Does “Performance Level” Really Replace “Category” For Machine Safety In The U.S.?

Over the next ten years picture a safety circuit with six safety certified components and four are certified to Performance Level (PLx) and the other two are certified to Cat.x! Is the outcome clear?
By J.B. Titus February 28, 2011

Over the next ten years picture a safety circuit with six safety certified components and four are certified to Performance Level (PLx) and the other two are certified to Cat.x! Is the outcome clear?

True, the European Machinery Directive has ruled that EN 954-1; 1996 will be fully replaced in December, 2011 by EN/ISO 13849-1; 2008. Therefore, the Category system is being replaced by the Performance Level system of hazard determination and mitigation. Ah, but you say – Categories are still covered in EN/ISO 13849-1; 2008 as a part of the PL analysis so are Categories really a thing of the past here in the U.S.?

First, the U.S. never adopted EN 954-1; 1996 as a normative/required compliance standard. In fact, ANSI’s Accredited Standards Committee has ruled that European standards will not be normatively referenced as a required compliance standard in the U.S.  Therefore, whether it’s an active standard or not in Europe is superfluous to the question. In reality, only pieces of EN 954-1; 1996 were written into U.S. standards, such as Categories. With that said, Categories are now a part of U.S. standards, are they not?

Secondly, I’m told by many Europeans that EN/ISO 13849-1; 2008 (as a part of the Machinery Directive) is primarily focused at the machinery manufacturer for designing and manufacturing machines. Yet in the U.S., OSHA is primarily focused at the end users in industry and our consensus standards reinforce OSHA but are also applied to the OEM and engineering firms building and retrofitting machines for end users. Do we have a focus discrepancy between ourselves and our European colleagues?

Thirdly, global safety component and automation manufacturers/suppliers are already transitioning their product safety certifications from SIL per IEC 61508 and Cat per EN 954 to SIL per IEC 61508 and PL per EN/ISO 13849-1. In my opinion, this transition in certifications will aggravate the situation in the U.S. because there isn’t a mandate to move from Cat to PL. So,  over the next ten years picture a safety circuit with six safety certified components and four are certified to Performance Level (PLx) and the other two are certified to Cat.x!

Has the hazard been fully mitigated to the intended and acceptable level?

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Related articles:

Trouble Implementing ISO 13849-1; 2006 per the European Machinery Directive

EN 954-1: 1996 – Five Years Of Cessation

EN ISO 13849-1; 2006 – Are We Ready? 

It’s Official – EN 954-1:1996 Is Extended By The EU

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