Posted By tonyf L2 would seem the sensible option, with escape routes, high risk rooms like plant/lift rooms covered and any room off the escape route covered, you may want to consider wireless to save on disruption to the office areas and decorations as well, some very good systems on the market that are fully complaint with BS5839-1. L2 which primarily covers "life" will be ample in low risk operations such as offices

Posted By Messy Shaw By law, the resp person needs to provide an adequate means of raising the alarm in the event of fire. In certain circumstances - BUT NOT ALWAYS- this may mean automatic detection. BS5839-1 2002+A2:2008 is clear on this. In the case of a low risk building, with the likelihood of a slow developing fire (& low fire loading) and where everyone is awake, alert and familiar with the building, a category M (manual call points & sounders) may suffice. If there is a SIGNIFICANT POSSIBILITY of a fire in an area of the building where it will the escape from the building before the fire has been discovered, then a detection system may be required. So an office, will everyone awake, a 'normal' office fire loading and (where necessary) a protected route, it is very likely that a Cat M system will suffice. Even a single staircase office to 4 floors may be OK. In this example, it is said that the building is large, so likely to have more than one escape route which makes the building even more favourable for a M system. I am not saying in this case detection isn't required - that will be down to a RA taking all specific matters into account - but I am saying, AFD may not be required. So I recommend you read the BS if you can Some care needs to be taken when risk assessing to consider the fire load as some offices have large fire loads than other. Offices attached to fashion houses and those associated to media may have larger than average loadings. Also consider 'inner rooms' with no vision panel where a L5 system may be required with smoke detection in the access room

Posted By philip john I will ask. Thank you