Industry Intelligence

Is the newest edition of IEC 60601-1 a perfect compliance document or does it need an update? Professional readers of the third edition of IEC 60601-1 agree that the standard's promotion of innovation and new technology is a major step in the right direction. It represents a paradigm shift away from fixed requirements towards requirements based on scientific evidence provided by the manufacturer. This makes the medical standard a pioneer in its field. We will see other product standards follow this philosophy (the future version of IEC 61010 is a good example).

As with all new technology there are teething troubles, and the third edition of IEC 60601 is no exception. One of the major concerns involves the new transformer requirements.

Transformers are the dominant components used to ensure insulation compliance in the majority of electrical devices. The second edition of IEC 60601-1 incorporated all of the construction and testing requirements; the third edition splits testing and construction requirements between IEC 60601 and IEC 61558.

At first glance, one might approve of this approach; after all, IEC 61558 is a dedicated standard for transformers. But a thorough analysis of the two standards and their discrepancies reveals a number of issues that may lead to uncertainty and potentially unsafe constructions. A close inspection of the insulation requirements outlined in IEC 61558 shows that the standard was not designed to meet the extended insulation requirements of IEC 60601.

IEC 61558 was designed for coping with the testing and construction requirements for transformers and was intended for use in combination with a Particular Requirement standard in the IEC 61558 series. As a horizontal standard, IEC 61558 was also meant to support a variety of product standards. However, the question is whether the special needs outlined in IEC 60601 can be satisfied by IEC 61558. Because risk management is an integral part of IEC 60601, this philosophy should be passed down to components standards like IEC 61558 in order to allow innovation in this vital component. This is especially important considering that IEC 60601-1 covers more than just mains transformers. IEC 61558 is missing the risk management approach and does not consider the newest technology using risk management.

The solution to the problem should be seen from a short- and long-term perspective, and it should satisfy both existing and future technologies as part of the IEC 60601 philosophy. Three tools are available in the current IEC system for Conformity testing and Certification of Electrotechnical Equipment and Components (IECEE): amending the standard; providing clarification by means of decisions reached by the Committee of Testing Laboratories (CTL); and adding IEC 61558-2-xx, intended for transformers used in medical device applications. Each solution has its own time frame and depth, and a combination of solutions should be considered.

As it stands, the intent of IEC 60601 is likely to be compromised if the immediate wording outlined in IEC 60601 and IEC 61558 is followed blindly. The standards leave the user in an inconclusive situation; inexperienced users could be misled into making decisions with serious consequences. However, following the old second edition approach ensures a safe construction in line with the third edition, and only minor modifications are required to ensure compliance with third edition requirements.

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