The first time you see a single-line diagram, it looks like a tangle of lines, letters and numbers. Yet it
follows a fixed logic: from the meter to the distribution board, and from there circuit by circuit to every
light point and every socket. In ten short lessons you learn to draw up a single-line diagram yourself using
that logic. No prior knowledge is needed. Together we draw one house in 1wire, from the first circuit to the
plan for the inspection.
Follow them in order: each lesson adds a piece to the same example house. After lesson 10 you have a complete
single-line diagram and floor plan. For the example house, allow about two hours; tracing the circuits of an
existing house can take much longer. Open the
free drawing sheet
in a second window and draw along. You don't need to create an account.
After this lesson you know which two plans you draw up, what goes on them and how a
diagram is built.
In Belgium, an electrical installation is described by two drawings that belong together. Together they
form the plan that the inspector lays next to the installation during the inspection, and that then stays
in the electrical file of the house. The plan must show the installation as it was actually
built.
The single-line diagram shows how everything is connected: which protective
device feeds which circuit, which cable runs there and which switches, lamps and sockets are on it. It says
nothing about the location in the house.
The floor plan (situatieplan) shows where everything is: a plan of each
floor with the same symbols on it.
The name “single-line” comes from the most important convention: one line represents the whole
cable, even though in reality three, four or five conductors run side by side. How many there
are and how thick they are is written in a code next to the line.
How a diagram is built
You draw the diagram from the supply to the loads. The supply comes in at the bottom: the grid operator's
connection with the electricity meter. Next comes the distribution board, a long
horizontal line. From that line the circuits run upwards, each with its own capital
letter. You build each circuit from the bottom up: first the protective device, then the cable, then the
switches and loads.
Below is what we are working towards: the complete diagram of the example house, a house with a ground
floor and a first floor. In the next lessons you draw it yourself, piece by piece.
The end result of this series of lessons, drawn in 1wire. Click to enlarge.
kWh
The supply: meter, 300 mA main switch and earthing. You draw it in lesson 3.
A–B
Two circuits directly on the board: the hob and the
oven. That is lesson 4.
C
A 30 mA RCD with its own rail: the lighting (D, E) and the sockets (F). That is
lesson 5.
G
A second 30 mA RCD: washing machine, dryer, dishwasher and bathroom (H to K).
Drawing an existing house? The example house follows the rules for a new installation, as
they have been in the AREI since 1 June 2023. Your installation may look different, especially if it is
older. That is not a problem: you always draw what is actually there. Lesson 5 shows what an
older installation often looks like.
open your drawing sheet
Open a new drawing
sheet. 1wire opens on the Single-line diagram tab.
On the left is the symbol library, Add components, grouped by type. On the right
is the drawing sheet.
The floor plan has its own tab, Floor plan. You will get there in lesson 9.
If you work without an account, 1wire keeps your drawing temporarily in your browser. With a free account,
everything is saved online automatically.
After this lesson you know which circuits you draw: for a new house you divide it into
circuits, for an existing house you trace the circuits. That is the work that comes before drawing.
A circuit is everything behind one circuit breaker (often simply called a “fuse”): the
cable, the switches, the lamps and the sockets. If you start drawing straight away, you often have to
rearrange things afterwards. So first find out which circuits there are. How you do that depends on the
house.
Dividing a new house into circuits
Go through the house room by room and list what will be there: light points with their switches, sockets and
fixed appliances. Then divide them into circuits according to these rules:
Sockets: at most eight sockets per circuit. A double or triple socket counts as
one.
Lighting: in a home with more than two rooms, compulsorily spread over at least two
circuits, so the whole house doesn't go dark when one breaker trips. A split per floor is simple and
clear.
Heavy fixed appliances: the hob, the oven, the washing machine, the dryer and the
dishwasher each get their own circuit, as does any other fixed appliance of 2600 W or
more.
