IEC 60601-1-2:2014 applies to the basic safety and essential performance of Medical Equipment (ME) equipment and ME systems in the presence of electromagnetic disturbances and to electromagnetic disturbances emitted by me equipment and me systems. This collateral standard to IEC 60601-1 specifies general requirements and tests for basic safety and essential performance with regard to electromagnetic disturbances and for electromagnetic emissions of ME equipment and ME systems. They are in addition to the requirements of the general standard IEC 60601-1 and serve as the basis for particular standards. This fourth edition cancels and replaces the third edition of IEC 60601-1-2, and constitutes a technical revision. The most significant changes with respect to the previous edition include the following modifications: - specification of immunity test levels according to the environments of intended use, categorized according to locations that are harmonized with IEC 60601-1-11: the professional healthcare facility environment, the home healthcare environment and special environments; - specification of tests and test levels to improve the safety of medical electrical equipment and medical electrical systems when portable RF communications equipment is used closer to the medical electrical equipment than was recommended based on the immunity test levels that were specified in the third edition; - specification of immunity tests and immunity test levels according to the ports of the medical electrical equipment or medical electrical system; - specification of immunity test levels based on the reasonably foreseeable maximum level of electromagnetic disturbances in the environments of intended use, resulting in some immunity test levels that are higher than in the previous edition; and - better harmonization with the risk concepts of basic safety and essential performance, including deletion of the defined term "life-supporting". This new edition includes the following main additions: - guidance for determination of immunity test levels for special environments; - guidance for adjustment of immunity test levels when special considerations of mitigations or intended use are applicable; - guidance on risk management for basic safety and essential performance with regard to electromagnetic disturbances; and - guidance on identification of immunity pass/fail criteria.