz to 1000Hz. All systems should have a minimum of 2 sounder circuits

Fire Alarm system Design Guide
A person searching a zone for a fire should not have to travel more than 60m to identify the source of a fire. A person should not have to travel more than 45m to reach a manual call point
Fire Alarm system Design Guide
For areas where people are sleeping, sounder devices should produce a minimum of 75dB(A) at the bed-head with all doors shut. Decibel loss occurs through doors: -20dB(A) through a normal door, -30dB(A) through a fire door.
Fire Alarm system Design Guide
For ceilings that feature an apex: as long as the height of the apex from the rest of the ceiling is less than 150mm for Heat detectors or less than 600mm for smoke detectors, then these can be treated the same as flat ceilings. For higher apexes, a device should be installed at the highest point. The distance to adjacent devices can be increased by 1% per 1 degree of the angle of the roof.
Fire Alarm system Design Guide
Manual Call points should be positioned 1.4m (/-200mm) from floor level (DDA requirements should be taken into account). Any non-mechanically protected cable medium should have additional protection up to 2m from floor level.
Fire Alarm system Design Guide
Heat detector covers 50m2. Should not exceed 3.5m from any given point. General spacing guidance: 3.5m from a wall, 7.5m between detectors
Fire Alarm System design guide
Smoke detector covers 100m2. Should not exceed 7.5m from any point. General spacing guidance: 5m from a wall, 10m between detectors.
Fire Alarm System design guide
Do not site detectors less than 1m from air inlets or air conditioning units.
Fire Alarm System design guide
Detectors should not be mounted within 500mm of any obstruction. If the top of solid partition is less than 300mm from the ceiling, it should be treated as a wall. Similarly, ceiling obstructions such as beams should be treated as walls if they are deeper than 10% of the ceiling height.
Fire Alarm System design guide
Vertical shafts like lifts and stairways should have a detector mounted within 1.5m of any opening. Enclosed stairways should have a detector on each main landing.
Fire Alarm System design guide
Voids less than 800mm in height need not have independent coverage, unless fire or smoke is able to spread from one area to another through the void or risk assessment shows an AFP (Automatic Fire Protection) to be necessary. Obstructions such as beams will lessen coverage. Beams more than 10% of room height regard as a wall.
Fire Alarm System design guide
Never mount detectors closer than twice the depth of luminaire.
Fire Alarm System design guide
The sensing element of a Heat detector (thermistor) should not be less than 25mm below the ceiling and not greater than 150mm below the ceiling.
Fire Alarm System design guide
The sensing element of a Smoke detector should be below 25mm from the ceiling, but not more than 600mm.

Please note: All call points must be of the same type to ensure that testing can be completed.

Approved Document M requires all communal toilets and bathroom/shower areas to be fitted with flashing visual indicators.

PROPERTY PROTECTION 
P1/M
Manual call points plus rooms and areas excluding small lobbies and cupboards plus sounder / strobes outside and Redcare.
P2/M  Manual call points plus areas listed on paperwork. When P2/M there is always a detector sited near the fire panel.
LIFE PROTECTION
L1/M  As per P1/M except sounders / strobes outside.
L2/M  All escape routes and rooms that lead onto escape route plus specified areas must be listed. Redcare recommended.
FL3/M  All escape routes and rooms that open onto it. Redcare recommended.
L4/M  Escape routes plus staircases only.
MANUAL ONLY 
TYPE M Only call points no detectors

These guidelines reflect the main requirements of BS5839. Channel Safety Systems are pleased to offer a Free Design Service* on Fire Alarm — Emergency Lighting — Assistance Systems.

Channel Safety Systems offers a complete Design, Supply & Commissioning service:-

  • Fire Alarm. To BS.5839. Part 1 2013
  • Emergency Lighting. To BS. 5266. Part 1 2011
  • Nurse Call Systems
  • Disabled Refuge Systems

Channel Safety Systems provide a dedicated design, supply and commissioning service for Emergency Lighting, Fire Alarm and Assistance.

With over 35 years’ experience working within these sectors, Channel’s knowledge base is extensive and is an invaluable resource for our customers. As Industry standards are ever-changing, we make it our mission to keep abreast of regulatory and legal changes that aff ect our clients. As our Territory Managers and Service Engineers are based across the UK, we off er a fast and effi cient service for design, site surveys, project management and all commissioning and maintenance services requirements. All our external team members are fully qualified to ‘sign off ’ designs and Channel maintains all the relevant insurance policies which means the legal onus is on us, not the contractor.

* The design service is free on the basis of receipt of order on contract award

This guide should be read in conjunction with current standards.

DDA — Sounder Strobes in all toilets and communal areas — refer to part M.

Building Regulations 2000 Part M should be read in conjunction with BS.5839. Part 1 2002.

Please note: All systems that include call points must be suffixed with M, ie P2/M, P1/M etc.

Any areas which require detection and have a void over 800mm (height) require detection within this void.

Approved Document M states that in Hotels, Motels, student accommodation or other buildings offering sleeping accommodation for a significant number of people, both audible and visual indication must be given in the bedrooms, communal toilets and bathrooms/shower rooms.