Guide

Installation methods under the AREI: which entry belongs on the single-line diagram?

The seventeen installation methods of sub-section 5.2.2.1, their specific rules in section 5.2.9, how they govern current-carrying capacity and where the entry is actually mandatory — with the AREI article next to every statement.

Published on 31 August 2026 12 min

Which installation methods does the AREI recognise — and which one belongs on the diagram?

The AREI lists the permitted installation methods for low-voltage wiring exhaustively: seventeen letters, a to q, in sub-section 5.2.2.1 — overhead lines, buried cables, surface and concealed wiring, skirtings, trunking and troughs, all the way to heating cables in ceilings and floors. For most of these methods, section 5.2.9 adds its own binding rules. And the chosen method is not the installer's private business: the single-line diagram of a domestic installation must state, alongside type, cross-section and number of conductors, the installation method of the wiring (sub-section 3.1.2.2 point a).

The reason sits elsewhere in the regulation. The current-carrying capacity IZ of a cable depends, among other things, on "the installation method and the environment of the wiring" (sub-section 4.4.1.4). Without the installation method you cannot judge whether a cross-section suits the circuit — which is exactly why it is on the diagram.

Letter (5.2.2.1)	Installation method	Typical residential use	Specific rules
a	overhead lines	supply to an outbuilding	5.2.9.1 (refers to book 3, chapter 7.1)
b.1	directly buried	garden socket, carport	5.2.9.2 point a: at least 0.60 m deep, cables only
b.2	buried with mechanical protection	cable under a warning tape	5.2.9.2 point a
b.3	buried in ducts	crossing under a driveway or terrace	5.2.9.2 point a
c	contact lines for rolling or sliding contacts	not relevant in housing	5.2.1.4 point a
d	surface-mounted	visible XVB in cellar, garage, plant room	5.2.9.5: cables only; wall clearance ≤ 0.3 × outer diameter
e	in concealed conduits	new-build standard: VOB inside Preflex	5.2.9.3
f	in mouldings, skirtings and architraves	renovation, visible trunking	5.2.9.4: insulated conductors or single-core cables only
g	in free air with clips, or on trays, ladders, brackets and similar supports	plant room, boiler room	5.2.9.5: clearance from any wall ≥ 0.3 × outer diameter
h	in trunking and troughs	distribution run in a plant room	5.2.9.6: troughs take cables only
i	in ducts above floor level	route above the floor	5.2.9.7
j	in open, closed or sand-filled channels	floor channel, industrial use	5.2.9.8
k	in structural voids, recesses and manufactured blocks	hollow blocks, suspended ceiling	5.2.9.9 and 4.3.3.5 point b
l	behind wall panels	drywall, timber frame	5.2.9.9 and 4.3.3.5 point b
m	directly concealed, without conduits	XVB straight into the chase	5.2.9.10: installation zones, concrete ≥ 3 cm, plaster ≥ 0.4 cm
n	in busbar trunking systems	rare in housing	5.2.9.11
o	on insulators	legacy installations	5.2.9.12
p	submerged in water	swimming-pool equipment	5.2.2.1 point p
q	in ceilings, floors and walls for heating cables and panels	underfloor heating, heating mats	5.2.9.13

Other methods are not forbidden, but they fall under the residual clause: they must comply with "the relevant rules of the trade" (sub-section 5.2.2.4). Working outside the list therefore means leaving the territory for which the AREI itself states a rule.

What separates point e from point m?

This is the pair that gets confused most often, because in everyday speech both are simply "concealed". The difference is the conduit. Point e is literally "in concealed conduits" — the Dutch text says "in verzonken buizen", the French "sous conduits encastrés". Point m is expressly "directly concealed, without conduits".

That is not wordplay but the boundary between two sets of rules. Point e is governed by sub-section 5.2.9.3 with the conduit rules: bending radii, conductors that remain drawable and removable at all times, no connections inside the conduit. Point m is governed by sub-section 5.2.9.10 with the installation zones and the minimum covers. Which material to choose in each case, and what it costs, is compared in Preflex versus open wiring; this article describes the systematics that both variants sit inside.

