This research set out to determine if the signal from an inexpensive domestic smoke alarm is effective at providing early warning to a fire. An experiment was devised to investigate the effectiveness of the inexpensive domestic smoke alarm signal at alerting occupants to a fire event. The experiment involved constructing an alerting device which could sound an alarm, identical to that of a domestic smoke alarm, at predetermined times between 6pm and 6am. Volunteers from the risk groups of students, Maori and elderly participated for two weeks in the experiment by allowing an alerting device to be installed in their home and responding to three alarm calls. Data from the experiment was used to examine response times to the alarm signal and identify who is particularly at risk to harm from fire. Analysis of the data from the experiment aimed to conclude if inexpensive smoke alarms are effective at alerting occupants to a fire event. The inexpensive domestic smoke alarm signal was found to be 85% reliable at alerting occupants to a fire event, with children aged under ten years and adults whose sleep was influenced by the effects of alcohol identified as not being reliably woken by the alarm.