The motto of the worldwide Scout Movement, “Be Prepared”, is a good mantra for all aspects of life and, in business, is undeniably the key to success. In engineering and design, part of being prepared means keeping abreast of changing regulations and the requirements of international standards.
The IEC 60601-1 medical standard is a case in point. This standard governs the basic safety and essential performance of medical electrical equipment, and has particular implications for the design of power supplies. Through various revisions over the past 40 years, the standard has detailed the requirements that have to be met in order for medical equipment to be sold in territories around the world that mandate compliance.
The next revision of the standard, generally referred to as the 4th edition, is due to come into effect in the US, Canada and Europe from January 2019. This post aims to highlight the changes this edition introduces and offers medical equipment designers a way of being prepared that also eases the challenge of ensuring compliance.
Why is IEC 60601-1 changing and what are the latest requirements?
Over time the IEC 60601-1 standard has reflected the changing situations within which medical equipment is used. The original premise of the standard is mirrored by its full title “IEC 60601-1 - Medical electrical equipment - Part 1: General requirements for basic safety and essential performance”. These requirements were spelled out in a series of “collateral” and “particular” standards in terms of how they should apply to specific types of product.
The standard evolved by first considering the safety of equipment operating within the vicinity of a patient, establishing the “means of protection” needed to ensure safety according to the degree of contact between patient and equipment. This approach was refined in the 3rd edition of the standard, to distinguish between the level of protection provided for a patient and the equipment’s operator. Since then, edition 3.1 was published in 2012 to update some of the standard’s earlier definitions that had become ambiguous due to the introduction of new technologies.
Essentially, the 3rd/3.1 editions define safety in terms of the isolation, creepage and insulation requirements needed to achieve “means of operator protection” (MOOP) and “means of patient protection” (MOPP) classes of use – these are particularly pertinent to power supplies, as discussed in the following section. What the 3rd edition also sought to establish was an understanding of risk. Thus, a risk management process (based on ISO 14971) was adopted, requiring the equipment designer and manufacturer to work closely with the compliance testing laboratory to achieve certification.
The latest evolution of the standard once more takes account of where medical equipment will be used, especially in light of today’s proliferation of wireless communication devices. Specifically, the new collateral standard, “IEC 60601-1-2 Electromagnetic disturbances – Requirements and tests”, published in 2014, recognizes that medical electrical equipment is no longer confined to use in hospital-type environments and therefore might have to contend with issues of RF interference from modern sources such as mobile phones and Wi-Fi signals.
Hence, alongside traditional professional healthcare facilities, this collateral standard defines two further “intended use environments”: home healthcare and “Special” environments. Home-use clearly embraces non-specialist use of medical devices in locations where medical staff are not present, while “Special” covers situations where high levels of electromagnetic disturbance may be present, e.g. in a radio-therapy treatment room.
Consequently, the 4th edition, which embraces this new collateral standard, raises the bar with more stringent EMC immunity tests, as is evident from the table below. The latest edition further develops the risk management philosophy introduced by the 3rd edition:
What does the IEC 60601-1 standard have to do with power supplies?
Apart from small medical devices like pacemakers or cochlear implants, which operate from batteries or perhaps use harvested energy, all other medical electrical equipment will require a power supply that becomes an integral part of its design when considering the requirements of the IEC 60601-1 3rd edition for means of protection and the 4th edition for EMC immunity, as detailed in the following tables.
Meeting these requirements for the equipment as a whole and understanding the contribution that the power supply may be making can be challenging for a system designer, who is unlikely to be a power design expert. While it does not remove the need for overall compliance testing and certification, a solution that eases this challenge would be to adopt a pre-certified power supply that fully meets the current and upcoming IEC 60601-1 regulations. In view of the impending deadline for complying with the IEC 60601-1-2 collateral standard, this would also allow equipment manufacturers to get to market quicker with compliant products.
Where does IEC 60601-1 apply and how long do I have?
Compliance with edition 3.1 is mandatory now in the US, Canada and Brazil and will be required from January 2018 in Europe and South Korea. Japan currently mandates the 3rd edition while for domestic use within China and Taiwan, compliance to the 2nd edition is all that is required. However, products made for export in countries like China or Taiwan, will need to meet the prevailing standard in the territory they are destined for.
Compliance with the 4th edition has been harmonized between the US, Canada and Europe and will apply from January 2019 with other countries undoubtedly to follow suit. The global timeline for compliance with the various editions of IEC 60601-1, including the 4th edition EMC standards is fully detailed here.
Buying ready-qualified power supplies is one way to be prepared for the introduction of new standards. CUI offers a range of embedded and external medical power supplies from 6 watts to 550 watts that are fully compliant with the 4th edition requirements of IEC 60601-1 and are available now to keep your products in compliance.
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