Standard · Norway

NEK 400:2026 explained: Norway's wiring rules for homes, IT network included

NEK 400 is the Norwegian wiring standard, and NEK 400:2026 applies to all design and installation work from 1 July 2026. For a home it requires a 30 mA RCD on every final circuit, a stove guard (komfyrvakt), surge protection, minimum socket numbers per room and 30 % spare space in the consumer unit. Many homes still run on a 230 V IT network without neutral.

Updated on 22 September 2026Last checked 22 September 2026NEK 400:2026 · beta

Key facts

01NEK 400:2026 applies from 1 July 2026; the 2022 edition may still be used for design until 31 December 2026, with the work completed before the end of 2027.
02Every final circuit in a dwelling has its own 30 mA RCD (NEK 400-8-823, since 2010), in practice one RCBO (jordfeilautomat) per circuit.
03A stove guard (komfyrvakt) to EN 50615 has been mandatory since 1 July 2010 in every new installation and whenever a new cooker circuit is installed.
04Living rooms and bedrooms need 2 socket outlets per started 4 m²; the consumer unit keeps 30 % spare space.
05Since 2026, PVC-insulated cables are no longer allowed: the minimum fire-reaction class is Dca-s2,d2,a1.

What is NEK 400 and how does it relate to Norwegian law?

NEK 400, “Elektriske lavspenningsinstallasjoner”, is published by Norsk Elektroteknisk Komite (NEK). It is the Norwegian version of the international HD 60364 series plus national parts. The best known for homes is NEK 400-8-823, nicknamed the housing standard (bolignormen), which adds requirements that do not exist in most other countries.

The legal basis is the Regulation on low-voltage electrical installations (forskrift om elektriske lavspenningsanlegg, FEL, FOR-1998-11-06-1060). FEL sets the safety requirements; its § 10 and the guidance from the Directorate for Civil Protection (DSB) name the latest edition of NEK 400 as the preferred way to meet them. FEL also contains Norwegian national adaptations, for example the rule that no neutral conductor is used in an IT system.

NEK 400 editions and transition rules (DSB)
Edition	Applies from	Transition
NEK 400:2026	1 July 2026	Current edition for all design and installation
NEK 400:2022	1 July 2022	Design allowed until 31 December 2026, completion before the end of 2027
NEK 400:2018	1 July 2018	Replaced (allowed until the end of 2022)

Sources: DSB transition rules for NEK 400, NHO Elektro, nek.no. DSB may grant exemptions for large projects.

Main changes in 2026 relevant to homes, according to NHO Elektro and the trade press: PVC-insulated cables are banned, surge protective devices on IT and TT systems must be “fail-safe”, the kitchen socket rule changed, USB sockets (where fitted) must be USB-C, a data outlet no longer needs a power socket next to it, an existing circuit may no longer be reused to charge an EV in a detached garage, and bonding of plastic drains in bathrooms was removed.

The Norwegian IT network, explained simply

Most of Europe distributes power as TN: three phases plus a neutral, 400 V between phases and 230 V between a phase and the neutral. A large part of Norway instead uses an IT network at 230 V between phases, with no neutral conductor (IT-nett). Sources estimate that roughly 70 to 80 % of buildings are still supplied this way, although that figure dates from older surveys; new areas have mostly been built with TN 400/230 V since the 1990s, and NEK 350 (2025) guides conversions from IT to TN.

On IT, a normal 230 V appliance is connected between two lines (L1-L2, L2-L3 or L3-L1), not between a line and a neutral. There is no 400 V.
Because both conductors are live, protective devices must switch both lines: circuits use 2-pole breakers and RCBOs. A 1-pole-plus-neutral RCBO designed for TN is not suitable on IT.
A 230 V circuit on IT uses a cable with two conductors plus protective earth (3G); a three-line circuit uses 4G.
A first earth fault on IT does not trip anything by itself. In a home, safety relies on the 30 mA RCD on every final circuit required by NEK 400-8-823.
An EV charger on IT is usually single-phase between two lines, up to about 7.4 kW (32 A). Three-phase charging on 3 × 230 V is supported by very few cars.

IT and TN supplies in Norwegian homes (Elvia connection examples)
Supply	Voltage	Neutral	Circuit poles (230 V load)	Example capacity
IT (“2×” or “3×” connection)	230 V between lines	No	2-pole, both lines switched	2 × 20 A ≈ 4.5 kW … 2 × 50 A ≈ 11.5 kW
TN-C-S (“4×” connection)	400 V between phases, 230 V phase-neutral	Yes	1-pole + neutral	4 × 20 A ≈ 14 kW … 4 × 80 A ≈ 55 kW
TT	Up to 230 V	—	Protection by RCD only	—

Sources: FEL national adaptations (lovdata), Elvia (capacity per connection). The share of IT supplies is an estimate from older surveys.

