CCF meaning

CCF (Common Cause Failure) describes, in practice, when two or more items of redundant plant or systems fail together because they are triggered by the same underlying cause, so that the intended redundancy is defeated. The term is not defined in UK or Irish primary legislation or case law; it is an engineering and functional safety concept widely used in regulatory guidance and industry standards (for example IEC 61508/61511 and sector standards), and appears in safety cases, contracts and expert evidence. Regulators (HSE, ONR and the HSA in Ireland) expect duty holders under COMAH/Seveso and other safety regimes to identify, model and reduce CCF risks so far as is reasonably practicable. Key features are: failure of multiple, nominally independent, redundant items; a common initiator (for example shared design defect, software bug, maintenance error, environmental event, common power or control). CCF is sometimes referred to as common mode failure. Typical legal relevance includes: safety case and risk assessment content; SIL/reliability modelling (for example beta‑factor methods); allocation of responsibility in EPC/O&M contracts, warranties and fitness-for-purpose obligations; causation and product liability; and insurance placement and claims (single event/aggregation). Usage and legal significance are broadly consistent across England & Wales, Scotland, Northern Ireland and Ireland.