CASS Accredited Certification

​In addition to using the CASS methodology for creating evidence of compliance (i.e., for in-house purposes, self-declaration, etc) it has also been used for many years by Accredited Certification Bodies to gain an extension to their scope to issue certificates of conformity to IEC 61508 (or related standards).

CASS methodology

This approach enables industry to have the added assurance of using the services of a certification body working in accordance with the relevant certification standards (i.e., ISO/IEC  17065, previously ISO/IEC Guide 65) under the auspices of a national accreditation body (e.g. UKAS). Accreditation involves the some assessment of the competence and impartiality of an organisation and the compliance of their work to nationally and internationally recognised standards or schemes, such as IEC 61508.

IEC 61508 and related functional safety standards do not require certification, they require demonstrable compliance for the functional safety requirements within the standards. Certification is an accepted method for proactively demonstrating compliance rather than having to rely on demonstrating compliance reactively for each project / sale. There is no globally accepted functional safety certification scheme so the quality of a functional safety certification can vary. The 61508 Association recommends the checking of certificates and associated safety manuals carefully (by competent staff). Like it or not certification has a key role within functional safety.

For the Certification Body, the CASS methodology is effectively an “off the shelf” set of technical procedures that can be integrated into their existing procedural framework, saving significant effort and cost.

Safety requirements specification

For the assessee, there are benefits of using a certification service based on the CASS methodology:

  • As the process is open, the assessee can prepare accordingly and avoid or reduce any major surprises.
  • Any work done previously by the assessee to document evidence of compliance (e.g., for a self-declaration) can be fed into the certification process.

Generally, the main advantages of accredited certification are:

  • increased level of rigour and assurance via a check of the checkers (see;
  • impartiality of assessment;
  • high level of independence (e.g., where higher SILs are involved);
  • certificates can help support marketing of the product or service;
  • demonstrates due diligence from an plant owner/operator.

Note: the level of rigor is defined by the national accreditation body (e.g., UKAS) and the certification body not the CASS methodology.

The relevant forms for accredited certification bodies are on the Downloads page.

Self-assessment of your functional safety is a good starting point for many organisations that are new to functional safety. IEC 61508 and some related standards require functional safety audits and independent functional safety assessments. Compliance with functional safety can, however, be a challenging task and as an organisation progesses on its functional safety journey getting an independent and impartial assessment from a 3rd party offers significant benefits. When you do look towards 3rd parties expect to invest especially in management, admin, and tools (when software is a consideration).  The impartiality requirements for Accreditation limits the advice and guidance a certification body can provide, so competent consultants can also be useful in combination with certification bodies.

Important Note: Certification bodies that use the CASS methodology and have received national accreditation (to ISO/IEC 17065) for the relevant functional safety standard may use the CASS Mark (available on request via contacting The CASS Scheme Association via The 61508 Association).