IEC 61810-1:2015 applies to electromechanical elementary relays (non-specified time all-or-nothing relays) for incorporation into low voltage equipment (circuits up to 1 000 V alternate current or 1 500 V direct current). It defines the basic functional and safety requirements and safety-related aspects for applications in all areas of electrical engineering or electronics, such as: general industrial equipment, electrical facilities, electrical machines, electrical appliances for household and similar use, information technology and business equipment, building automation equipment, automation equipment, electrical installation equipment, medical equipment, control equipment, telecommunications, vehicles, transportation (e.g. railways). Compliance with the requirements of this standard is verified by the type tests indicated. In case the application of a relay determines additional requirements exceeding those specified in this standard, the relay should be assessed in line with this application in accordance with the relevant IEC standard(s). This fourth edition cancels and replaces the third edition published in 2008. This edition constitutes a technical revision. This edition includes the following significant technical changes with respect to the previous edition: - two main test procedures were introduced: procedure A, reflecting the procedure known from Edition 3 of this standard and procedure B, reflecting the assessment according to North American requirements; - inclusion of dedicated device application tests especially relevant for applications in the North American Market (see Clause D.1); - introduction of testing under single mounting condition; - clarification of insulation requirements after endurance testing; - inclusion of provisions for basic safety requirements; - update of references.