Behind 30 mA: the bathroom, the washing machine, the dryer and the dishwasher, and
since 1 June 2023 also the lighting and ordinary sockets. At most eight circuits per 30 mA RCD. Fixed
appliances such as the hob and the oven may go directly behind the 300 mA (lesson 5).
An existing house: tracing the circuits
In an existing house, the division is already fixed. You trace it, starting from the distribution board:
Record the board. Write down every RCD and every circuit breaker (or fuse) in the
order they sit in the board, with what is printed on them. Lessons 4 and 5 explain where to find that. An
existing label next to the breakers is a useful start, but check it.
Switch off one breaker and walk through the house: which lamps no longer work, which
sockets have no power? A small lamp or a socket tester makes this quick. Note everything per room.
Switch it back on and repeat for the next breaker. That way each breaker gets its list
of points: that is one circuit.
Do the same with each RCD, to see which breakers sit behind it.
Only operate the switches in the board; don't open the board, any box or any socket. What you cannot see,
such as the cross-section of a cable buried in the wall, ask an electrician.
How the example house is divided
This is how our example house, a new installation, is divided. 1wire assigns the letters A to K itself,
according to the position of each circuit on the board.
and
are the two 30 mA RCDs: they get a letter too.
Circuit
Purpose
What is on it
Behind
Hob
the hob in the kitchen
300 mA
Oven
the oven in the kitchen
300 mA
Lighting ground floor
living room (2 lamps, 1 switch), stair light (switch at the bottom and the top)
30 mA (C)
Lighting first floor
bedroom (3 switching points), landing
30 mA (C)
Sockets
5 socket groups in the living room, 2 of them double
30 mA (C)
–
Washing machine, dryer, dishwasher
each appliance its own circuit
30 mA (G)
Bathroom
lamp with waterproof switch, socket
30 mA (G)
Tip: a real house usually has more socket circuits, for example for the kitchen and the
bedrooms. We keep the example house deliberately small, so that each element appears only once.
the circuits and their names
In 1wire your division shows up in the Circuits tab: a list of all circuits with
their letter, their number of points and their name. You fill in the names as you draw (lesson 6), and can
look them up there at any time.
After this lesson the start of every diagram is on your drawing sheet: meter, main
switch, distribution board and earthing.
The supply sits at the bottom of every diagram. It consists of four parts:
The electricity meter, a small rectangle with “kWh”. It measures how much energy the
house uses and belongs to the grid operator.
The main switch, in a home usually a 300 mA RCD (differential
switch). It switches off the whole installation in one go. On the device itself this value is often
given in amperes: IΔn 0.3 A is the same as 300 mA.
The distribution board: the horizontal line from which all circuits will start.
The earthing, bottom left under the board. The two small cross strokes are the
earth disconnect link, which lets the inspector disconnect the earth to measure it. The
three ever shorter lines are the earth electrode in the ground.
The supply of the example house.This is what a 300 mA main switch looks like: “40 A / IΔn 0,3 A”.
Which supply do you draw?
The type of connection determines how many conductors come in, and so usually also how many poles the main
switch has. You write that on the diagram as 2P, 3P or
4P. The table gives the usual cases. When you draw an existing installation, copy what is
on the main switch itself: sometimes, for example, there is a four-pole device on a three-phase supply
without neutral, connected according to the manufacturer's diagram.
Supply
Supply conductors
Usually
Where you find it
230 V single-phase
1 phase + neutral
2P
Most homes, like the example house.
230 V single-phase on a 3 × 230 V network
2 phases, no neutral
2P
Older networks, in part of the country.
3 × 230 V
3 phases, no neutral
3P
Three-phase on those same older networks.
3 × 400 V + N
3 phases + neutral
4P
New builds and homes with heavy loads such as a heat pump or a charging point.
Careful with blue: a 3 × 230 V network has no neutral. There, the blue conductor can also be
a phase and be live.
