The Safety Standard Landscape after IEC 60950
2020/11/02
Many engineers have grown up with the IEC 60950 safety standard as a backdrop to their careers, either as designers of IT power supplies and systems or as users of IT equipment. The standard dates back to 1986 in its first incarnation as IEC 950, entitled ‘Safety of information technology equipment including electrical business equipment’. It was adopted as a CENELEC standard EN 60950 in 1988 and by UL as UL standard 1950 in 1989, replacing UL 478. UL later aligned its numbering with CENELEC in 2000 with UL 60950, and approval agencies worldwide have referenced the standard ever since.
IEC 60950 and its national versions became the default safety standards for many types of electronic and electrical equipment whenever there wasn’t a specific product standard, although it was originally intended for IT and office equipment. For this reason, it also became the accepted international safety standard for AC/DC power supplies and DC/DC converters.
The landscape of electronic equipment has changed, with distinctions between IT and other electronic equipment becoming less defined. For example, there is a separate IEC standard for audio/video equipment, IEC 60065, and one for household appliances, IEC 60335-1, but is a ‘smart’ TV with Wi-Fi and an integrated web browser IT equipment, audio/video equipment, or a household appliance?
The answer to this uncertainty is the new standard UL/IEC/EN 62368-1 (although IEC 62368 was first released in 2010), which will supersede both IEC/EN 60065 and IEC/EN 60950-1 on 20 December 2020. It is titled ‘Audio/video, information and communication technology equipment’ and will serve as a catch-all for many products as they become increasingly internet-connected, whether used domestically, industrially, or in business environments. Only specialist equipment such as industrial motor drives, medical devices, rail systems, and professional test equipment, which previously referred to IEC 60950, will still retain alternative standards to UL/IEC/EN 62368 for their specific applications.
Not all IEC member countries have adopted IEC 62368, and dual certification with IEC 60950 and IEC 62368 may be necessary in some locations. Some applications can use alternate harmonized standards to justify CE marking, so market confusion remains. The German organization ZVEI has released a guidebook to assist in selecting appropriate safety standards for power supplies, available in English and German (RECOM contributed to compiling this guide along with other leading German power supply manufacturers).
To some extent, the same concept applies to EMC standards. Since IEC 60950 is primarily an IT standard, the matching EN 55022/55024 (CISPR 22/24) pair sufficed for almost all applications. With the withdrawal of IEC 60950, other EMC standards are now relevant. Adding to the complexity, EN 55022 has been superseded by EN 55032 (limits remain the same), and EN 55024 has been superseded by EN 55035 (test methodology changed, limits largely unchanged). For household applications, a different set of EMC standards applies: EN 55014-1 and EN 55014-2.
Several technical working groups and HAS consultants are developing a new EN 62368-1 (based on IEC 62368-1 3rd edition), but it will not appear in the OJ until late 2021 or early 2022. This creates a gap in EU certifications: the old EN 60950-1 is being withdrawn, the official replacements (EN 62368-1:2014 and EN 62368-1:2014+A11:2017) are based on IEC 62368-1 2nd edition and will be withdrawn on 6 Jan. 2023, while the most up-to-date EN 62368-1 (IEC 62368-1 3rd edition) is not yet listed.
The international standard IEC 62368-1 3rd edition has been published, and 3rd edition certificates and CB reports are available from test houses. The IEC 62368-1 2nd edition will remain valid only until 20 Dec. 2020, the same date as the withdrawal of IEC 60950. More countries still have national differences for IEC 62368-1 2nd edition than for the 3rd edition, and existing CB certificates and test reports covering IEC 62368-1 2nd edition remain valid after 20 Dec. 2020. As a general rule, CB certificates do not have an expiry date. Additionally, EN 62368-1:2014 and EN 62368-1:2014+A11:2017 (both based on IEC 62368-1 2nd edition) and IEC 62368-1 2nd edition include clause 4.1.1, allowing components compliant with IEC 60950-1 to be used in end applications even after 20 Dec. 2020.
UL has not set a withdrawal date for UL 62368-1 2nd edition, but all new RECOM products will be tested and certified to UL 62368-1 3rd edition. Like EN 62368-1, UL 62368-1 2nd edition allows the use of UL 60950-1 components in end applications (“grandfathering” scheme).
