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Periodic inspection according to NEN 3140

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Periodic inspection — NEN 3140

NEN 3140 requires employers to carry out periodic inspections of electrical installations and equipment (Occupational Safety and Health Decree, articles 3.4 and 7.4a).

Inspection intervals (guideline)

ObjectLow riskHigh risk
Fixed installation office5 years1–3 years
Fixed installation industry / greenhouse3 years1 year
Extension cords construction site—3 months
Hand tools (class I)1 year6 months
Hand tools (class II)2 years1 year
Insulating glovesBefore each use (visual + air test)Lab test approx. 6 months (IEC 60903)
Measuring instruments (calibration)1–2 years1 year
Earthing setAnnuallyAnnually

Insulating gloves are self-checked before every use with a visual inspection and an air test (rolling them up and checking for leaks); in addition, a periodic laboratory test per IEC 60903 is required, typically every 6 months. Measuring instruments (installation tester, insulation tester, low-resistance ohmmeter) must be calibrated periodically to guarantee measurement accuracy; earthing sets are checked annually, both visually and electrically, for continuity and terminal damage.

Inspection Components

  1. Visual — damaged insulation, overheating, correct labeling.
  2. Measurement — insulation resistance, earth connection, leakage current, RCD operation.
  3. Documentation — installation responsible person (IV), work responsible person (WV), logbook.

Reporting

  • Results are recorded in an inspection report detailing deviations, priority, and restoration deadlines.
  • Responsible party: Installation Responsible Person (IV) — appointed in writing.

Further reading

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Periodic inspection according to NEN 3140 · NEN-Hub