Wireless Sensor Networks (WSN) are now being used in a range of applications, many of which are critical systems, e.g. monitoring assisted living facilities or for fire detection systems which is the example used in this paper. For critical systems it is important to be able to determine the minimum number of failures that can cause a hazard to occur. This is normally a manual, human intensive, task. This paper presents a novel application of search to both the WSN and safety domains; searching for combinations of failures that can cause a hazard and then reducing these to the minimum possible using a combination of automated search and manual refinement. Due to the size and complexity of the search problem, a parallel search algorithm is designed that runs on available compute resources with the results being processed using R. Copyright © 2013 ACM.