Guide to CEI terms and schemes for electrical systems

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• What is CEI?
• How do CEI Schemes work?

Electrical systems are a very important tool for the safety and efficiency of the electrical system. The technical regulation of electrical systems and the structures in which they are established is governed by the regulations developed by the Italian Electrotechnical Committee (CEI), which determine the creation of schemes, standards and requirements for plant engineering. This guide will refer to the terms and verification methods listed in the main CEI schemes, to provide readers with an overview of electrical engineering and facilitate their understanding.

What is CEI?

The Italian Electrotechnical Committee (CEI) is a technical body that decides standards, regulations and requirements for electrical plant engineering. The CEI is responsible for the formulation of diagrams pursuant to the law on electrical systems (Ministerial Decree 37/08) and their compliance with the national legislation in force.

How do CEI Schemes work?

The CEI standards define the standards with which electrical systems and structures must be designed to ensure their safety and functionality. These are quality and safety requirements, for example: compliance with well-defined procedures and design rules; the regulation of tools, devices and services; the selection of compatible components. The various CEI schemes also establish methods of verification and control to verify the conformity of the systems.

Scheme 1 - Direct current premise

The first Scheme of the CEI establishes the formation of a direct current system. The DC premise describes how the electrical system will need to be designed to supply the proper voltage and handle the proper current flow. It also establishes the correct countermeasure in cases of voltage and functionality problems.

Scheme 2 - Design Specifications

The second scheme of the CEI establishes the design specifications of both industrial and domestic systems. It intends to ensure the proper functioning of the system, the thermal and safety parameters. Furthermore, it establishes the minimum criteria for carrying out correct and safe installations and requires the adoption of adequate protection devices.

• Observe measurement standards and voltage limits
• Use approved electrified devices
• Be able to ensure a safe installation and execution process
• Comply with the specially defined certification criteria

Scheme 3 - Security Checks

The third scheme of the CEI establishes the security checks, which must be carried out once the designed systems have been segregated. Checking the operation of the scheme involves checking the voltage, current, electroluminescence, degree of protection and noise levels. Furthermore, a continuous measurement of the polarization, of the proper power cycle and the situation of the conductors and connectors must be checked.

• Check voltage
• Check current
• Check the electroluminescence
• Check the degree of protection
• Measuring noise levels
• Check polarization
• Check power cycling
• Check leads and connectors