NEK 400:2018 English version

Forside NEK 400 2018, engelsk

Electrical low voltage installations

NEK 400 deals with the design and construction of electrical low voltage installations. The collection sets requirements for satisfactory electrical safety, as well as laying down guidelines for the design of low voltage electrical installations. NEK 400 is intended for daily use in all installation- and consulting engineering companies operating within the scope of the collection.

NEK 400 is a processed Norwegian edition of the IEC 60364 series, the CENELEC HD 60364 series and some complementary national standards. The purpose of the collection is to contribute to satisfactory safety and function of electrical low voltage installations in the design and installation. The collection also includes method for initial and periodic verification.

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About the product

NEK 400 is also an important “contractual document” between the customer who order an electric low voltage installation and the professional suppliers. An electrical low voltage installation should be designed and executed in accordance with NEK 400, to ensure that the customer receives a satisfactory quality delivery and that it meets the regulatory requirements. Suppliers of equipment within the market segment “low voltage installations” should also have good knowledge of the requirements set by NEK 400, so that they are familiar with the framework conditions for their equipment.

The relationship between the standard and legislation

NEK 400 is the central reference basis in national regulations on electrical low voltage installations. The regulations are laid down by the national electrical safety authority in this area – the Directorate for Civil Protection and Emergency Planning (DSB). The authorities state that regulations, guidelines for regulations and NEK 400 collectively specify the minimum level of safety required. The collection also includes methods for final inspection and periodic verification of low voltage electrical installations. Companies that plan and carry out installation of electrical installations shall, in accordance with the regulations, issue a declaration of conformity where they confirm that the regulations have been fulfilled, and must, if NEK 400 is used as the basis for the work, specify which edition of NEK 400 is used.

Electric low voltage installations are subject to supervision by the Local Electricity Inspectorate (DLE). They control that those who design and perform such installations are qualified and deliver electrical installations in accordance with the regulations. Since “all” executives in practice use the current version of NEK 400, the authorities will in practice verify that the deliveries are according to the safety level of NEK 400 to bring Norwegian practice into line with internationally recognized practice.

Declaration of conformity – an important document for the customer

A Declaration of Conformity will, for the customer, confirm that the low voltage electrical installation is delivered in accordance with the requirements of the standard collection (or specified parts thereof). Such a declaration will then be part of the private agreement between supplier and customer.

Questions and answers

The national comittee NK 64 has for several years received and processed questions about interpretation of NEK 400. Furthermore, the committee has handled over 700 questions / answers that are collected in a FAQ database (in Norwegian only).


NK 64 has interpreted the wording in some sections of NEK 400. These are searchable through the above-mentioned question / answer database, but are also collected on a separate page. (In Norwegian only). Interpretation is normally of a fundamental nature and will thus be particularly important to note. Be aware of the date on which the interpretation has been made, as this basically applies to the mentioned edition of NEK 400. In most cases, however, the interpretation will also be relevant for later editions.

NEK 400 releases

A new edition of NEK 400 is released every four years. The first time was in 1998, since 2002, 2006, 2010, 2014 and now in 2018. The next edition comes in 2022. The authorities on electrical safety have had the practice to allow one year of transition time before they “require” that the requirements in the new edition is to be used . This means that customers can receive an electrical installation according to “old standard” for a while after the new NEK 400 is launched, unless otherwise specified in the agreement.