Four-eyes principle
Vier-ogen principe
Also known as: vier-ogen, double-check, two-person-check, four-eyes, four-eyes-principle, vierogenprincipe
Risk mitigation where a designated second person visually verifies the switching action or measurement. Mandatory in NEN 3140 for work near or under voltage and for releasing an installation after maintenance.
Practical example
Two-man rule: After maintenance, a second VP confirms all tools are removed and locks disengaged before re-energizing.
Common mistake
Two-person principle. Common mistake: Working live alone without a second person present—no one to intervene or call for help in case of an incident.
See also
Related terms
In-depth guides
- → ISO 14119 Guard interlocking and locking switches — four types per ISO 14119
- → IEC 61230 (aardingsset) Earthing and short-circuiting sets — periodic testing per IEC 61230
- → Inspectie Testing the RCD — trip time and residual current (NEN-EN-IEC 61557-6)
- → Inspectie ATEX explosion-hazard zones — classification & inspection
- → IEC 60079-14 ATEX cable entries — why an Ex e gland does not simply fit onto an Ex d enclosure
- → IEC 60079-0 Decoding the ATEX Ex marking — what does "Ex db IIC T4 Gb" mean?
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