A neglected way of talking about risk is to focus on one of its correlates, 'safety'. This study examines how fire-safety knowledge is put into action. We are concerned with how knowledge of household fire 'risk factors' may, or may not, gain a concrete existence in the interactions between firefighters and householders. Using a 'translation' model loosely derived from Actor-Network-Theory, we show the complexity of the social interactions that constitute safety in action. The aim is not to critique the 'risk factors' approach and its epidemiological underpinnings; nevertheless, the implication is that proponents of the 'risk factors' approach need to understand the interactions where risk and safety are socially embedded, for this is where they gain their life.