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06 February 2024

Previews on the CEI 64-8 standard new edition

Standard CEI 64-8: new edition coming soon

Over the next few weeks, CEI's Technical Committee 64 is scheduled to conclude its work on incorporating the comments to the public enquiry of the new edition of Standard CEI 64-8. The publication of the new document, which is widely regarded as the benchmark for the design, construction and operation of low-voltage installations, is therefore expected shortly.

Several changes have been made with respect to the previous editions, arising first and foremost from the Comitato Elettrotecnico Italiano's need to incorporate a number of harmonisation requests resulting from long-standing EU (CENELEC) obligations. However, the editorial structure of the document was revised on this occasion, updating the contents of the text and consolidating what was introduced into the normative body by the Variants published between the seventh and eighth editions of the Standard.


The main new features of the ninth edition of CEI 64-8

Awaiting the publication of the new edition of the Standard, which is expected - barring unforeseen events - by this summer, we will attempt to give a brief summary of the main changes in the new document. This is the premise that some specifications may be subject to further changes following the comments from the public enquiry.

New definitions for protection against direct and indirect contacts

First of all, the document introduces new terms such as “basic protection” and “fault protection”, replacing the previous definitions of protection against direct and indirect contacts (main protection and fault protection).

Protection against overcurrents

The text updates and modifies the general rule for the coordination of protections in TN systems in the event of automatic circuit interruption. Basically, until now it was permitted to protect a socket circuit with a protection greater than 32 A with an intervention within 5 seconds, with the new edition of the Standard this will no longer be possible. Protections will have to trip within 0.4 seconds (0.2 in special environments).

Ground fault protection downstream of inverter

In TN systems downstream of an inverter, the general rule for the coordination of circuit breakers “does not apply”, as the inverter is an active component limiting the fault current. The new edition of the standard takes this into account and stipulates that, in the event of a fault, the voltage downstream of the inverter must be reduced to values that are not dangerous to people (i.e. 50 VAC and 120 VDC).

Main equipotential bonding

New clarifications with regard to main equipotential bonding inside buildings. It will be possible to avoid connecting conduits entering the building with insulating joints to the main node.

Differential circuit breakers

The obligation to install 30 mA differential circuit breakers in residential areas is extended. Not only for circuits supplying plug sockets with a rated current of less than 20 A, but also for light circuits.

Class II

New developments are expected with regard to “double insulation”. With the transposition of document HD 60364-4-41, the nominal voltage limit of up to 690 VAC or 1035 VDC will be eliminated, benefiting the installation of photovoltaic systems and charging stations for electric vehicles.

Protection against indirect contacts in IT systems

In DC systems, no limitation is taken into account for the contact voltage, as the value of Id can be considered negligibly low. It will therefore be possible to ignore the first-fault current.

Isolation and Switching

The transposition of document HD 60364-4-46 - Isolation and switching, introduces three significant changes, the first concerns the rules for neutral conductor isolation in TN systems, the second concerns functional switching, and the third concerns stored electrical energy.

Constructions sites

In the new wording of Chapter 704, the indication of 25 ohms for the purpose of coordination with protections disappears.

Further Amendments to Part 7

The final text of the standard will then draw attention to a number of specific areas, with a focus on camping areas, docks, fairs, exhibitions, photovoltaic systems, furniture elements, caravans, electric vehicles, power supply for inland waterway vessels and environments with a higher fire risk.


CEI 64-8: the evolution from 1984 to today

The reason for so much attention around the new edition of the CEI 64-8 standard is easy to understand. This document is in fact a fundamental pillar in the Italian regulatory landscape regarding electrical installations.

Its evolutionary path, which started with the first publication in 1984, has been marked by major changes over the years, adapting to the changing technological and regulatory requirements of the sector.

In the context of the 1980s, the electrical industry was facing a series of challenges related to the introduction of new technologies and the need to define clear guidelines to ensure the safety and efficiency of electrical installations. The Comitato Elettrotecnico Italiano responded to this need by launching standard CEI 64-8, which was proposed as a unified tool for the design and installation of electrical systems.

However, within a few years, with the need to adapt to technological evolution and new industrial requirements, the standard underwent its first revisions, also influenced by alignment with renewed European and international standards, especially in the field of safety.

With the arrival of the new millennium, in light of an ever-increasing focus on sustainability and energy efficiency issues, CEI 64-8 had to adapt to these renewed requirements while also focusing on the digitalisation of systems and buildings, without considering the unprecedented relationship and the increasingly close links with the distribution network. This was called into question with the introduction of the concepts of active users and prosumers, as well as the introduction of new complexities created by the integration of photovoltaic systems, energy storage systems and charging stations for electric vehicles.

Therefore, while we await the publication of the new regulatory document, please follow us so that we can promptly provide you with the main changes and new features that will impact the work of installers and planners.