ISO 11428:1996

Overview

ISO 11428:1996 - "Ergonomics - Visual danger signals - General requirements, design and testing" specifies safety and ergonomic criteria for visual danger signals so they can be perceived, discriminated and acted on within a defined signal reception area. The standard covers design intent, required physical measurements (luminance/illuminance/contrast), subjective visual checks and recommendations for signal behaviour (colour, temporal pattern, location and duration). It excludes written/pictorial indicators, data display units and special public-transport/public-disaster regulations.

Key topics and requirements

• Detectability
  • Distinguishes luminous area vs point sources (visual angle criteria given).
  • For area sources, required luminance ratio (contrast): visual warning ≥ 5× background; visual emergency ≥ 10× background (i.e., emergency ≥2× warning).
  • For point sources, detectability is based on pupillary illuminance relative to background luminance (measurement guidance provided).
  • Flashing is required for emergency signals; recommended flash frequency ~2–3 Hz.
• Discriminability
  • Use at least two distinguishing characteristics (colour, location, temporal pattern, shape).
  • Colour assignment: warning = yellow/yellow‑orange, emergency = red. If colours alone are insufficient, emergency intensity must be ≥2× warning.
  • Relative position: red above yellow when vertically stacked; two red lights horizontally aligned.
• Location & field of vision
  • Signals should be placed within the field of vision of people in the signal reception area; multiple signals may be required so at least one is visible from any point.
• Glare, distance & duration
  • Avoid impairment by glare and limit signal self‑glare.
  • Keep observer distance as short as practicable (illuminance falls with distance squared); consider transmissivity reductions (fog, smoke).
  • After action, downgrade or switch off signals; use an ALL CLEAR signal per ISO 11429.
• Verification
  • Physical measurements (luminance/illuminance/contrast) recommended.
  • Subjective visual check with representative users (include persons >45 years, acuity <0.8, red‑green color defects, users with eye protection). Small groups observed without prior notice; repeat under varied conditions.

Applications

• Design and testing of safety and alarm lighting for: industrial machinery, manufacturing plants, control rooms, fixed installations, machine safety systems and workplace emergency signaling.
• Integrates into safety engineering, human factors/ergonomics assessments, machine design validation and procedural safety audits.

Who should use it

• Safety engineers, ergonomists, control‑room and machine designers, occupational health managers, compliance officers and standards developers implementing visual alarm and warning systems.

Related standards (selection)

• ISO 3864 (Safety colours and signs)
• ISO 11429 (Auditory and visual danger/information signals)
• ISO/TR 12100-2, IEC 73, IEC 1310-1

Keywords: ISO 11428, ergonomics, visual danger signals, luminance, illuminance, contrast, detectability, discriminability, flashing alarm, emergency signal, safety requirements, signal reception area.