Interpreting Safety Standards to Identify Functional Safety Requirements

15 Jun 2026

It’s not about Finding a Single Rule, but Recognizing the Indicators that Signal when Functional Safety Applies

When developing products for residential or commercial use, industrial machinery, automation systems, automotive applications, or any technology that could expose people or the environment to risks, a critical question inevitably arises:

“Does this product require functional safety?”

Although the question seems straightforward, the answer is rarely obvious. Safety standards are complex, and they seldom explicitly state that functional safety is required. Instead, its expectations are embedded within scope statements, definitions, terminology, and risk‑based criteria that must carefully be interpreted.

The following guidance provides a clear framework for determining when functional safety applies and how to make that determination with confidence. Keep in mind, each product is unique and functional safety requirements between different products and standards are not always the same.

Begin With the Standards Table of Contents & Scope – Your Primary Indicator

Every safety standard includes a scope section that defines:

• The types of products and applications covered
• Installation expectations and applicable codes
• Explicit exclusions (e.g. what the standard does not cover)
• The hazards, performance characteristics, or sometimes even safety functions within its purview

The standards Table of Contents can also provide insight. Key sections that may indicate functional safety relevance include:

• Safety System Analysis or Risk Assessment requirements
• Electronic Protective circuits and controls clauses
• Annexes or Supplements dedicated to “functional safety” or “safety-related electronic circuits”
• Electromagnetic immunity (EMC) test requirements

Identifying References to “Safety Functions” or “Safety‑Related Systems”

Functional safety ensures that safety functions perform correctly when required. If a safety standard references the following elements, it is an indication you may have functional safety considerations:

• Requirements to conduct a safety analysis consisting of hazard identification, risk analysis and risk evaluation
• Identification of safety functions and associated risk reduction measures
• Assignment or targeting safety ratings such as SIL, PL, ASIL, or Class
• Validation or Verification activities for safety‑related control systems

Common terminology and safety level indicators may include:

Key terms:	Reference to safety levels:
Safety function or Functional Safety Risk Assessment and Hazard Analysis Protective Circuits or Controls Limiting Control Safety Circuits Protective Electronic Circuit (PEC) Safety Critical Function (SCF) Failure Mode and Effects Analysis (FMEA) Mean Time to Dangerous Failure (MTTFd) Software or Firmware Fault tolerance Diagnostic coverage Safe state	SIL (Safety Integrity Level) – IEC 61508 PL (Performance Level) – ISO/EN 13849-1 ASIL (Automotive Safety Integrity Level) – ISO 26262 Class (Class B, C) – IEC/UL 60730-1, CSA C22.2 No. 0.8 and IEC/UL 60335 (Annex R) Class (Class 1, 2) – UL 1998 Searching for the above standard numbers may also be a helpful method to locate Functional Safety requirements within a product standard

These terms are not included in the standard unless functional safety is an integral part of the required approach.

Determination of whether the Standard Requires a Risk Assessment or Risk Reduction

If a standard requires the following, functional safety is typically one of the prescribed risk‑reduction strategies:

• Conducting Hazard and Risk Assessment (HARA)
• Identifying appropriate risk‑reduction measures
• Determining the risk level and corresponding target safety level – such as PL, SIL, or Class – based on the severity of potential injury, likelihood of occurrence, and probability of avoidance identified in the HARA (hazard and risk assessment)

For example:

• ISO 12100 requires risk reduction but does not prescribe functional safety directly.
• When risk reduction depends on electronic controls or control systems, functional safety standards such the following are typically the main standards referenced:
  1. ISO 13849‑1 covers safety‑related parts of control systems for machinery safety.
  2. IEC 61508 applies to E/E/PE (electrical/electronic/programmable electronic) safety‑related systems.
  3. ISO 26262 applies to automotive E/E systems whose malfunction could create hazardous situations.
  4. IEC/UL/CSA 60730, UL 1998, UL 991, CSA C22.2 No. 0.8 apply to automatic electrical controls whose malfunctioning behavior could lead to hazards.

Rule of thumb:

If the required risk‑reduction measures depend on an electronic control or control system –particularly for hazards such as fire, electric shock, personal injury, or specialized hazards like explosion, then functional safety is applicable.

Determination of whether Programmable or Automatic Controls are Used

Functional safety becomes essential when safety‑related tasks rely on:

• Programmable Logic Controllers (PLCs)
• Embedded systems such as microcontrollers running software or firmware routines
• Sensors, actuators, and other electronic control hardware elements

Standards often signal this through references to:

• E/E/PE systems (electrical/electronic/programmable electronic)
• Programmable safety systems
• Evaluation of probability of dangerous failure (PFH_d, MTTF_d, fault tolerance)
• Product lifecycle or system lifecycle requirements

In some cases, the standard may also specify requirements for software or firmware development processes, configuration management, or verification and validation (V&V) of programmable systems.

Functional safety standards typically define a structured safety lifecycle that includes:

• Hazard analysis
• Safety concept
• System design
• Verification and Validation
• Operation and maintenance
• Modification and decommissioning

Look for Mandatory Performance or Safety Integrity Levels

Some product standards explicitly require a minimum safety rating for safety functions.

When a standard directs you to determine or achieve one of these levels, functional safety is not optional – it is a mandated part of the compliance approach.

For example:

• IEC 61508 SIL levels (Safety Integrity Level) – SIL 1 through SIL 4
• ISO/EN 13849-1 Performance Levels (Performance Level) – PLa through PLe
• ISO 26262A SIL levels (Automotive Safety Integrity Level) – ASIL 1 through ASIL 4
• IEC/UL 60730-1, IEC/UL 60335 (Annex R), CSA C22.2 No. 0.8 Classes – Class B, C
• UL 1998 Classes – Class 1, 2

Recognizing Functional Safety Requirements Even When Not Explicitly Named

Certain standards avoid using the term “functional safety” yet still require its principles. Indicators often appear in phrases such as:

• “A safety analysis consisting of a hazard identification, risk analysis and risk evaluation shall be
• conducted on the device under test”
• “The control system shall ensure safe operation under fault conditions.”
• “The system shall transition to a safe state.”
• “Fault detection and diagnostics shall be implemented.”
• “Redundancy or monitoring is required to achieve the required reliability.”

These requirements reflect core functional safety concepts, even when they are not labeled as such.

When Uncertain, Apply a Risk‑Based Approach

A simple guiding principle can help clarify the need for functional safety:

If a failure of an electronic control or control system could result in an imminent hazard to people or the environment, functional safety is required.

This principle applies across all sectors – including appliances, machinery, automotive, robotics, process control, medical devices, and many others – regardless of the specific product or application.

Final Thoughts

Determining whether functional safety is required is not about locating a single definitive statement within a standard. It is about recognizing the indicators:

• Does the standard address electronic controls or safety‑related control systems?
• Does it require risk reduction measures implemented through control functions?
• Does it reference SIL, PL, ASIL, or Class levels?
• Does it mandate lifecycle processes, diagnostics, or fault tolerance design?

If the answer to any of these questions is yes, the product falls within the scope of functional safety.

Functional safety is more than a compliance obligation; it is a disciplined engineering methodology that ensures technology behaves safely – even in the presence of faults, failures, or unforeseen conditions.

With automation and connectivity expanding across industries, functional safety has never been more relevant.