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)

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.

Certification around inspection: SCIOS and STIPEL

Two names that are often confused but cover different things:

• SCIOS — a certification scheme for inspection and maintenance of technical installations (company certification of inspection bodies). For electrical work the relevant ones include Scope 8 (electrical installations), Scope 10 (inspection of electrical equipment for fire risk per NTA 8220) and Scope 12 (solar/PV installations). Check scios.nl for which scope fits your assignment.
• STIPEL — Stichting Persoonscertificatie Elektrotechniek: personal certification for working on or near electrical installations in the energy sector. The STIPEL exam has a theoretical and a practical part and sets higher requirements than a regular NEN 3140 exam. Training providers state a validity of three years; check the current conditions with STIPEL or your provider.

Neither replaces the employer's written appointment (see roles and appointment). Whether a client or insurer requires a SCIOS-certified inspection body is set out in the contract or policy terms — ask beforehand.