Ultima modifica: 09/01/2024
6.2.3.1 Accesso al Quadro
Questo è il capitolo che è stato più modificato rispetto all’edizione del 2018.
Ecco l’estratto dell’edizione 2018:
[NFPA 79: 2018] 6.2.3.1 Enclosure Interlocking.
When required by 5.3.1.4, each disconnecting means mounted within or adjacent to a control enclosure that contains live parts operating at 50 volts ac (rms value) or 60 volts dc or more shall be mechanically or
electrically interlocked, or both, with the control enclosure doors so that none of the doors open unless the power is disconnected. Interlocking shall be reactivated automatically when all the doors are closed.
Ecco il nuovo estratto:
[NFPA 79: 2021] 6.2.3.1 Enclosure Access.
Opening an enclosure (e.g. doors, lid, cover) that contains live parts operating at or above 50 volts rms ac or 60 volts dc shall be permitted only under one or more of the following conditions:
- The use of a key or tool is necessary for access to live parts operating at or above 50 volts rms ac or 60 volts dc. AII live parts mounted on the inside of doors or covers that are operating at or above 50 volts rms ac or 60 volts dc shall be protected from unintentional direct contact by the inherent design of components or the application of barriers or obstacles such that a 50 mm (2 in.) sphere cannot contact any live parts. A safety sign shall be provided in accordance with 16.2.4.
- The disconnecting means supplying the enclosure is interlocked with the enclosure door(s) in accordance with 6.2.3.2.
- Opening without the use of a key or a tool and without disconnection of live parts shall be permitted only when all live parts inside that are operating at or above 50 volts rms ac or 60 volts dc are separately enclosed or guarded such that there cannot be any contact with live parts. A safety sign shall be provided in accordance with 16.2.4.
In sostanza, l’interno di un quadro industriale d’automazione non richiede alcun tipo di protezione dai contatti diretti (IP 0 nella terminologia IEC). Se il livello IP 1 è garantito per i componenti montati all’interno delle porte del quadro, allora è sufficiente una chiave per garantire la protezione; in caso contrario, tutte le porte devono essere interbloccate.
Ciò significa che, dal 2021, non sarà più necessario alcun interblocco delle porte per la maggior parte dei quadri di automazione con destinazione USA o Canada.