Why does the installation method govern current-carrying capacity?

Sub-section 4.4.1.4 names five quantities that IZ depends on. The installation method is one of them, and it is the only one you cannot read off the cable itself.

Quantity per 4.4.1.4	What it means on the plan
conductor cross-section	entry on the single-line diagram (3.1.2.2 point a)
conductor insulation	cable type, for example XVB or VOB
construction of the wiring	single- or multi-core, armouring, screen
installation method and environment	entry on the single-line diagram (3.1.2.2 point a)
ambient temperature	where the cable runs, see 5.2.3.1

The calculation itself is not in the AREI. The text only says that current-carrying capacity "is calculated in accordance with the rules of the trade" (4.4.1.4), and that the competent ministers may set out further rules. In practice the tables and correction factors therefore come from the NBN HD 60364-5-52 series, not from the AREI.

What the AREI does fix is frequently mistaken for that: table 4.11 gives, for domestic installations, the maximum rated current per conductor cross-section, separately for the fuse and for the circuit breaker: at 1.5 mm² 10 A and 16 A, at 2.5 mm² 16 A and 20 A, at 4 mm² 20 A and 25 A, at 6 mm² 32 A and 40 A, at 10 mm² 50 A and 63 A. That table knows nothing about the installation method. It is a ceiling, not a clearance: the condition IZ ≥ IB from sub-section 5.2.1.2 point a has to be met on top of it. The cross-section-to-protection pairing is covered in Cable cross-section and breaker rating.

What do grouping, ambient temperature and thermal insulation do to the capacity?

All three lower IZ, and in all three cases the AREI supplies the boundary condition, not the factor.

Grouping. The AREI defines the threshold precisely: a cable or insulated conductor counts as installed separately when it lies at least 20 mm away from any other cable or insulated conductor (section 2.7.1). Anything closer is installed "in bunches or in a flat layer". That distinction has a direct consequence in the AREI — but for fire propagation, not for heating: separately installed conductors and cables must have at least characteristic F1 or class Eca (sub-section 5.2.7.2); in bunches or a flat layer, at least F2 or class Cca (sub-section 5.2.7.3), and that applies "regardless of the distance over which" they are actually bunched. The thermal grouping factor itself again follows from the rules of the trade.

Ambient temperature. Sub-section 5.2.3.1 requires wiring to suit both the lowest and the highest local ambient temperature and to be installed only within the temperature range stated by the manufacturer. Section 5.2.8 adds to this: wiring must not be exposed to harmful temperatures near heating pipes, hot-air ducts or flues, and must keep sufficient distance or be separated by a heat shield. Routing a cable alongside the heating manifold changes its thermal environment — and that environment is part of the same entry as the installation method.

Thermal insulation. Here an honest statement is due: the AREI contains no reduction factor of its own for cables in or under thermal insulation. "Thermal insulation" appears in the regulation as a precaution for temperatures below −25 °C (5.2.3.1) and in the chapter on heating panels, where insulating material in contact with the heating installation must be non-combustible (5.2.9.13 point b.5). A cable running through an insulated pitched roof therefore falls under "installation method and environment" in 4.4.1.4 and is assessed by the rules of the trade — not by an AREI table that does not exist.

Where does the entry belong: single-line diagram, position plan or bill of materials?

These three documents have clearly separated mandatory content in the AREI.

Document	Installation method required?	Reference
single-line diagram (domestic)	yes, explicitly	3.1.2.2 point a
position plan (domestic)	no — it shows the position of the components	3.1.2.3 point a
circuit diagram (non-domestic)	yes, together with length and conductor count	3.1.2.2 point b
bill of materials	not prescribed	permitted as an annex under 3.1.2.1 point c

The bill of materials is not a mandatory document under the AREI. Sub-section 3.1.2.1 point c merely allows diagrams and plans to be supplemented by documents "describing in more detail the various characteristics of the electrical equipment and/or products". A cable list carrying the installation method per run is exactly such an annex: useful for pricing and execution, but it does not remove the obligation to carry the entry on the single-line diagram itself.

How diagram and position plan divide the work is set out in Cable routes and cable lengths, which also explains why the length is mandatory only on the non-domestic circuit diagram.

