Guide

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

The installation method belongs on the single-line diagram. All seventeen methods from AREI 5.2.2.1, their rules in section 5.2.9, their effect on current-carrying capacity and typical inspection findings, with the article next to every statement.

Published on 31 August 2026 Updated on 5 October 2026 12 min

AuthorStephan Behm

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

The single-line diagram of a dwelling states the installation method of every cable run, alongside cable type, cross-section and number of conductors (sub-section 3.1.2.2 point a). You choose from the seventeen methods 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. Other methods are permitted under the relevant rules of the trade (sub-section 5.2.2.4). For most of the listed methods, section 5.2.9 adds its own binding rules.

An electrician positions electrical conduits in an unfinished building.

The AREI states no purpose for this requirement, but the technical reason is clear: 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.

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	Definition 5.2.2.1 d: wall clearance ≤ 0.3 × D; 5.2.9.5: in principle, cables only
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	Definition 5.2.2.1 g: clearance from all walls ≥ 0.3 × D; 5.2.9.5: in principle, cables only
h	in trunking and troughs	distribution run in a plant room	5.2.9.6: in troughs, in principle, cables only
i	in cable protection (ducting)	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 permitted, 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	installation method: entry on the single-line diagram (3.1.2.2 point a); environment: not prescribed
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. A larger cross-section does not conflict with table 4.11; the table caps the rated current for each cross-section, not the cross-section selected for a lower rated current. 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. 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, situation 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
situation 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; the entry still belongs on the single-line diagram itself.

How diagram and situation 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 stretch generally governs: under sub-section 5.2.1.2 point a, read with sub-section 4.4.1.4, IZ must reach at least IB; sub-section 4.4.3.1 generally places overload protection where a change reduces IZ for the protected wiring (exceptions: sub-section 4.4.3.3). A cable that runs two metres inside a bundle of conduits before continuing freely across a ceiling is therefore not sized on the free stretch. For the representation, the AREI does not prescribe choosing every method, the longest one or the least favourable one (sub-section 3.1.2.2 point a). As a practical recommendation, document every method that occurs in route order because obligations attach to individual stretches: 5.2.9.5, 5.2.9.9 read with 4.3.3.5 point b, 5.2.9.10, 5.2.7.1 point 3 and 5.2.7.3. The inspector then compares the diagram with the visible installation.

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).

For wiring without conduit in the walls of rooms, the installation-zone rules also apply according to the installation situation (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 (ELV), the zone pattern of 5.2.9.10 point b expressly does not apply (sub-section 5.2.9.15 point b). For ELV, the first paragraph of 5.2.9.5, the second paragraph of 5.2.9.9 and the first paragraph of 5.2.9.12 point a also do not apply (5.2.9.15 point b). Bus, bell and control wiring at ELV therefore need not follow the zones; the other applicable 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	in principle cables only; exceptions apply to certain independent protective, equipotential and earthed active conductors	5.2.9.5
trough	in principle cables only; exceptions apply to certain independent protective, equipotential and earthed active conductors	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 fifteen installation methods and stores the AREI reference each one sits under. The names match the visible options in Edit cable:

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
Behind wall panels	HW	5.2.2.1 l
Skirting / surround	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
Building cavity	FV	5.2.2.1 k
In conduit	IR	5.2.9.3
Bundle of conduits	RB	5.2.9.3
Overhead line	FR	5.2.2.1 a
Cable protection	KS	5.2.2.1 i
Open, closed or sand-filled cable channel	KK	5.2.2.1 j

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, PlanElec draws every method that occurs, in route order, by default; the first method is next to the protective device. From three methods onwards, the mark zone shows two symbols and “+n” for the remaining methods; the legend lists every method present, including those grouped under “+n”. The cable list gives the complete sequence for each cable. The per-stretch assignment remains in the cable model and in the per-stretch review. The cable list (CSV and PDF) records, for each cable, the method and length of every route segment in route order once every segment has an installation method; otherwise, it records the methods present without lengths. If a segment length is unknown, it shows “—”, never 0. It includes only the methods of that cable, not those of other cables in the same branch; the total cable length remains available in the length column. It can serve as a supplementary document under sub-section 3.1.2.1 point c.

The symbols use the geometry from table 2.23 category C: the circle on the carrier line is reserved exclusively for the overhead line; the conduit circle sits beside the carrier line. Building cavity, cable tray, cable channel and cable protection have no dedicated symbol in table 2.23, so each receives its own clearly identifiable symbol with a legend in the diagram and PDF output (sub-section 3.1.2.1 point a). The cable menu, editor, preview and PDF use the same symbol source and carrier line.

In edit mode, click the wiring directly in the single-line diagram, even when no installation method has been documented yet; its accessible label is Edit cable line. The Edit cable menu shows the branch cables away from the protective device, in route order. When there is more than one cable or route segment, each cable is shown as Cable: {from} → {to}; each segment appears as Route segment {number} · {length}, or with “—” when its length is unknown. At the top, the Installation method for all route segments section applies the selected method to every segment in the branch; each individual segment can then be changed through its own installation-method option. As long as installation methods are missing or unconfirmed, the export tab shows a separate bulk-review section: Review cables step by step opens it, Choose an installation method is its selector; Fill empty intervals in selection fills empty fields only, and Confirm this cable’s installation methods confirms the entries cable by cable.

What the self-check verifies on installation methods, and what stays on site

The self-check verifies the rules that can be decided from the recorded project data. For the installation method that means, concretely:

Cross-section against protection: the self-check verifies that 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. Current-carrying capacity under the recorded method, grouping, ambient temperature and insulation belong to the design.
Fire class in hollow walls: for route segments with the installation method Behind wall panels, and for endpoints in rooms with hollow walls, a cable without a documented cable-wide conduit must reach at least characteristic F2 or class Cca (4.3.3.5 point b → 5.2.7.3). If the class is lower and no conduit is documented, PlanElec reports an error; if it is missing, a data gap. The Building cavity selection, the exceptions under 5.2.7.1 point 3 and 5.2.7.3 point 1 and the conduit rule in 5.2.7.4 are not yet part of the check.
Site dimensions: the installation zones of 5.2.9.10 point b, plaster or concrete cover and the depth of buried cables are not model data; the installer checks them on site.
Execution: whether the recorded method matches what was actually installed is a visual check on site. Measurements and the official assessment are carried out by the accredited inspection 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: in principle, only cables are admitted there, subject to the exceptions stated in those provisions.
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 F2/Cca — common in timber construction and suspended ceilings. PlanElec currently flags this only for Behind wall panels and for rooms with hollow walls, not for the Building cavity choice. Under the AREI, a conduit relieves the requirement only if it meets the conditions of 5.2.7.1 point 3 or 5.2.7.3 point 1 (4.3.3.5 point b → 5.2.7.3); conduits must also meet 5.2.7.4.
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.