Several certification scenarios exist for RECOM products:
The table below shows the current standards landscape.
The landscape of electronic equipment has changed, with distinctions between IT and other electronic equipment becoming less defined. For example, there is a separate IEC standard for audio/video equipment, IEC 60065, and one for household appliances, IEC 60335-1, but is a ‘smart’ TV with Wi-Fi and an integrated web browser IT equipment, audio/video equipment, or a household appliance?
The answer to this uncertainty is the new standard UL/IEC/EN 62368-1 (although IEC 62368 was first released in 2010), which will supersede both IEC/EN 60065 and IEC/EN 60950-1 on 20 December 2020. It is titled ‘Audio/video, information and communication technology equipment’ and will serve as a catch-all for many products as they become increasingly internet-connected, whether used domestically, industrially, or in business environments. Only specialist equipment such as industrial motor drives, medical devices, rail systems, and professional test equipment, which previously referred to IEC 60950, will still retain alternative standards to UL/IEC/EN 62368 for their specific applications.
Hazard-Based Safety Engineering in IEC 62368
The old IEC 60950 standard is prescriptive, defining design rules for insulation materials, safety spacings, and AC mains over-voltage levels, regardless of practical use. IEC 62368 reflects the trend toward hazard-based rather than prescriptive safety standards. This requires designers to take a proactive approach using Hazard-Based Safety Engineering (HBSE) principles, obliging them to consider and mitigate potential hazards from the use of the equipment in end applications. For this reason, IEC 62368 is not only an alternative to IEC 60950 but also a replacement, as IEC 60950 will be withdrawn and no longer accepted as a basis for CE marking after 20/12/2020.Not all IEC member countries have adopted IEC 62368, and dual certification with IEC 60950 and IEC 62368 may be necessary in some locations. Some applications can use alternate harmonized standards to justify CE marking, so market confusion remains. The German organization ZVEI has released a guidebook to assist in selecting appropriate safety standards for power supplies, available in English and German (RECOM contributed to compiling this guide along with other leading German power supply manufacturers).
To some extent, the same concept applies to EMC standards. Since IEC 60950 is primarily an IT standard, the matching EN 55022/55024 (CISPR 22/24) pair sufficed for almost all applications. With the withdrawal of IEC 60950, other EMC standards are now relevant. Adding to the complexity, EN 55022 has been superseded by EN 55032 (limits remain the same), and EN 55024 has been superseded by EN 55035 (test methodology changed, limits largely unchanged). For household applications, a different set of EMC standards applies: EN 55014-1 and EN 55014-2.
Certification and Compliance for AC/DC Power Supplies and DC/DC Converters
Further complexity arises because UL, IEEE, and CENELEC regularly update standards to keep them fit for purpose. Although UL 62368-1, IEC 62368-1, and EN 62368-1 3rd edition standards have been published, the EU Official Journal currently lists only EN 62368-1:2014 (based on IEC 62368-1 second edition) as harmonized for CE marking under the Low Voltage Directive. EN 62368-1:2014+A11:2017 (also based on IEC 62368-1 2nd edition) is expected to be listed by 20 Dec. 2020.Several technical working groups and HAS consultants are developing a new EN 62368-1 (based on IEC 62368-1 3rd edition), but it will not appear in the OJ until late 2021 or early 2022. This creates a gap in EU certifications: the old EN 60950-1 is being withdrawn, the official replacements (EN 62368-1:2014 and EN 62368-1:2014+A11:2017) are based on IEC 62368-1 2nd edition and will be withdrawn on 6 Jan. 2023, while the most up-to-date EN 62368-1 (IEC 62368-1 3rd edition) is not yet listed.
The international standard IEC 62368-1 3rd edition has been published, and 3rd edition certificates and CB reports are available from test houses. The IEC 62368-1 2nd edition will remain valid only until 20 Dec. 2020, the same date as the withdrawal of IEC 60950. More countries still have national differences for IEC 62368-1 2nd edition than for the 3rd edition, and existing CB certificates and test reports covering IEC 62368-1 2nd edition remain valid after 20 Dec. 2020. As a general rule, CB certificates do not have an expiry date. Additionally, EN 62368-1:2014 and EN 62368-1:2014+A11:2017 (both based on IEC 62368-1 2nd edition) and IEC 62368-1 2nd edition include clause 4.1.1, allowing components compliant with IEC 60950-1 to be used in end applications even after 20 Dec. 2020.