When does the installation method change within one cable run?

A cable run rarely has a single installation method. Out of the board, through the wall, across the ceiling, into the ground and back up an outside wall — that is four. The AREI has a term for this. The origin of the circuit is either the start of the wiring "or the point where the cross-section, nature or construction of the wiring, or its installation method, changes" (section 2.6.1).

In practice: every change of method opens a separate stretch for assessment. For sizing, the least favourable one governs — a cable that runs two metres inside a bundle of conduits before continuing freely across a ceiling is not sized on the free stretch. For the diagram: every method that occurs must be documented, not just the longest one.

Which rules apply to concealed wiring?

For direct concealment without conduit (point m), sub-section 5.2.9.10 is the governing provision, and it is unusually concrete.

Wiring embedded in concrete or cement is covered by a layer of at least 3 cm; conductors with basic insulation only may not be embedded there at all (point a).

Wiring concealed without conduit in the walls of rooms must additionally stay within the installation zones (point b):

the route consists exclusively of horizontal and vertical stretches, horizontal runs in a ceiling being perpendicular to the vertical walls;
horizontal runs lie 25 to 35 cm above the floor or below the ceiling, and likewise 25 to 35 cm above the underside of window lintels, provided they then remain at least 25 cm below the ceiling;
vertical runs lie as close as possible to a corner of the room, or 10 to 20 cm from door frames and architraves;
outside these zones, only a vertical run above a visible machine or appliance is permitted;
the wiring is subjected to no mechanical stress, neither during installation nor afterwards, and is fixed to the walls without damage;
the covering plaster layer is at least 0.4 cm thick.

For conduits, sub-section 5.2.9.3 applies instead: conductors or cables must remain drawable and removable at all times (point e), connections inside the conduit are forbidden (point f), and in embedded conduits tees and elbows are not permitted while conductors stay accessible in junction, branch and draw boxes (point i.2). Conduits made of combustible material may only be used when embedded at least 3 cm deep in non-combustible materials (point f).

One important exception: for extra-low voltage installations, the zone pattern of 5.2.9.10 point b expressly does not apply (sub-section 5.2.9.15 point b). Bus, bell and control wiring at ELV therefore need not follow the zones — the remaining rules of section 5.2.9 still do.

What applies to buried cables?

Sub-section 5.2.9.2 point a is one of the sharpest provisions in the chapter. In the ground and in inaccessible underground ducts, only cables may be installed, independent protective conductors excepted. The minimum depth is 0.60 m measured from the ground surface, "unless technically impossible". Where that depth cannot be reached, protection is provided instead by a continuous or sealed duct of durable, resistant material.

The cable must additionally satisfy one of three conditions: an earthed electrical screen with armouring or a reinforced outer sheath; or a resistant outer sheath plus a continuous cover that protects against tools during excavation and overhangs on both sides; or installation in a duct or an equivalent system. Once one of these is satisfied, no additional measures are required for protection against electric shock.

For marking in the ground, point d carries its own rules: markers at the ends of straight sections, at least every two hundred metres, with a surface of at least 0.01 m² and a lightning symbol in relief. Connections of low-voltage network users are exempt.

Which cable is allowed in which installation method?

The installation method restricts the choice of cable, independently of cross-section.

Installation method	Permitted	Reference
buried	cables only	5.2.9.2 a
in free air and surface-mounted	cables only	5.2.9.5
trough	cables only	5.2.9.6
trunking	insulated conductors as well; outside electrical service rooms with solid walls and a lid that opens only with a tool	5.2.9.6
mouldings, skirtings, architraves	insulated conductors or single-core cables	5.2.9.4 b
conduits	insulated conductors or cables	5.2.9.3 b
structural voids	no conductors with basic insulation only	5.2.9.9

On top of that comes the reaction-to-fire class. In structural voids and in mouldings, skirtings or architraves made of combustible materials, sub-section 4.3.3.5 point b expressly requires the characteristic or class of 5.2.7.3 — that is, F2 or at least Cca. A timber-stud wall is a structural void. Which cable type suits which use is covered in XVB versus VOB; for wet rooms the volume rules from Bathroom cables and AREI zones apply on top.