Why the earthing belongs on the plan
All metal enclosures and the green-yellow protective conductors are connected to the earth. If a live
conductor touches a metal cabinet somewhere, the current flows away to earth instead of through whoever
touches the cabinet. That is why the inspector measures the earth resistance of the earth
electrode. The AREI aims for at most 30 Ω and never allows 100 Ω or more in a home. Between 30 and 100 Ω,
stricter rules apply to the RCDs (lesson 5).
the supply is already there
A new project starts with a meter, a 300 mA main switch, a distribution board and earthing. You don't
have to draw them yourself.
Click the main switch and set Number of poles to the number of poles of the
device: usually 2 for a single-phase supply and 4 for 3 × 400 V + N.
If you work with an account, also set the current type in the Project details
tab. It appears at the bottom of every printed page.
After this lesson you choose the right circuit breaker for each circuit and draw the
first circuits on the board.
Each circuit starts on the board with its own protective device. It protects the cable
against too much current, because a conductor that has to carry too much current heats up and can start a
fire. Too much current arises in two ways:
Overload: too many appliances run on the same circuit at once. Think of an iron, a
kettle and a fan heater on the same extension lead.
Short circuit: the phase touches the neutral or another phase directly, for example
when someone drives a nail through a cable in the wall.
A circuit breaker or a fuse protects against this: both then switch the circuit off.
Circuit breaker or fuse?
In everyday speech they are used as synonyms. Many people say “the fuse has blown”, even when the board has a
circuit breaker. Technically they are two different devices:
A fuse contains a thin wire that melts when the current is too high, after which you
have to replace it. You still find them in older homes.
A circuit breaker switches off by itself, and once the cause is fixed you simply switch
it back on. New installations almost always have circuit breakers.
Both protect the cable against overload and short circuit, but they are not interchangeable at the same
rating: on 2.5 mm² a circuit breaker may go up to 20 A, a fuse only up to 16 A (see the table below). If an
older home has fuses, you draw fuses, because the plan shows what is actually there.
The label
Next to each circuit breaker you write its characteristics. For
(sockets) of the example house that is
2P - C 20A with a box 3000:
2Ptwo poles: both conductors (phase and neutral) are switched
Cthe tripping curve; C is the usual choice in homes
20Athe rated current: how much may flow through the circuit
continuously; above that the breaker trips, faster the higher the current
3000the breaking capacity in amperes: the largest short-circuit current
it can safely interrupt
Where to find this on the breaker itself
The same data is on the front of every circuit breaker in the board, usually just below the brand. So you
can fill in the diagram simply by looking in the distribution board:
C20 (or “C 20”): curve C and the rated current of 20 A.
3000 in a box: the breaking capacity in amperes. Copy it into the box on the
diagram.
The number of poles is usually not written on it. The number of terminal screws at the
top is a first clue: two on a two-pole, four on a four-pole breaker. Also look at the marking and the small
wiring diagram on the device. That way you can tell a 2P from a 1P+N:
the latter also has two terminals, but only protects the phase. An N next to a terminal
shows where the neutral goes.
The manufacturer's type code (such as VYC32), the voltage (400V~) and the small digit under the box (the
energy limiting class) don't need to go on the diagram.
Two-pole (2P): two screws, C20 and 3000.Four-pole (4P): four screws, the last pole marked N.
Thicker cable, bigger breaker
Which breaker you choose depends on the cross-section of the cable behind it. A thin
conductor can carry less current, so it needs a smaller protective device. The table gives the
upper limit per cross-section in a home (AREI, table 4.11); a bigger breaker is never
allowed. Whether a combination is really suitable also depends on the load, the installation method and the
length of the cable (voltage drop). The electrician works that out. For the same cross-section, the limit
for a fuse is lower than for a circuit breaker.
Cross-section
Max. circuit breaker
Max. fuse
In the example house
1.5 mm²
16 A
10 A
Lighting and
: 16 A
2.5 mm²
20 A
16 A
Sockets, oven and appliances: 20 A
4 mm²
25 A
20 A
—
6 mm²
40 A
32 A
Single-phase hob : 32 A
10 mm²
63 A
50 A
Supply to a board or a large load
the first circuits on the board
In the group Cables, circuit breakers and RCDs, click
Circuit breaker with cable. Insert mode switches on.
