History of CASS

​CASS was formed soon after publication of the first edition of IEC 61508 in 1998. Sponsored as a UK government-funded initiative, it was intended to provide an industry-wide approach and interpretation to IEC 61508 assessment and certification.

The scheme had the involvement and “buy-in” from many safety-related system stakeholders: regulators, plant owner/operators, engineering companies, systems integrators, instrumentation suppliers, certification and accreditation bodies. One of the original objectives of CASS was that the assessment criteria, scope, guidance and approach should be open to all and the scheme documents have always been freely available in the public domain.

For traceability to its origins, further details about CASS are contained in the ‘CASS Guide to Functional Safety’ which, although is now out of date, may be of interest to some.

The scheme also provided competence criteria to ensure that assessors were technically competent in the areas covered by the assessments they were performing. For accredited certification, assessor competence is determined by the certification body, but the ‘CASS Assessor Guide’ may still be useful guidance when considering assessor criteria, alongside other industry guidance on competence.


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