How does PlanElec record the installation method, and what appears in the export?

PlanElec knows twelve installation methods relevant to housing and stores the AREI reference each one sits under:

Choice in PlanElec	Short code	Stored AREI reference
surface-mounted	AP	5.2.2.1 d
surface-mounted conduit	AR	5.2.2.1 d / 5.2.9.3 h
concealed in flexible conduit	UR	5.2.2.1 e
concealed direct	UD	5.2.2.1 m
in conduit	IR	5.2.9.3
bundle of conduits	RB	5.2.9.3
hollow wall / wall panel	HW	5.2.2.1 k + l
skirting / cable trunking	FL	5.2.2.1 f
underground	EV	5.2.2.1 b.1 + b.2
underground in cable conduit	ER	5.2.2.1 b.3
cable tray / ladder	KW	5.2.2.1 g + h
free in ceiling or cavity	FV	5.2.2.1 g

The method is attached to the segment, not to the whole cable: a route on the floor plan can carry a different method per stretch, and each stretch is drawn in its own colour with the two-letter short code. On the single-line diagram, one governing method is drawn by default — the most restrictive of those present. Methods for which the tool holds no reliable reference table are deliberately given priority instead of being hidden behind an invented thermal ranking.

Since the update of 28 August 2026, cables in conduit, bundles of conduits, buried cables in a duct and surface conduits can be selected separately; each installation method carries the same complete sign with its own carrier line in the cable menu, the editor, the preview and the PDF. That carrier line is precisely what makes surface and concealed distinguishable: it represents the conductor, and which side the wall marks sit on is the statement. Since 29 August 2026 the installation method can be clicked directly in the diagram; the cable menu opens at the chosen spot and remains available in the properties panel. In the cable list it appears as its own column, "Installation method".

What the AREI self-check does not cover here

The self-check is indicative. For the installation method that means, concretely:

It does not check current-carrying capacity under the recorded installation method. What is checked is whether the cable cross-section matches the rated current of the protective device — that is the pairing from table 4.11, which ignores the installation method. Grouping, ambient temperature and insulation enter no check at all.
It does not check whether the installation zones of 5.2.9.10 point b are respected, whether the plaster or concrete cover is thick enough, or whether a buried cable lies deep enough. Those are site dimensions, not model data.
It does check one method-dependent rule: cables installed in structural voids must run in a conduit or reach at least class Cca (4.3.3.5 point b / 5.2.7.3). If the fire class is missing, PlanElec reports a data gap rather than an error; if it is below Cca with no conduit documented, it is an error.
It does not check whether the recorded installation method matches what was actually installed later. That is a visual finding on site.
It replaces neither measurement nor inspection; the official assessment rests exclusively with an approved body. The full scope is listed in What the self-check verifies.

Which mistakes show up at inspection?

Insulated conductors instead of cables, surface-mounted or in a trough. Loose VOB cores visible on a wall or lying in a trough breach 5.2.9.5 and 5.2.9.6 respectively: only cables are admitted there.
Chase outside the installation zones. Diagonal runs and routes straight across the middle of a wall are the classic finding under 5.2.9.10 point b.
Cover too thin. Less than 0.4 cm of plaster over the cable, or less than 3 cm of concrete for embedded wiring (5.2.9.10 points a and b).
Connection inside the conduit. Terminals and connectors within a conduit are forbidden (5.2.9.3 point f); connections in draw and junction boxes belong on a suitable terminal block.
Conduit no longer drawable. Tight bends or overfilled conduits breach the requirement that conductors can be drawn in and removed at any time (5.2.9.3 point e).
Structural void with Eca instead of Cca and no conduit. A frequent finding in timber frame and suspended ceilings (4.3.3.5 point b / 5.2.7.3).
Buried cable too shallow. Less than 0.60 m without a continuous protective duct (5.2.9.2 point a).
Installation method missing from the diagram. A single-line diagram carrying type, cross-section and conductor count but no installation method is incomplete (3.1.2.2 point a) — however cleanly the installation itself was executed.