Blue insertion points appear on the drawing sheet. Click the distribution board to add
the circuit. Draw the hob and the oven this way, the two circuits that go directly on the main board.
Press Escape to stop. The circuits behind the 30 mA follow in lesson 5.
Click a circuit breaker and fill in Number of poles,
Current, Curve and
Short-circuit current in the panel on the left. The label next to the symbol
updates immediately.
Is there a fuse in the board? Then choose Fuse instead of
Circuit breaker under Type.
In insert mode, blue circles show where the symbol can go.The panel of the breaker of circuit F. Each field becomes part of the label; the breaking
capacity is called Short-circuit current here.
After this lesson you know which circuits go behind a 30 mA RCD, what changed about that
in 2023, and you draw each RCD with its own rail.
An RCD (residual current device, also called a differential switch) compares the current
that leaves through the phase with the current that comes back through the neutral. If current leaks away
somewhere, for example to earth through a faulty washing machine or through someone touching a conductor,
less comes back. That difference is the leakage current. If it gets too large, the RCD
trips within a fraction of a second.
The 300 mA main switch from lesson 3 protects the whole house, mainly against fire
caused by leakage currents.
An additional 30 mA RCD is much more sensitive and protects people against electric
shock.
Which circuits behind 30 mA? The rules since 1 June 2023
On 1 June 2023 the AREI rules for homes became stricter. For a new installation the rules are now, if the
earth resistance is at most 30 Ω:
Behind a 30 mA RCD: the bathroom, the washing machine, the
dryer and the dishwasher, and now also the lighting and
the sockets that are not intended for a fixed appliance.
At most eight circuits behind each 30 mA RCD.
Fixed appliances such as the hob, the oven, a fridge or electric heating may go directly behind the
300 mA.
If the earth resistance is between 30 and 100 Ω, there must be at least two 30 mA RCDs, each with at
most sixteen sockets; a fixed appliance counts as a socket. The other circuits then go behind an RCD of at
most 100 mA. We don't go further into that special case here.
The diagram shows the type and characteristics of each RCD. In a home, type A is the
minimum, and the RCD at the origin of the installation is rated at least 40 A.
The example house follows these rules.
protects the lighting and the sockets (,
and ),
the washing machine, the dryer, the dishwasher
and the bathroom (H to K). A single RCD for all seven circuits would also be allowed, but with two, a leakage
current only cuts off part of the house. In a larger house, the lighting is often spread over both RCDs, so
that the lamps never all go out at once.
On the diagram, each RCD sits on the main board, with its own rail behind it. All circuits
on that rail are protected by the 30 mA. Each circuit still keeps its own circuit breaker: the RCD watches
for leakage current, the breaker for overload and short circuit.
The two 30 mA RCDs, each with its own rail: C for lighting and sockets, G for laundry and
bathroom.
The label
For both RCDs of the example house you write Type A - Δ30mA, 3000 and
2P - 40A. Don't mix up two numbers:
40A is the current the device may carry continuously. An RCD does not protect itself
against overload; so don't choose it smaller than the protection of the supply, 40 A in the example
house.
Δ30mA is the leakage current at which it trips. On the device it is often given in
amperes: IΔn 0,03 A is 30 mA, IΔn 0,3 A is 300 mA. On the diagram you
write milliamperes.
Type A also detects leakage currents from electronic appliances. It is compulsory in
homes; the older type AC has no longer been allowed since 2023, not even in existing installations.
What it says on the RCD itself
Look in the distribution board and you will find everything you need for the diagram on the front of the
RCD:
40 A: the current the device may carry.
IΔn 0,03 A or IΔn 0,3 A: the leakage current, in amperes. Convert to
milliamperes: 0.03 A = 30 mA and 0.3 A = 300 mA.
A with a small wave in a box: the type, here type A.
