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This page offers a growing amount of valuable information aiming to help you efficiently preparing and designing your electrical wiring diagrams. Have a suggestion or a good tip? Don’t hesitate to share it on the forum.


Drawing quick tips

The Scalable Vector Graphics format: drawing completely free with open source software

You don't have a license for Visio or AutoCAD and you don't want to use trial software? Then the SVG-format will come to your rescue. Simply download one of the many free drawing software packages supporting the SVG-format and you are ready to go. The GPL licensed open source software Inkscape for example bundles all features you'll ever need... completely free.

SVG AREI-symbolen in Inkscape
Recommended zoom levels for Visio

The Visio AREI-shapes are natively designed to work at a zoom level of 400%. Because the shapes are freely scalable, each zoom level can of course be used. It is considered good practice to pick shapes from the document stencil should you consistently use custom scaled shapes.

Guides in Visio

Even though all Visio AREI-shapes feature connection- and glue points aligning different symbols might, depending on your Visio settings be challenging: e.g. light switch has a complete different goniometry compared to a circuit breaker. To overcome this challenge you might want to use guides, simply click and drag a guide from the horizontal or vertical ruler. Another useful setting is to let Visio snap to connection points only.

Guides in Visio
Multiple light fixtures controlled by the same switch

A few drawing simplifications are worth mentioning to keep the wiring diagram uncluttered. Multiple light fixtures controlled by the same switch can be drawn with a single lighting shape but with a textual indication of the exact amount of fixtures. For example x2 or x8 for respectively 2 or 8 light fixtures.

The above mentioned drawing method does not apply to the floor plan. This plan must show the exact location of each individual light fixture. Single light fixtures containing multiple light sources, e.g. a chandelier are drawn as single lighting shape.

Multiple light fixtures controlled by the same switch
Multiple socket outlets covered by the same face plate

It is also not required to draw all individual socket outlets covered by the same face plate on the wiring diagram. Instead a single socket outlet shape is used with a textual indication of the exact amount. For example x2 or x5 for respectively 2 or 5 socket outlets. This way of drawing is also allowed on the floor plan.

Multiple socket outlets covered by the same face plate
Appliances on the wiring diagram

Appliances with a fixed location and connected with a power cord such as a dish washer or a tumble dryer are drawn next to the socket outlet on the wiring diagram. Appliances connected via a wire are drawn next to their junction box or connection point. It is also allowed to use a reference to the appliance should drawing space be limited.

Appliances on the wiring diagram

Photovoltaic installations

Photovoltaic installations are subjected to the AREI legislation.

Despite the variations in photovoltaic installations the drawing should contain at least following elements for installations limited to ≤10 kVA:

  1. The inverter (DC/AC converter)
  2. The green power meter
  3. The protection devices like RCBO and circuit breakers
  4. Cable specifications
  5. The AREI does not provide official symbols for solar panels or inverters

Drawing example:

Photovoltaic installations on the wiriging diagram

Power demands of household appliances

Below a listing of some commonly used household appliances and their approximate power demand. The actual power demand of your appliances may vary substantially from these figures. Bear in mind that most devices will not constantly consume this amount of energy. Be sure to check the owner's manual for the correct figures.

Device Watts
Refrigerator Freezer Combo A+ 150W - 200W
Refrigerator Freezer Combo C 200W - 350W
Dishwasher 1.200W
Deep fryer 2.000W
Stove 4 heating zones 7.100W
Stove 2 heating zones 3.500W
Electric range 5.900W - 11.000W
Electric oven 2.000W - 2.500W
Microwave oven 1.000W - 1.500W
Steamer 2.200W - 3.600W
Coffee machine 500W - 1.000W
Extractor hood 70W - 150W
Electric boiler 5L 2.000W
Electric boiler 50L 2.200W
Electric boiler 100L 2.200W - 4.000W
Electric boiler 200L 4.500W
Tankless water heater 12.000W - 21.000W
Device Watts
Tumble dryer C 2500W - 3000W
Washing machine A+++ 2500W - 3000W
Iron 750W - 1100W
Hoover 650W - 1200W
Freezer A++ 120W - 350W
Device Watts
Electric shaver 8W - 12W
Portable heater 1000W - 2000W
Hair dryer 300W - 1200W
Flat iron 20W - 100W
Curling iron 200W - 1200W
Hair curler set 300W - 450W
Living room
Device Watts
LCD CCFL TV 90W - 250W
LCD LED TV 20W - 140W
Setop box 12W - 20W
Video game console 20W - 180W
Hifi micro system 35W-120W
AV-receiver 150W-450W
Device Watts
Computer with LCD monitor 350W - 800W
Laptop 250W - 360W
Laser printer 250W - 1100W
Inkjet printer 180W - 480W

Power requirements per socket outlet

When designing a domestic electrical installation on paper it is fair to say that not all socket outlets will already have a designate purpose. Nevertheless it is considered to be good practice to take your future power requirements into consideration. The table below contains average guiding power demands per socket outlet for some common rooms.

Room Average guiding power demand
Living room 100W
Kitchen 150W
Stairway and landing 100W
Bathroom 100W
Bedroom 100W - 120W
Garage 100W
The provided values are averages and do not represent continuous power demands. Some socket outlets will be used only sporadically others might not be used at all. The average power demand per outlet will decrease when the amount of outlets increases.

Phase load balancing

A phase load balancing table is not a mandatory document but is for sure the best method to get the loads in a polyphased electrical installation distributed evenly.

This example describes a typical domestic electrical installation: 3-phase star connected with neutral. The goal is to distribute the loads among phases so that the cumulated demand deviates less than 10% from each other.

Below an example of a well-balanced electrical installation:

Circuit L1,N L2,N L3,N L1,L2,L3,N
A 360W
B 670W
C 150W
D 280W
E 720W
F 840W
G 750W
H 2600W
I 600W
J 2950W
K 440W
L 1300W
M 3000W
N 10000W
O 4500W
TOTAL 4970W 4780W 4910W 14500w
  • Total demand: 29160 W
  • Maximal demand for line 1: 9803W or 42.62A at 230V L1,N + (L1,L2,L3,N/3)
  • Maximal demand for line 2: 9613W or 41.79A at 230V L2,N + (L1,L2,L3,N/3)
  • Maximal demand for line 3: 9743W or 42.36A at 230V L3,N + (L1,L2,L3,N/3)

The common neutral current in a perfectly balanced star connection is 0A. The common neutral current will increase as the demand between phases becomes more asymmetrical.

  • The common neutral current at full load for this example will only be 0.74A.

Note that the above calculation uses a maximal load, which in real life will never happen.

Calculate it yourself

Below you can calculate the estimated common neutral current by inputting the current for each line. Please note that this simplified formula does not take the power factor into account:

Current line 1: A at 0°
Current line 2: A at 120°
Current line 3: A at 240°
0A at an angle of 0°
ATTENTION: The common neutral is the single conductor connecting the distribution board to the power meter not to be confused with the individual neutral wire of each smaller circuit!
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