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02 April 2024

Designing and installing an electrical system: requirements and performance levels

Designing and installing an electrical system: requirements and performance levels

Nowadays, designing and installing a civil electrical system involves a series of obstacles and tricks resulting from an important technological evolution and renewed housing needs.

Suffice it to say that today’s legislative obligations require the introduction of renewable energy production systems (usually photovoltaic) for new buildings, and for important renovations, which therefore transform a “simple” consumer into a “prosumer”, able to interact with the national electricity grid, buying and selling energy.


What does all this mean for professionals?

First of all, the safety and compliance levels of the system must be increased: today, following the rule of the art and what the legislation imposes is not only an advice meant to impose a common standard, but it becomes a necessity to protect the installer in the event of failures or malfunctions potentially attributable to them.

This is why the regulatory system comes to the aid of professionals. 

As is known, the main document in the field of the design and installation of low voltage electrical systems is the IEC 64-8 standard which is about to be revised and published again with some updates already during 2024.

A condition that has become necessary above all to transpose the alignment and harmonisation documents to European Standards influenced by the technological evolution of recent years that has imposed the revision of many technical aspects, demanding new standards for plant engineering.


But what are the technical requirements to build an electrical system in the residential sector?

A real guide is provided by Chapter 37 of the Standard which specifically deals with the level of performance of the systems.

Within this section, in fact, 3 performance standards are defined, that first define the minimum levels required to consider the system in a workmanlike manner according to the CEI 64-8 Standard which, although not mandatory, supports and directs the work of the professional, limiting their responsibilities in the event of problems or failures.

Returning to the three performance levels, it is useful to verify how the first, the basic level, can in fact already be "off the market" today because, while guaranteeing safety and usability of the system, it is not in line with the traditional needs of the average user.

The suggestion, therefore, is to propose to its customer a system that has at least the characteristics of Level 2, which prescribes a series of additional functions, including consumption control in addition to the installation of additional devices for protection and safety.

Comfort, automation, energy savings and accessibility are instead typical of Level 3, a standard that looks to the future of plant engineering by providing features that enhance the system and the use of the equipment connected to it.

Chapter 37 does not stop there: inside, and specifically identifies precisely the Outlets, the light points and the radio/TV outlets that must be present in the housing unit, environment by environment, then providing an overview of the number of circuits, the auxiliary and accessory functions, as well as the arrangements for the digital infrastructure that must take into account first of all the size of the apartment and a correct risk assessment (in the case of protection against transient overvoltages).

We provide the in-depth links at the bottom of the article at each level, but we invite you to reflect on the Level 3 opportunity, defined as home automation, which offers a series of functions that, today, really represent an essential standard for any professional who wants to stand out on the market with a quality proposal.

By way of example, Level 3 could propose: video surveillance solutions, intrusion alarm, access control, detection and fire alarm (UNI 9795), anti-flooding and/or gas leak detection, lighting management with controls, shutter management, motorised curtains and covers, window management, doors, gates and motorised subledgers, multi-zone thermoregulation for winter heating and summer air conditioning, CMV management for air quality, programmable scenarios; irrigation management, sound diffusion, load control for anti-blackout and/or power limitation taken from the network, self-consumption load control for renewable energy efficiency, energy flow monitoring (production and consumption), recharging management of electric vehicles, electrical storage systems.

For completion, in addition to the provisions of the Tables above, it should be remembered that the latest version of the Standard indicates the sizing obligation for a power of at least 6 kW of the upright column of the system and the main switch, regardless of the type/size of the housing unit.

A requirement that aims to safeguard the electrification process of buildings that today often leads to the provision of totally "electric" houses without, therefore, alternative sources such as gas; the system will therefore have to cope with new consumption, first of all induction plates and electric heating systems such as heat pumps.

And it is also for this reason that the standard indicates, consequently, the adoption of a nominal diameter of the tubes of minimum 25 mm for uprights and ridges and 20 mm for terminal sections, with the attention to provide at least 30% of available space so as to be able to implement new circuits during the life of the system.

For the same reason, each residential unit must be equipped with one or more distribution panels (also in this case with the foresight to provide 30% of space available for new installations) and a general switch (automatic or manoeuvering) accessible to the user. In addition, the switch, if not automatic, must be adequately protected from overcurrents.

And if the main switch is differential, it must be selective with respect to the downstream differential switches or equipped with ARD (automatic closing device)

The IEC 64-8 also recommends the use of at least 2 independent circuits, but above all the use of type F differential for the protection of circuits that supply washing machines or air conditioners (or, more generally, inverter devices).

The eight parts of the Standard also contain a series of precise indications related to safety requirements, the choice and installation of electrical components, as well as checks and energy efficiency in the context of active user systems (prosumers); it is therefore necessary to be aware of these provisions to ensure that the rule of the art is complied with.

In support of the professional, however, during 2024, the new IEC Guide 64-53 "Guide for the integration of user electrical systems and for the preparation of auxiliary, telephone and data transmission systems in buildings - Particular criteria for mainly residential buildings" will be published.

A document that, through application examples and thanks above all to the new annexes, will provide precise instructions on the management of electronic signals and communication, anti-intrusion and video surveillance systems, the preparation for charging infrastructures of electric cars, as well as smart metering and HBES and BACS systems, introducing for the first time a focus on local energy production (photovoltaic) and management through the instrument of energy communities.

The document, which concluded its public inquiry process in January 2024, will soon be available to professionals and we will give you an accurate presentation over the next few months.


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