T: the test button. Press it as often as the manufacturer says; the RCD must then
trip.
The number of poles: count the terminals at the top, just as on a circuit breaker. Two
terminals (phase and N) is 2P, four is 4P.
30 mA: “40 A / IΔn 0,03 A”, type A.300 mA: “40 A / IΔn 0,3 A”, type A.
What an older installation often looks like
Many homes were wired before June 2023. There, the lighting and the sockets often sit directly behind the
300 mA, and there is only one 30 mA RCD, for the bathroom and the laundry. The 2023 rules apply first and
foremost to new installations. For existing installations and for minor changes or extensions to existing
circuits, the AREI provides exemptions and transitional rules. Some new rules do apply to everyone, such as
the ban on type AC. Whether your installation is in order is for the inspector to judge.
Parts installed before 1 October 1981 are marked “old installation” (“oude installatie”) on
the single-line diagram.
If you draw an existing house, draw what is actually there, even if it looks like the
example below. Never adjust the plan to the rules: the inspector compares the plan with the installation.
A layout you often see in older homes: lighting and sockets (A to C) directly behind the 300 mA,
and a single 30 mA RCD (F) for the laundry and the bathroom.
the RCDs and their rails
In Cables, circuit breakers and RCDs, choose the
Type A 2-pole differential switch and click the main board.
Add a Distribution board behind it: that is the rail for the circuits behind the
30 mA. With Circuit breaker with distribution board you place both in one go.
On that rail, draw the circuits for the lighting and the sockets, each with a
Circuit breaker with cable.
Repeat for the second RCD, with the circuits for the washing machine, dryer, dishwasher and
bathroom.
Check Residual current (30 mA), RCD type (A) and
Current in the panel.
1wire also gives the branches with the RCDs themselves a letter,
and ,
so you can refer to them by name. Their name stays empty.
The settings of RCD C.
Lesson 6
6
Cables and circuit names
After this lesson you write the right code next to every cable and give every circuit a
name.
Above each circuit breaker, the cable runs to the points of the circuit. On the diagram that is one line
with a code next to it. For of the example
house it is VOB Eca 3G2,5:
VOBthe type: single insulated wires, pulled through a conduit
Ecathe fire class of the cable: how it behaves in a fire
3the number of conductors
Git includes a green-yellow protective conductor
2,5the cross-section of each conductor in mm² (with a decimal
comma)
Besides VOB you will often come across XVB: a cable with a sturdy outer sheath that may also
be laid on or in a wall without conduit. Underground it goes in a conduit; where and how a cable may be laid
is in the manufacturer's data sheet. Choose the cross-section to match the breaker from lesson 4: 1.5 mm²
for lighting, 2.5 mm² for sockets and most appliances. The small marks on the line show how the cable is
installed. In 1wire the two E marks mean “built into the wall” and the small circle “in
conduit”.
Junction and connection boxes also belong on the diagram. In 1wire you find them in the
Branch points group.
Labels: letter plus number
Within a circuit, each point gets a sequence number. That creates a label such as
: circuit F, point 3. That label later also appears
on the floor plan, and that is how the two plans are linked. Also give each circuit a clear
name, such as “Lighting first floor”. That helps the inspector, and later the occupant when
something fails.
The colours of the conductors
You don't draw colours on the diagram, but you need to know them to compare the diagram with the
installation:
Conductor
Colour
Function
Protective conductor (PE)
green-yellow
connects metal parts to earth; never use it for anything else
Neutral (N)
blue
the return path of the current
Phase (L)
brown, black or grey
the conductor that is live
Don't rely on colour alone. Older installations still have other colours, and on a 3 × 230 V
network a blue conductor can also be a phase (lesson 3).
filling in the cable and naming the circuit
Click the line above a circuit breaker. In the Wire panel, choose
Cable type, Fire class,
Number of conductors, Placement and
Cross-section, and tick Protective conductor. 1wire writes
the code next to the line itself.
At the bottom of the panel, under Circuit, fill in the
Circuit name.
