Abstract: In a first aspect, a hazard detector testing system is provided that comprises: a sensing arrangement configured to detect electromagnetic radiation produced by a hazard detector; and a spacing arrangement configured to engage with the hazard detector and to maintain a predefined distance between the hazard detector and the sensing arrangement when the spacing arrangement is engaged with the hazard detector; wherein the spacing arrangement is in the form of a platform or a ring structure or includes one or more walls and/or a plurality of columns. In a second aspect, a hazard detector testing system may be provided comprising: a sensing arrangement configured to detect electromagnetic radiation produced by a hazard detector; and at least one mask arrangement comprising an opening configured to restrict a field of view of at least one sensor provided on the sensing arrangement.