Circuits, breakers and the I2 ≤ Iz rule

Norway applies a stricter coordination rule to dwellings: for cables up to 4 mm², the conventional tripping current of the breaker (I2) must not exceed the current-carrying capacity of the cable (Iz), reported as clause 823.433.1. The general HD 60364 rule allows I2 up to 1.45 Iz. In an insulated wall (installation method A1), 2.5 mm² copper carries 19.5 A, so a 16 A breaker only complies if its I2 is about 1.2 × In (19.2 A), as modern RCBOs claim.

Largest breaker per cable size used by Circuia (230 V circuit, method A1, I2 = 1.2 × In)
Copper section	Iz, method A1	Largest breaker	Typical use
1.5 mm²	14.5 A	10 A	Lighting
2.5 mm²	19.5 A	16 A	Socket circuits, washing machine, water heater (varmtvannsbereder)
4 mm²	26 A	20 A	Heating, larger loads
6 mm²	34 A	32 A	Cooker on IT (usual 25 A 2-pole)

The 2.5 mm² value (19.5 A in A1, 27 A clipped direct) comes from Norwegian trade sources; the other Iz values are IEC 60364-5-52 figures awaiting confirmation for NEK 400:2026. Norwegian breaker ratings include 10, 13, 15, 16, 20 and 25 A.

NEK 400 sets no maximum number of sockets per circuit in the public sources we found; Circuia plans about eight per circuit as practice.
A cooker or induction hob on IT is usually a 25 A 2-pole circuit (practice, to be confirmed); on TN it is often three-phase.
Direct electric heating (panel heaters, underfloor heating cables) is very common. Each underfloor heating system (varmekabel) needs 30 mA protection and a documentation sheet.
Whether washing machines, dryers, dishwashers and water heaters must have dedicated circuits is not stated in public sources; dedicated circuits are usual practice.

RCD per circuit, surge protection and the stove guard (komfyrvakt)

Protection required in a Norwegian dwelling
Device	Rule	Since / source
30 mA RCD (jordfeilbryter)	One per final circuit, usually an RCBO (jordfeilautomat), 2-pole on IT	2010, NEK 400-8-823.411.3.3
RCD type	Type A by default; EV charging type B or type A with 6 mA DC detection (RDC-DD)	NHO Elektro; type AC status not confirmed
Surge protection (overspenningsvern)	Mandatory in every low-voltage installation; type 2 in homes, fail-safe on IT and TT since 2026	1 July 2010, NEK 400 443 / 823
Stove guard (komfyrvakt)	Mandatory for new installations and every new cooker circuit, including holiday homes; EN 50615	1 July 2010, elsikkerhetsportalen
Owner's RCD test	Press the test button at least once a year	elsikkerhetsportalen

Surge protection voltage rating: at least 253 V (1.1 × U0) on TN; the minimum for IT is reported inconsistently (350 to 440 V) and must be checked against NEK 400:2026.

The stove guard (komfyrvakt) is a small device that monitors the hob and cuts its supply if it detects overheating or an unattended pan. It is one of the most searched Norwegian requirements because it applies not only to new homes but every time a new circuit is run to the cooker. A sub-board more than 10 m from the main board normally gets its own type 2 SPD, and an SPD in an outdoor cabinet must warn the owner when it fails.

Minimum sockets per room (bolignormen)

Unlike most European standards, NEK 400-8-823 sets minimum numbers of socket outlets (uttak) per room. One outlet is one socket, so a double socket counts as two.

Minimum socket outlets in a Norwegian dwelling (NEK 400-8-823)
Room	Minimum
Living room, bedroom, study, family room (stue, soverom, arbeidsrom, allrom)	2 per started 4 m²
Kitchen worktop (2026, islands included)	2 for the first 2 m, then 1 per additional started metre (our reading of the 2026 rule)
Kitchen, fixed appliances	1 per fixed appliance
Kitchen dining area	At least 4
Entrance and hall (gang, entré)	2 per started 6 m²
Bathroom (bad)	2 (1 if the bathroom is under 3 m²), plus one per fixed appliance
Storage room, laundry (bod, vaskerom)	2
Each balcony or terrace	At least 2
Media location	6
Consumer unit (sikringsskap)	30 % spare space

Source: elsikkerhetsportalen, “bolignormen” (NEK 400-8-823); kitchen rule 2026 from elektro247. Example: a 13 m² bedroom needs 2 × 4 = 8 outlets, i.e. four double sockets.

Bathrooms (våtrom) and underfloor heating

Bathroom zones used by Circuia for Norway (NEK 400-7-701)
Zone	Extent	Minimum IP rating
0	Inside the bath or shower tray	IPX7
1	Above the bath or shower up to 2.25 m	IPX4
2	0.6 m beyond zone 1	IPX4
Sockets	Only outside zone 2	—

These dimensions come from a commercial guide and match HD 60364-7-701; the Norwegian variant in NEK 400-7-701:2026 was not read. Every bathroom circuit is behind a 30 mA RCD anyway.

Underfloor heating cables (varmekabler) must be double-insulated or screened, with the metal mesh or screen earthed, 30 mA protection on each heating circuit, and a documentation sheet for each system. The thermostat of a heating cable stays outside zones 0 to 2.

