Until 2018, the limited firefighting means in the SPS complex largely exposed it to the consequences of self-ignition or accidental fire. In 2015 the SPS Fire Safety project was launched with the objective of improving life safety and property protection by deploying a whole set of automatic actions to protect SPS in case of fire outbreak. If nothing was done, an unmanaged fire could be a threat to lives of those working underground and could mean losing a vast majority of the SPS machine and its equipment. In 2020, CERN has completed the consolidation of its SPS fire safety systems. Among these, a water based sprinkler system, following principles of standard industrial design but customized and tailor-made for SPS and its irradiated areas, is ready to operate. The system must take into account limitations related to the presence of fragile accelerator equipment, radioactive zones, integration constraints and comply with European norms, in particular EN12845. This paper presents the risk assessment, our experience from the planning and installation phase while discussing the custom-chosen and radiation tested equipment to end up with the lessons learned and outlook for the future