1wire assigns the letters and sequence numbers automatically. With
Circuit names and Sub-circuit names at the top of the
drawing sheet you show or hide the names.
After this lesson you choose the right switch for one, two or three switching points and
draw the lighting circuits.
A light point is a small cross. A switch is a small circle with a slanted
arm. The shape of that arm tells you which kind of switch it is. Which one you choose depends on
from how many places the light must be switched:
Switch
Symbol
When do you choose it?
Single-pole
One lamp or group of lamps, switched from one place. The switch only breaks the phase.
Double-pole
Breaks both phase and neutral. A good choice in damp rooms such as the bathroom.
Two-way switch
Always in pairs: switching one lamp from two places, such as the top and bottom of
a staircase.
Intermediate switch
Between two two-way switches, for three or more places. Each extra place is one more
intermediate switch.
Rule of thumb: in a classic circuit with two or more switching points, the first and the last
switch are two-way switches. Everything in between is an intermediate switch. Four places therefore gives
two-way – intermediate – intermediate – two-way.
Many switching points? Then people often choose push buttons with an
impulse relay in the board: each press of a button turns the light on or off, however many
buttons there are. In 1wire you find them in the Switches, push buttons and relays
group.
The lighting of the example house
, living room: two lamps that are always on
together, with one single-pole switch. You draw one cross with “x2”.
, stairs: a two-way switch downstairs and one
upstairs, with one lamp.
, bedroom: switches at the door and on both
sides of the bed, so two-way – intermediate – two-way.
, landing: a single-pole switch.
Each lamp with its switches is one point on the circuit. Two lamps you want to switch separately become two
points.
This is what it looks like once circuits D and E are drawn.
switch and lamp in one go
Open the Light points, spotlights and LEDs group with the arrow next to the number
of variants.
Choose the combination that fits the point: Switch + light,
2-pole switch + light, 2x Switch + light (two two-way
switches) or 3x Switch + light (two-way, intermediate, two-way).
Click an insertion point on the cable. For two lamps on one switch, set the quantity of the light point
to 2.
Need to change a switch later? Click it and tick Two-way switch or
Intermediate switch, or set Number of poles to 2.
The variants of Light points, spotlights and LEDs.The middle switch of E1 is an intermediate switch.
After this lesson you draw sockets and fixed appliances, and choose the cable for a
hob.
A socket is a half arc with a short stroke: the stroke is the earth. A double socket gets
two arcs side by side, a triple three. On
you draw five socket groups: single at points 1, 2 and 4, double at points 3 and 5.
Sockets in a home must have child protection: shutters that close off the holes. On the
diagram you see this from the short strokes at both ends of the arc.
Fixed appliances are small squares with their own sign inside.
is the hob (four cooking zones),
the oven. Each appliance gets its own
circuit breaker and cable.
A small “h” next to a symbol means it is waterproof. You use it in the bathroom: for the
lamp, the switch and the socket of . That
letter alone does not make equipment suitable for every spot: in a bathroom, the zones around the bath and
shower determine which equipment is allowed where and what degree of protection (IP) it needs.
is a mixed circuit:
lighting and a socket together. Because there is a socket on it, the rules for a socket circuit apply to
the whole circuit: at least 2.5 mm² and at most eight points. A light point, or a group of lamps with one
common switch, counts as one socket.
Circuit F: sockets.Circuit A (hob) and B (oven).
The hob: the appliance determines the connection
A hob needs a lot of power. In the example house, with a single-phase supply, we choose a
3G6 cable with a 32 A circuit breaker. On a three-phase supply, a hob can
spread its power over two or three phases; that needs more conductors, but a smaller cross-section is often
enough. How a hob is connected is in the wiring diagram of the appliance itself; the
electrician chooses the cable and breaker accordingly. On the diagram you copy what is actually there.