EV charging (NEK 400-7-722)

Every charging point has 30 mA protection, type B or type A with RDC-DD. Mode 3 with a Type 2 connector is recommended.
The circuit is sized with a load factor of 1 (the charger may draw its full current for hours) unless load management is installed.
Since 2026, an existing circuit may not be reused to charge a car in a detached garage.
On IT, charging is usually limited to about 7.4 kW (32 A between two lines). On TN, three-phase 16 A gives 11 kW and 32 A gives 22 kW.

Who may do the work: the declaration of conformity (samsvarserklæring)

In Norway, electrical installation work is done by an electrical contractor registered in the Electrical Contractors Register (elvirksomhetsregisteret), with a qualified responsible person (faglig ansvarlig). There is no third-party inspection before the installation is used. Instead, the contractor tests the work and issues a declaration of conformity (samsvarserklæring), which has been required for all work since 1 January 1999.

Documents handed to the owner (FEL § 12 and § 13)
Document	Content
Samsvarserklæring (declaration of conformity)	States that the work complies, and which NEK 400 edition was applied
Risikovurdering (risk assessment)	Design assumptions, special conditions, justified deviations
Sluttkontroll (final inspection report)	Visual inspection, measurements and tests
Kursfortegnelse (circuit list)	What each circuit supplies, breaker ratings and cable sizes

The contractor keeps a copy for at least 5 years; the owner keeps the declaration and documentation up to date. The local electrical inspectorate (DLE), run by the network company, carries out random checks of homes.

Planning a NEK 400 installation with Circuia

Choose Norway when you create the project, then the supply: IT 3 × 230 V (no neutral) or TN 400/230 V. On IT the editor gives every 230 V circuit a 2-pole RCBO and a line pair, balances the pairs, checks I2 ≤ Iz for cables up to 4 mm², adds the stove guard and a surge protective device, counts the bolignormen socket minimums room by room and keeps 30 % spare space in the consumer unit. The circuit list (kursfortegnelse), single-line diagram and bill of materials follow.

Open the editor set up for Norway (free, in your browser). Other Nordic countries: Sweden, Denmark, Finland, or the overview of all standards.

Common mistakes

Using 1-pole + neutral RCBOs on an IT supply: both lines must be switched.
Sharing one RCD between several final circuits in a dwelling.
Forgetting the stove guard (komfyrvakt) when running a new cooker circuit.
Protecting 2.5 mm² cable in an insulated wall with a 16 A breaker whose I2 exceeds 19.5 A.
Counting a double socket as one outlet when checking the bolignormen minimums.
Filling the consumer unit without leaving 30 % spare space.
Ordering PVC-insulated cable for work under NEK 400:2026.

Frequently asked questions

What changed in NEK 400:2026?

NEK 400:2026 applies to design and installation from 1 July 2026. For homes, the main changes reported by NHO Elektro are the ban on PVC-insulated cables, fail-safe surge protection on IT and TT systems, a new kitchen socket rule including islands, USB-C for USB sockets, and a ban on reusing an existing circuit for EV charging in a detached garage.

What is the IT network in Norway?

It is a supply system with 230 V between the lines and no neutral conductor, still common in older Norwegian areas. Appliances are connected between two lines, so circuits need 2-pole protection that switches both conductors. A first earth fault does not trip the supply, which is why every final circuit in a home has its own 30 mA RCD.

Is a komfyrvakt (stove guard) mandatory?

Yes. Since 1 July 2010 a stove guard complying with EN 50615 is required in every new electrical installation and whenever a new circuit is installed for the cooker, in all dwellings including holiday homes. It cuts the supply to the hob when it detects overheating.

How many sockets does a bedroom need under NEK 400?

NEK 400-8-823 requires 2 socket outlets per started 4 m² in living rooms, bedrooms and studies. A double socket counts as two. A 10 m² bedroom therefore needs 6 outlets (three double sockets), and a 13 m² bedroom needs 8.

Does every circuit need its own RCD in Norway?

Yes, in dwellings. NEK 400-8-823 requires each final circuit to have its own RCD of 30 mA or less, a rule in force since 2010. The usual solution is one RCBO (jordfeilautomat) per circuit, 2-pole on an IT supply. Owners should test each RCD at least once a year.

Can I do my own electrical work in Norway?

Fixed electrical installation work must be carried out by an electrical contractor registered in the Electrical Contractors Register, who tests it and issues a samsvarserklæring with the risk assessment, final inspection report and circuit list. Never work on live circuits yourself.

Does Circuia certify an installation to NEK 400?

No. Circuia checks a plan against its Norway rules pack, which is in beta and built from public sources, and produces the circuit list, single-line diagram and bill of materials. Only a registered electrical contractor can carry out, test and declare the installation with a samsvarserklæring.

Design aid

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Written by

Circuia team

Written by the Circuia team from the sources listed and from the editor's rules pack for this country: the values in the tables are the ones Circuia uses.

Published 22 September 2026 · updated 22 September 2026

Sources

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