An electrical diagram, what is it for, why is it essential?


In the context of a construction or a renovation, the electrical installation is one of the longest and most complex finishing works. In order not to tangle the brushes during the works, it is strongly recommended to draw up an electrical diagram from the start to know all the details of the installation and its components.

What is an electrical diagram?

Presented in the form of a diagram or a plan, the electrical diagram is made up of a series of universal symbols which accurately describe the installation. The NFC 15-100 electrical standard now requires the creation of this type of architectural plan which must be duplicated and given to the user. It consists of a number of crucial data including complete information on the safety systems, the intensity of the setting current, the electricity consumed by the various equipment, the layout of the cables, the number and location of the cables. different outputs, etc.

The creation of this electrical diagram is strongly recommended because it offers all the explanations and data on the equipment to be installed. In the case of a construction, this plan will help define the budget necessary for the installation. Later, during maintenance or repair, the interested party will only have to refer to this document to carry out the work more easily. In principle, there are four types of electrical plans:

  • Among the most common is the developed electrical diagram which is appreciated for the simplicity of the symbols used and the location of the devices. This plan has the advantage of avoiding crossings of wires.
  • Then comes the architectural scheme which offers a plan view of the house in which the various devices and appliances are located. In principle, this diagram is the work of a project manager or an architect.
  • Using the same symbols as the architectural diagram, the third single-line diagram represents a plan of the housing incorporating the various electrical conduits housing the conductors.
  • Last and not least: the multi-line diagram generally used by professionals shows the routing of the wiring as well as the conductors. Very precise, this diagram also displays the number and the nature of the wires.

In which case is the diagram essential?

Drawing up an electrical diagram is recommended in the context of the installation of a lighting system operating by switch control. Taking into account the electrical plan of the house as well as the color codes is important for the installation. This begins with the junction box through which we take the red phase wire pointing to the switch and ensuring the cut. The bulb socket will be connected to the neutral blue wire. The red phase wire adopts a new color (black, brown or gray) as soon as it passes through the switch. The ideal is to choose a switch with indicator light when the latter is not in the room to be able to control the lighting and prevent the latter from turning on when you are no longer in the room.

This same system can be used for two-way wiring. The neutral wires will therefore point towards the switch and the phase wire towards the switch. Ditto, it is possible to use the technique to extinguish a light point via two points. On the other hand, if there are more than two switches, it will be necessary to use a toggle switch.

When installing a dimmer, it is also advisable to draw up an electrical diagram. Allowing to modulate the lighting in several rooms of the house, this system requires a connection almost identical to that used with the switches. One of the two-way control buttons can be replaced by a dimmer. However, the wiring must be done properly.

The main families of electrical symbols to know to read an electrical plan

There are essentially five main families of electrical symbols that you need to know well in order to be able to decode an electrical diagram.

Among the most important are electrical control symbols representing in particular switches, pushbuttons, dimmers or key control systems.

Come next the symbols representing the lights including fluorescent strips, ceiling lights, spotlights or projectors.

Third, we find socket symbols, antenna or network and then those like specialized circuits or equipment to name only the refrigerator, the hobs, the air conditioner or the heating.

There is also the electrical symbols of the equipment and specialized circuits such as the refrigerator, hood, washing machine or dishwasher …

Finally, there is various symbols representing for example a loudspeaker, a bell, an antenna or a toggle switch.

Although simple at first glance, the creation of an electrical diagram requires the knowledge of a specialist. Its interpretation will become simpler and the work will be done more safely and quickly.