Charging point, solar panels and heat pump
New heavy loads also each get their own circuit with their own circuit breaker. A charging
point needs an RCD that also detects DC leakage: a type B, or a type A together with 6 mA DC
detection, which many charging points already have built in. Follow the charging point's manual for this.
Solar panels connect through the inverter to their own circuit. In 1wire, the charging point
and the heat pump are under Devices, the inverters under Solar
panels and batteries. For a home battery with backup power there is a separate guide:
drawing a backup power circuit.
adding sockets and appliances
In the Sockets group, choose a Socket,
2 sockets or 3 sockets and click the cable of the circuit.
Every socket you add gets its own sequence number.
Child protection is on by default in the panel; leave it on in a home. Tick
Waterproof where needed.
The oven, washing machine, dryer and dishwasher are in the Devices group; the hob
is called Cooker there.
Everything you draw automatically ends up in the Material list. Handy for checking
that you haven't forgotten anything.
After this lesson you draw the plan of each floor and put every point from the diagram
in the right place.
The floor plan is a plan of each floor with the symbols from the diagram. Below each symbol is its
label. That label is the bridge between the two plans:
on the diagram is exactly the same socket as F3 on
the floor plan.
You draw up the floor plan in three steps:
The plan. Draw the walls, doors and stairs of each floor. It doesn't have to be an
architect's drawing: the rooms must be recognisable and the proportions right.
The points. Put every light point, switch, socket and appliance where it actually
is.
The distribution board. Also show where the board is.
The ground floor of the example house: each symbol carries the label from the single-line
diagram.
One label, several places
Sometimes more than one symbol carries the same label. Everything with the same label belongs to the same
point. Take , the stair lighting: you put the lamp
and one two-way switch downstairs in the hall, the second two-way switch upstairs on the landing. So the
first floor also has a D2, even though it is on the ground-floor lighting circuit. In the bedroom you place
three times: at the door and on both sides of the
bed.
The first floor: three switches E1 in the bedroom and the second switch of D2 at the top of the
stairs.
drawing the plan and placing the points
Open the Floor plan tab. Rename the first floor and add another with
New floor.
Draw the walls with Straight wall, and add doors, windows and the stairs with
Door, Window and Interior. Use
Board to mark the distribution board and Text for the room
names. If you already have a plan as an image or PDF, you can import it with
Image.
On the left, under Place components, are all points from your diagram, per
circuit. Click a symbol and then the plan to place it. The R key rotates it.
Filter on Unplaced to see what is still missing.
Feel free to work with both plans side by side: in the single-line diagram, click
Floor plan at the top right. Select a symbol on one side and it lights up on the
other side too.
After this lesson you check your plan with a checklist and print it as a PDF.
Before you hand the plan to the inspector, go through it once from start to finish. This checklist follows
the same order as the lessons:
The supply
Meter, main switch with type, poles, current and Δ300mA, distribution board, earth disconnect link and
earthing. The voltage and type of current, for example 230 V AC.
Every circuit
A letter, a clear name and a circuit breaker with poles, curve and current that match the cable.
The RCDs
For each RCD the type, the leakage current and the current. New installation: lighting, sockets,
bathroom and laundry behind 30 mA, at most eight circuits per RCD.
Every cable
Type, fire class, number of conductors and cross-section, for example VOB Eca 3G2,5. No line without a
code.
Every point
The right symbol for every switch, lamp, socket and appliance. At most eight sockets per circuit, with
child protection. The junction and connection boxes too.
The floor plan
Every floor, the distribution board and every point with its label. Nothing left under “Unplaced”.
The plan matches the house
A plan that is neatly drawn but doesn't match what is in the walls helps nobody. So compare the diagram with
the distribution board itself: every breaker on the board belongs on the diagram, with the same value. That
also applies to an older installation that doesn't meet the 2023 rules: the plan shows the installation as it
is. If something changes in the installation later, update the plan too.
checking and making the PDF
Check the circuits in the Circuits tab and the material in the
Material list.
The Not placed on floor plan button in the single-line diagram shows how many
points are not yet on the plan.
