As an engineer working in the UK, I’ve seen first-hand how functional safety standards have shifted from being specialist knowledge to an essential part of everyday engineering practice. Whether you’re working in the automotive field, process industries, or machinery design, understanding the right standards is fundamental to safety, compliance, and professional credibility.
In this article, I’ll walk through the top functional safety standards every UK engineer should know and explain why investing in formal functional safety training is one of the smartest decisions you can make for your career.
Functional safety standards define requirements that ensure electrical, electronic, and programmable systems reduce risk to an acceptable level. These standards specify safety integrity levels (SIL 1–4), lifecycle processes, risk assessment methods, and validation procedures. Examples include IEC 61508 the basic standard for all industries, IEC 61511 for the process industry and ISO 26262 for automotive systems.
Their purpose is to define requirements so that when faults occur, as they inevitably will, systems respond correctly and move to a safe state rather than causing harm.
Functional safety focuses on:
In the UK, functional safety is widely recognised as part of good engineering practice, with regulators such as the HSE referencing standards like BS EN 61508 as a benchmark.
The functional safety standard IEC 61508 defines requirements for designing, implementing, and maintaining safety-related electrical, electronic, and programmable electronic (E/E/PE) systems. IEC 61508 establishes Safety Integrity Levels (SIL 1–4) and lifecycle processes that reduce the probability of dangerous failures in industrial systems such as control systems, machinery, and process plants.
IEC 61508 is the generic, cross-industry‑ functional safety standard that underpins most other standards.
SILs (from SIL 1 to SIL 4) define how dependable a safety function must be, based on the level of risk it is intended to reduce. Higher risk demands higher integrity.
Misunderstanding SIL requirements can lead to:
This is one reason why engineers need to stay current as new functional safety standards and interpretations continue to develop across industries.
The functional safety standard ISO 26262 defines requirements for ensuring functional safety in automotive electrical and electronic systems. ISO 26262 establishes Automotive Safety Integrity Levels (ASIL A–D) and a safety lifecycle that manages hazards caused by system malfunctions in road vehicles, including software, hardware, and system development processes.
Learn more about our ISO 26262 functional safety training courses including ISO 26262 Automotive Functional Safety Training and Certification for Engineers (Level 1).
The IEC 61511 standard defines functional safety requirements for Safety Instrumented Systems (SIS) used in the process industry. IEC 61511 establishes a safety lifecycle that manages hazards in facilities such as oil, gas, non-nuclear power generation and chemical plants. The standard requires risk analysis, Safety Integrity Level (SIL 1–3) assignment, and lifecycle management to reduce dangerous process failures.
In the UK, IEC 61511 is recognised by the HSE as a benchmark standard for managing functional safety in process industries. For engineers working with process plants, understanding IEC 61511 is essential which is why we offer IEC 61511 Process Functional Safety Training and Certification for Engineers (Level 1).
Another standard that UK engineers frequently encounter is ISO 13849, which applies to the safety of machinery control systems.
ISO 13849 is an international safety standard that defines how to design and validate safety-related control systems in machinery. ISO 13849 evaluates machine risk and assigns a required Performance Level (PL a–e). Engineers apply ISO 13849 to design safety functions that reduce risks associated with machine hazards through reliable hardware and software architecture.
ISO 13849 focuses on:
It is commonly used in machinery design and manufacturing, especially where simpler or well-defined safety architectures are involved. While it takes a different approach from IEC 61508, the underlying functional safety principles remain the same.
If you want to improve your knowledge of ISO 13849, book our Functional Safety Engineer for ISO 13849 & IEC 62061 Training Course.
IEC 62061 is an international machinery safety standard that defines functional safety requirements for safety-related control systems on machinery. IEC 62061 applies the Safety Integrity Level (SIL 1–3) framework to evaluate risk and design safety-related control functions that reduce risks associated with machine hazards through validated system architecture.
IEC 62061 is particularly relevant when:
Understanding when to apply ISO 13849 versus IEC 62061 is a common challenge and one that formal training, such as our Functional Safety Engineer for ISO 13849 & IEC 62061 Training Course, helps to clarify.
Owning a copy of the standards doesn’t mean understanding them.
Functional safety standards are detailed, technical, and easy to misinterpret. UK guidance explicitly highlights the importance of competence, not just documented processes, in functional safety roles.
Training helps engineers:
If you work with safety-critical systems, investing in professional training is one of the highest‑-value decisions you can make.
Our functional safety training courses support engineers working across automotive, process industries, and machinery by translating complex standards into practical, real-world‑ knowledge.
Functional safety standards, including IEC 61508, ISO 26262, IEC 61511, ISO 13849, and IEC 62061, are becoming more important as systems grow to be more automated and interconnected.
Engineers who invest in understanding functional safety standards will be better positioned to lead safer, more successful projects. And in safety-critical engineering, confidence makes all the difference.
The main functional safety standard is IEC 61508, an international standard that defines requirements for designing, implementing, and maintaining safety-related electrical, electronic, and programmable electronic systems. IEC 61508 establishes Safety Integrity Levels (SIL 1–4) to measure risk reduction and guides industries such as automotive, energy, and industrial automation.
The main difference between IEC 61508 and IEC 61511 is scope. IEC 61508 defines functional safety requirements for all electrical, electronic, and programmable electronic (E/E/PE) safety systems across industries. IEC 61511 applies those principles specifically to Safety Instrumented Systems (SIS) used in the process industry, such as oil, gas, and chemical plants.
The main difference between IEC 62061 and IEC 61508 is scope and application. IEC 61508 defines functional safety requirements for all electrical, electronic, and programmable systems across industries. IEC 62061 applies those principles specifically to industrial machinery control systems and defines Safety Integrity Levels (SIL) for machine safety functions.
The current version of IEC 61508 is IEC 61508:2010. IEC published this second edition in April 2010. The standard contains seven parts that define functional safety requirements for electrical, electronic, and programmable electronic safety-related systems. IEC began developing a third edition in 2021, but IEC 61508:2010 remains the active published version.
The main difference between ISO 13849 and IEC 61511 is industry scope and safety methodology. ISO 13849 defines machine safety requirements using Performance Levels (PL a–e) for industrial machinery control systems. IEC 61511 defines functional safety requirements for Safety Instrumented Systems (SIS) in the process industry using Safety Integrity Levels (SIL 1–3).
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