Standards: Connect to international machine-control safety

By Control Engineering Staff December 28, 2006

If you aren’t already aware that big things are afoot in the machine-control safety arena, you will be soon. International standards-setting bodies are wrapping up the process of harmonizing North American (specifically U.S.) standards regarding machine-safety systems with more advanced European standards.

As part of the normal International Electrotechnical Committee (IEC) maintenance cycle, the existing standard (IEC 61508) is currently being revised. Amendments are based on comments received from national committees.

Two international maintenance teams are responsible. Maintenance Team 12 (MT12) covers IEC 61508-3 and Maintenance Team 13 (MT13) handles IEC 61508-1, IEC 61508-2, IEC 61508-4 and IEC 61508-5. The other two parts, IEC 61508-6 and IEC 61508-7, contain informative text in support of IEC 61508-2 and IEC 61508-3, and responsibility is divided accordingly between MT13 and MT12.

Work of the two maintenance teams are coordinated under one project leader. Parts 1 to 4 of IEC 61508 are being revised simultaneously and will be subject to the various consultative stages at the same time. Parts 5 to 7, which provide guidance on parts 1 to 4, will be included from the stage of committee draft with vote. Stages 1 to 5 have been completed. This month (December 2006), drafts of revisions are due from international committees with vote of parts 1 to 7 and will be issued to national committees for comment and voting. That is, the draft revisions generated by the international committees will go to various national committees—including the U.S.—for comment and voting.

While is one milestone in a process that typically takes many years, it is important for those interested in building equipment that conforms to standards. It is the first time the nearly-final revisions are available together for public review. Final drafts of parts 1 to 7 is scheduled to be issued to national committees for voting in January 2008, with the final revision of parts 1 to 7 due to be fully published by May 2008.

Control engineers who must conform to these standards in their work are well advised to learn about this standard-making activity now. Considering the time it takes to develop products in the machine-control industry, and the technical complexity of the standards, competitors who have better understanding of the standard and its ramifications may gain competitive advantage.

The IEC website provides an excellent resource for learning about IEC 61508, the changes being made to it, and the revision process in general. An informational page in question-and-answer format provides information about the standard’s sections, what they cover, how they relate to other existing standards, how control engineers should use the standards, and how to get involved in the process.

To reach the IEC 61508 information page, visit

For more information about machine safety, visit the Control Engineering website at and type ‘machine safety’ into the search bar on any page and look for more articles in upcoming online and print publications from Control Engineering .

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— C.G. Masi , Control Engineering senior editor