Installations

Electrical earthing installations

The electrical earthing installation is the system of protection against indirect contacts through automatic interruption of the supply.

An ISPESL circular defines inspection of the earthing installation as “the inspection of the system of protection against indirect contacts with automatic interruption of the supply, in the meaning of the state of the art under Law 186/68, in particular of standards CEI 64-8, CEI 11-1 and the corresponding IEC standards and European harmonisation documents”.

CEI Guide 0-14 defines an earthing installation as the set of earth electrodes, earthing conductors, equipotential conductors, main earthing terminals and protective conductors intended to provide protective earthing. It also intends that, for the purposes of the decree, first-fault indicators (where they exist) and devices for protection against overcurrents or leakage currents provided to ensure protection against indirect contacts form part of the earthing installation.

Electrical installations whose protection against indirect contacts is based on a different method (e.g. double insulation or electrical separation) are not subject to the inspection obligation under art. 4(1) of D.P.R. 462/01, nor are earthing installations made for purposes other than protection against indirect contacts (e.g. cathodic protection, earthing of SPDs, etc.).

Devices for protection against atmospheric discharges

Installations and devices for protection against atmospheric discharges relating to structures that are not self-protected are subject to the inspection obligation under art. 4(1) of D.P.R. 462/01.

Under art. 84 of Legislative Decree 81/08, according to which “Il datore di lavoro provvede affinché gli edifici, gli impianti, le strutture, le attrezzature, siano protetti dagli effetti dei fulmini con sistemi di protezione realizzati secondo le norme di buona tecnica”, all protection installations relating to structures that according to CEI 81/10 are “not self-protected” must be inspected.

Where structures are self-protected according to the applicable CEI standard and lightning protection installations and/or devices are consequently not installed, the employer must keep the technical report on the lightning risk assessment and produce it on request of the supervisory authorities.

Inspection of the lightning protection installation means inspection of the system of protection against direct and indirect lightning strikes.

Electrical installations in places with an explosion hazard

Before Legislative Decree 233/03, identification of “places with an explosion hazard” referred to Tables A and B of Ministerial Decree 22/12/58 (to which arts. 329 and 331 of D.P.R. 547/55 applied).

With the entry into force of Legislative Decree 233/03 the identification of places with an explosion hazard for the application of D.P.R. 462/01 changed. Classification is no longer conventional and table-based: reference must be made to an actual classification of hazardous places.

According to Legislative Decree 233/03:

• The employer must notify ASL/ARPA of electrical installations in areas classified as zone 0 and zone 1 in the presence of gas, and electrical installations in areas classified as zone 20 and zone 21 in the presence of dust;
• The employer ensures that electrical installations in areas classified as zones 0, 1, 20 or 21 undergo the biennial inspections required by D.P.R. 462/01.
• In installations whose classification results only in zones 2 or 22, notification is not required (without prejudice to the obligation to carry out regular checks and maintenance).

However, where notification and periodic inspection are required (zones 0-1-20-21), that inspection must cover the entire installation of the place with an explosion hazard and therefore also that relating to zones 2 and 22 (clarification in CEI Guide 0-14). This inspection must include, in addition to the electrical installation, the suitability of any hazardous machines at the place of installation.

For the classification of hazardous zones, reference is made to CEI 31-30 for explosive atmospheres in the presence of gas and to CEI 31-52 for explosive atmospheres in the presence of combustible dust.

CLASSIFICATION OF AREAS WITH AN EXPLOSION RISK

Zone 0 Area in which an explosive atmosphere consisting of a mixture of air and flammable substances in the form of gas, vapour or mist is present continuously or for long periods or frequently.

Zone 1 Area in which the formation of an explosive atmosphere consisting of a mixture of air and flammable substances in the form of gas, vapours or mist is likely to occur occasionally during normal activities.

Zone 2 Area in which during normal activities the formation of an explosive atmosphere consisting of a mixture of air and flammable substances in the form of gas, vapour or mist is not likely or, if it occurs, is of short duration only.

Zone 20 Area in which an explosive atmosphere in the form of a cloud of combustible dust in air is present continuously or for long periods or frequently.

Zone 21 Area in which the formation of an explosive atmosphere in the form of a cloud of combustible dust in air is likely to occur occasionally during normal activities.

Zone 22 Area in which during normal activities the formation of an explosive atmosphere in the form of a cloud of combustible dust is not likely or, if it occurs, is of short duration only.

“Normal activities” means the situation in which installations are used within their design parameters.

For the classification of areas or places, reference may be made to the harmonised technical standards relating to the specific sectors, including:

• CEI 31-30 “Classificazione dei luoghi pericolosi” and subsequent amendments.
• CEI 31-66 “Classificazione delle aree dove sono o possono essere presenti polveri combustibili” and subsequent amendments.

and the related guides CEI 31-35 and CEI 31-56.