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.

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.

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 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.

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.

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:

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.

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.

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:

• 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.

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: