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IEC 61310-2:2007 — Safety of Machinery — Indication, Marking and Actuation
A Comprehensive Technical Guide for Machine Designers and Safety Engineers
Key Standard: IEC 61310-2:2007 specifies requirements for the indication, marking and actuation of machinery. It ensures that operators receive clear, unambiguous safety information through visual, audible and tactile means, and that actuation devices (pushbuttons, pedals, handles) are designed and positioned to prevent inadvertent operation.
1. Scope and Core Principles
IEC 61310-2 is part of the IEC 61310 series on safety of machinery, addressing how machines communicate safety-critical information to operators. Unlike IEC 61310-1 which focuses on general marking principles, Part 2 specifically covers actuation devices and their relationship to indication and marking. The standard applies to all machinery where operator interaction is required, from simple workshop tools to complex automated production lines.
The core principle is that machine operators must be able to clearly identify controls, understand their function, and receive unambiguous feedback about machine status. This is fundamental to preventing accidents caused by operator confusion or misinterpretation of control functions.
Critical Safety Gap: Many industrial accidents occur because operators actuated the wrong control or misread a machine’s status indication. IEC 61310-2 directly addresses these failure modes through systematic design requirements.
2. Technical Requirements for Indication and Marking
2.1 Visual Indicators
The standard specifies colour coding for visual indicators based on IEC 60073. Red indicates emergency or fault conditions, yellow/amber denotes caution or abnormal conditions, green signifies normal operation, and blue indicates mandatory action. White/clear is used for general information where no specific colour coding is needed. Each indicator must be clearly labelled and positioned within the operator’s normal field of view.
2.2 Marking Durability and Legibility
All markings must remain legible throughout the expected lifetime of the machinery under normal operating conditions. The standard requires that markings resist fading, abrasion, chemical exposure, and cleaning processes. Minimum character heights are specified based on viewing distance — for example, a viewing distance of 1 metre requires characters at least 5 mm high under normal lighting conditions.
| Viewing Distance (m) | Min. Character Height (mm) | Typical Application |
|---|---|---|
| 0.5 | 3.0 | Control panel labels |
| 1.0 | 5.0 | Machine nameplates |
| 2.0 | 10.0 | Large machine markings |
| 4.0 | 20.0 | Overhead crane markings |
| 8.0 | 40.0 | Building-level signage |
3. Actuation Device Design Requirements
3.1 Pushbuttons and Control Actuators
IEC 61310-2 classifies actuation devices by their physical action: momentary (spring-return), maintained (latching), and emergency (break-return). Emergency stop actuators must be red with a yellow background, mushroom-headed, and remain latched until manually released. Start actuators must be recessed or guarded to prevent accidental operation where unintended activation could create a hazard.
The standard mandates that actuation forces follow ergonomic ranges. Pushbuttons should require between 2.5 N and 15 N force. Foot pedals should require 10 N to 60 N depending on frequency of use — lighter forces for frequently operated pedals, higher forces for safety-critical pedals to prevent accidental actuation.
3.2 Prevention of Inadvertent Operation
A critical engineering requirement is that actuation devices must be designed, positioned, and guarded to minimise the risk of inadvertent operation. This includes requirements for recessed buttons, two-step actuation (e.g., push-and-turn), protective shrouds, and logical grouping of related controls. The distance between adjacent controls must be sufficient to prevent simultaneous unintended actuation — typically a minimum of 25 mm for pushbuttons operated with fingers.
Design Insight: When designing machine control panels, group emergency controls in a dedicated zone separated by at least 50 mm from normal operating controls. Use tactile differentiation (raised edges, different surface textures) to allow blind identification. Consider that operators wearing gloves (common in industrial settings) require larger minimum dimensions and higher actuation forces.
4. Emergency Stop and Safety-Related Functions
The standard dedicates significant attention to emergency stop actuation. Emergency stop devices must be easily accessible, clearly identifiable, and operate independently from the normal control system. They must use direct opening action (positive opening) of switch contacts as specified in IEC 60947-5-1 and IEC 60947-5-5. The red actuator with yellow background colour combination is internationally recognised and must not be used for any other function.
For machinery with multiple operating positions or large dimensions, multiple emergency stop devices are required. The maximum reach distance to any emergency stop device should not exceed 2.5 metres from any operator position.
Non-Compliance Risk: Using the red/yellow emergency stop colour combination for any non-emergency function is a common but dangerous design error. This desensitises operators to the emergency stop signal and may cause delayed response during actual emergencies.
5. Engineering Implementation Guidelines
When integrating IEC 61310-2 requirements into a machine design, consider these practical engineering aspects:
- Environmental factors: Illumination levels, ambient noise, and vibration affect the perception of indication devices. Select indicator brightness and acoustic signal levels accordingly — for example, audible alarms should be at least 10 dB above ambient noise.
- Cultural considerations: Symbol-based markings should be used wherever possible to overcome language barriers. Where text is used, multiple languages may be needed depending on the machine’s operational location.
- Lifecycle marking: Consider that markings may need to be replaced during machine refurbishment. Use modular label systems that allow easy replacement without damage to painted surfaces.
- Integration with functional safety: Indication and actuation devices that are part of safety functions must comply with the relevant SIL or PL requirements of IEC 62061 or ISO 13849.
| Safety Function | Actuator Type | Colour | IEC Reference |
|---|---|---|---|
| Emergency Stop | Mushroom-head, maintained | Red on yellow | IEC 60947-5-5 |
| Start / On | Momentary or maintained | Green, white, or grey | IEC 60073 |
| Stop / Off | Momentary | Red, black, or grey | IEC 60073 |
| Jog / Inch | Momentary, guarded | Blue, white, or grey | IEC 61310-2 |
| Reset | Momentary | Blue, white, or grey | IEC 61310-2 |
6. Frequently Asked Questions
Q: Can I use illuminated pushbuttons for both indication and actuation?
A: Yes, but the illumination colour must follow the function’s colour code. For example, a green illuminated button can serve as both the start actuator and the “running” indicator. However, ensure that the illumination function does not interfere with the tactile identification of the button.
Q: Are foot-operated pedals covered by IEC 61310-2?
A: Yes, foot pedals are specifically addressed. They must be designed to prevent accidental operation by requiring intentional force, and the actuation direction should be predictable (typically downward pressure). Pedals used for safety functions require protective covers or shrouds.
Q: What are the testing requirements for marking durability?
A: The standard references relevant test methods including abrasion testing (typically using a standard eraser or brush), chemical resistance testing (using common industrial cleaning agents), and UV exposure testing for outdoor machinery. Specific acceptance criteria should be agreed between manufacturer and customer.
Q: How does IEC 61310-2 relate to the EU Machinery Directive?
A: IEC 61310-2 is harmonised under the EU Machinery Directive (2006/42/EC) as a Type B standard. Compliance provides presumption of conformity with the relevant essential health and safety requirements. Machine manufacturers placing products on the EU market should apply this standard as part of their conformity assessment.