UL has not set a withdrawal date for UL 62368-1 2nd edition, but all new RECOM products will be tested and certified to UL 62368-1 3rd edition. Like EN 62368-1, UL 62368-1 2nd edition allows the use of UL 60950-1 components in end applications (“grandfathering” scheme).
Several certification scenarios exist for RECOM products:
- Finished UL certifications can either keep existing UL 60950-1 or get update to either UL 62368-1 2nd or 3rd edition. New RECOM products of course will only be certified to UL 62368-1 3rd edition.
- Finished UL certifications can retain existing UL 60950-1 or be updated to UL 62368-1 2nd or 3rd edition. New RECOM products will be certified only to UL 62368-1 3rd edition.
- Finished CB certifications with IEC 60950-1 and IEC 62368-1 2nd edition remain valid without mandatory updates. New RECOM products will be certified to IEC 62368-1 3rd edition (assuming most countries update national differences), otherwise IEC 62368-1 2nd edition may be used where required.
- Existing RECOM products without CE mark (DC/DC converters <75VDC) with IEC 60950-1 and EN 60950-1 can be updated to IEC 62368-1 and EN 62368-1 or retain IEC 60950-1 for end applications considering clause 4.1.1. New DC/DC converters will be certified to EN 62368-1:2014+A11:2017 or EN IEC 62368-1:2020+A11:2020 3rd edition.
- Existing RECOM products with CE mark (DC/DC converters >75VDC and AC/DC converters) with IEC 60950-1 and EN 60950-1 can be updated to EN 62368-1:2014+A11:2017 or retain IEC 60950-1 for end applications, referencing a RECOM rationale document, updated risk assessment, and CE declaration. New CE products will be certified to EN 62368-1:2014+A11:2017 (assumed added to harmonized standards list by 20 Dec. 2020).
The table below shows the current standards landscape.
| Application | Safety Standard | Name | EMC Standard | Comment |
|---|---|---|---|---|
| General Purpose | IEC/EN/UL 62368-1 | I.T.E and Audio/Visual Equipment | EN 55032/EN 55024 (later EN 55035) | Suitable for most applications |
| Household/Building Automation |
IEC/EN/UL 60335-1 IEC/EN/ 61558-2-16 |
Household Equipment Power supplies up to 1100W |
EN 55014-1/EN 55014-2 | |
| DIN Rail Power Supplies | IEC/EN/UL 61010-2-201 | Control Equipment power supplies | EN 55032/EN 55024 (later EN 55035) | UL 508 discontinued for new products |
| Test and Measurement | IEC/EN/UL 61010-1 | Measurement, Control & Lab Equipment | EN 55032/EN 55024 (later EN 55035) | |
| Industrial/UPS Power | IEC/EN 60204-7 IEC/EN 62477-1 |
Low Voltage power supplies: DC output | EN 55032/EN 55024 (later EN 55035) | Would be a good alternative to 62368, but no UL equivalent |
| Medical | IEC/EN 60601-1 ANSI/AAMI 60601-1 |
Medical Electrical Equipment (3rd Edition) | EN 60601-1-2 (4th Edition) | UL don't have their own standard, but use ANSI/AMII |
| Lighting | UL 8750 IEC/EN 61347-1 IEC/EN 61347-2-13 |
LED Equipment General Safety: Lamp control gear Requirements: LED control gear |
EN 610000-3-2 EN 61547 EN 61000-4-x |
Certificates for UL 8750 can be issued by other test houses than UL |
| Railway Rolling Stock | EN 50155:2017 | Electronic equipment for rolling stock | EN 50121-3-2:2016 | Most 50155 certificates have not been updated to the new version |
| Asia/USA | IEC/UL 60950-1 | I.T.E | EN 55032/EN 55024 (later EN 55035) | Most of Asia has not updated their certifications yet, so will still accept IEC 60950. UL will accept existing UL 60950-1 certifications after 2020, but not issue new certificates |