In the Project details tab, fill in the installation address, the EAN code, the
electrician and the inspection body. They appear at the bottom of every page. That tab appears as soon as
you work with an account.
Open the print screen with the printer icon at the top. Choose A4 or A3, tick the parts and click
Export PDF. If the diagram doesn't fit on one sheet, 1wire spreads it over several
pages; a dotted line on the drawing sheet shows where a page ends.
The print screen: choose what goes into the PDF.
Drawing in 1wire is free. You only pay when you want to print the plan without restrictions.
A good plan really proves its worth when something goes wrong. If breaker
trips in the example house, the diagram tells you
that E is the lighting of the first floor, with points
(bedroom) and
(landing). On the floor plan you see straight away
where they are. If trips, the washing machine,
the dryer, the dishwasher and the bathroom all go off at once. That often points to a leakage current in one
of those appliances. Unplug them, switch G back on and plug them in again one by one: if G trips again, you
know which appliance an electrician should take a look at.
Please note: these lessons teach you to draw up a single-line diagram and floor plan that
correctly represent an installation. The choices in the example house follow common rules for homes. For a
real installation the AREI remains the standard, and the inspector checks whether the plan and the
installation match. Leave work on the installation itself to an electrician.
Sources (in Dutch): the AREI, Book 1 (low-voltage installations), 2026 edition, published by the
FPS Economy, and
Volta's overview of the changes of 1 June 2023. Last checked: October 2026.
Get started
Draw up your first single-line diagram
Start with the supply, add the circuits one by one and then put everything on the floor plan. Free, in
your browser, nothing to install.
What is the difference between a single-line diagram and a floor plan?
The single-line diagram shows how everything is connected electrically: protective devices, cables,
switches and loads. The floor plan shows where those parts are in the house. Together they form the plan of
the installation; labels such as F3 link them to each other.
Why is it called a “single-line” diagram?
Because one line represents the whole cable, even though it contains several conductors. The number of
conductors and their cross-section are given in a code next to the line, for example 3G2,5.
When do you need a single-line diagram?
At every inspection: before a new installation is put into use, when a house is sold and after a major
extension or modification. The inspector lays the single-line diagram and the floor plan next to the
installation. Afterwards they belong in the electrical file of the house.
I'm drawing an existing house. Does my diagram have to look like the one in the lessons?
No. The example house follows the rules for a new installation from after June 2023. An existing
installation often looks different, for example with the lighting and sockets directly behind the 300 mA.
You always draw what is actually there. Lesson 5 shows what such an older
installation looks like.
Do I have to date and sign the plan?
Not as the owner: since 1 June 2023 the owner no longer has to date and sign the single-line diagrams and
floor plans. If the installation passes the inspection, the person responsible for carrying out the work
and the approved inspection body do sign and date them. Each plan also carries a number, a version and the
date of that version. For a new installation or a major modification, the name and capacity (and VAT
number) of whoever did the work also appear on the plans, as does the address of the installation.
How long does it take to draw up a single-line diagram?
The drawing itself is quick: for an ordinary house with about ten circuits, once you know the lessons,
allow a few hours for the diagram and the floor plan. 1wire numbers the circuits and points itself and
keeps both plans linked. In an existing house, tracing the circuits often takes longer than the drawing,
especially if nothing is labelled on the board.
I'm studying electrical engineering. Can I use 1wire for free to practise?
Yes. You can start drawing in the browser right away, without an account. For students and teachers there
is also a free student account. Diagrams from a student account cannot
be used as an official AREI plan, though.
I only have an old plan on paper. Do I have to start from scratch?
No. With 1wire you can scan a photo or PDF of an existing
single-line diagram. It is converted into an editable diagram that you can check and complete with these
lessons.
Where can I find a symbol that isn't in these lessons?
After these lessons, may I work on my installation myself?
These lessons teach you to draw up the plan, not to build or change the installation. Work on the
installation must comply with the AREI and is checked at the inspection. Leave that work to an
electrician.
