NEN 3140 inspector: which qualification do you need?

An inspector is the person who tests electrical equipment. That person must be able to show what they do: know the inspection requirements, measure, assess and record the result. Under NEN 3140, competence comes down to a written designation from the employer. The Arbobesluit (Dutch Working Conditions Decree) only requires a competent person or body in article 7.4a. See the inspection page for the method and the VP and VOP page for the designation. If you outsource, check SCIOS Scope 9 .

The word “keurmeester” (inspector) does not appear in the Arbobesluit. Article 7.4a, paragraph 5, requires a “deskundige natuurlijke persoon, rechtspersoon of instelling” (competent natural person, legal entity or institution). The law does not name a diploma or a national register. What your employer or client accepts beyond that, you record in the designation or in the choice of a certified inspection company.

What must an inspector be able to do?

An inspector must demonstrably master five things. Each one has evidence that an auditor can check.

Component	What they can demonstrate	Where you find the evidence
Standard	Know and apply the inspection requirements from NEN 3140	Training certificate or internal test
Measuring	Measure insulation resistance, earth continuity and leakage current	Calibration certificate of the measuring device
Visual check	Assess cable, plug, housing and rating plate	Inspection form
Assessment	Pass or fail, with a reason	Inspection register
Recording	Record every inspection with date, result and name	Inspection register or digital system

The measurement needs the most attention. A measuring device that is not calibrated makes the result worthless, even if the inspector works carefully.

Inspect in-house or outsource?

You can do the inspection yourself with an employee, or you can hire an inspection company. Both work, but they ask different things of you.

	In-house: your own inspector	External: inspection company
Who	Employee with a designation	Company with a SCIOS certificate, preferably for Scope 9
Evidence	Your own designation and register	The company’s certificate and report
Strong with	Your own organisation	Clients and insurers
Watch out for	Monitoring training, calibration and continuity	Agreeing the scope and interval clearly

With an in-house inspector, the designation is the document that counts. With an external company, that company’s certificate is the document that counts.

Example: an inspector at a metal company

This is a fictional example. A metal company with 25 employees uses about eighty pieces of hand tools. The technical department appoints one employee as inspector for those tools. The designation states which types of tools they may inspect, which measuring device they use and how they record results.

They inspect using a fixed working method: first the visual check, then the measurement, then the function test. Each device receives a label with a date and initials. The inspector signs the register. The company has the installation responsible person (IV) check the designation every year.

An employee can inspect the tools, as long as the competence is on paper and the register is complete.

What an auditor or inspector wants to see

A written designation with the name of the inspector, the types of tools and the date.
A working method that records which checks and measurements you carry out.
The calibration certificate of the measuring device.
An inspection register that lists each device with its date and result.
Failed items with a reason, and what happened to them afterwards.

Common mistakes

Someone inspects without a designation because they know about electrical equipment.
The measuring device is not calibrated, or the calibration certificate is missing.
The register is incomplete: no date, no name, no result.
A sticker is put on without any record.
The designation is never reviewed, even after a change in the tools.

Frequently asked questions

Does an inspector need a diploma?

No, the law does not require a diploma. Article 7.4a requires a competent person. What counts is proven knowledge and a designation. Ask your employer, client or insurer what they accept.

Is an inspector course the same as a designation?

No. A course is training and gives you knowledge. The designation is issued in writing by your employer. Read more on the page about NEN 3140 courses.

May I inspect my own equipment?

Yes, as long as your designation and your register are in order. The Arboportaal (Dutch occupational health portal) lists your own technical department as an option alongside an external company. An external inspection carries more weight with third parties. See SCIOS Scope 9 for what a certified inspection involves.

What does an inspection by an external company cost?

It depends on the number of devices and your region. See the costs page for price indications.

How do you record the designation?

A designation for an inspector is short, but it must be specific. This is a fictional example of the content.

Part of the designation	Example
Name and role	J. de Vries, technical department employee
Types of tools	Hand tools for construction and workshop use, no large machines
Measuring equipment	Measuring device with asset number 14, calibrated every year
Working method	Visual check, measurement, function test, then label and register
Recording	Inspection register, digital or on paper, kept by the inspector
Review	Every year by the installation responsible person, or after a change
Date and initials	Date of signature by the employer

A designation that only says “may inspect” is too vague. An auditor wants to know exactly what is allowed and how that is recorded.

When should an inspector be reassessed?

The tools change, for example when new devices with a different plug type arrive.
The inspector leaves, or takes on a different role.
The measuring device is replaced.
After a deviation in an inspection that was not followed up.

Record the date of each assessment in the designation. That way it is clear when the inspector was last checked.