EU Directives 98/37/EC (machinery directive) and 94/9/EC (ATEX 100A) have to be applied by manufacturers of equipment and protective systems intended for use in potentially explosive atmospheres. These Directives include Essential Safety Requirements and place an onus on manufacturers to carry out a risk assessment for the intended use of their equipment. In order to help manufacturers in this task, the European Standards organization, CEN, TC 305 has mandated its WG 4 (terminology and methodology) to write a standard on the risk assessment of equipment and protective systems intended for use in potentially explosive atmospheres. The RASE project was set up as a prenormative research work to define the requirements for developing such a standard as specified in the dedicated call of the European Commission's Standards Measurement and Testing programme concerned with subjects relating to the standardization activities of CEN - Explosive atmospheres - risk assessment of unit operations and equipment. The project (December 1997-May 2000) was co-ordinated by INBUREX with the participation of FSA Germany, INERIS France, HSE England, NIRO Denmark and CMR Norway. Since March 2000, WG 4 (TC 305) is actively involved in preparing the final draft of this standard. This paper describes the objectives and the results obtained to date in RASE project and in WG4. An outline is given of the contents of the standard being developed for the risk assessment of equipment and protection systems intended for use in potentially explosive atmospheres.