We have a public building that experienced a fire evacuation recently.....this was initiated by the local duty manager after smoke and "burning smell" noticed in one of the normally unoccupied rooms. Fire Brigade attended and (after 90 minutes investigation) confirmed that no source could be determined, including no evidence of charring etc even though the smoke alarm activated. My question is this.... What other sources could there have been other than these... • Was anything out of the ordinary occurring in the area prior to the alarm initiating? • Electrical problem? • Arson? • Discarded cigarette/match? • Nearby vent pulling in fumes/smoke from outside? • Any contractors working in that area (or nearby)? • Any hot works carried out during the four hour period prior to the incident? • Any drapes/curtains/covers etc have smouldered?

To be honest without knowing exactly what is in the room it’s difficult to say; that said I’m sure you are aware that steam can set smoke detectors off not sure if you have a possible source of steam in this room (someone making a brew?) Aerosols can also trigger smoke detectors (if cleaners/persons used aerosol such as a can of polish or air freshener in a small room then this can trigger a detector). It could also be that the detector itself is at fault (again I’m sure you are aware of the fact that they can develop faults and that they don’t last for ever). If you have a fairly modern alarm system then the company who service your alarm system you should be able to get analogue readings for the detector to see if it is still operating within defined/preset limits. Not an expert on these things but I think the preset limits are the digital numbers an addressable device generates and represent the various conditions that that device can find itself in. These digital numbers can also be different from manufacturer to manufacturer, and from range to range of detectors. HTH smitch

Local duty manager wanting some attention?

Rees When in the Fire Service we would occasionally have smoke detectors activated by small insects - so much so that we had a specific code for such an activation. I think the little blighters were refereed to as Thunder Flies. also the errant and wayward spider was sometimes the culprit

MEden's comment at #7 about insects activating smoke detectors may hve a parallel regarding the passive infra-red (PIR) devices used in security alarms systems. Very occasionally my burglar alarm at home goes off for no evident reason and the only explanation seems to be that a spider or other insect has walked across the front of the PIR device involved (as identified on the alarm system's control panel) and emitted sufficient heat at close range to activate it. Also thanks to tomorton for acquainting us with phantosmia - another new word for some of us to sprinkle in conversations! :-)