6 - Protection against electric shock

Last edit: 25/03/2024

Chapter 6 of the Standard prescribes protection measures against electric shock

The Standard prescribes, in paragraph 6.2.2, the measures in order to reduce the risk of electric shock with live parts. In particular, the Standard says: 

Live parts shall be located inside enclosures that provide protection against contact with live parts of at least IP2X or IPXXB. 

The Standard outlines the following conditions for opening the enclosure, specifying when they must be adopted:
Casing that can be opened by means of a key or tool; In this case, the disconnector will be on the side of the enclosure, the switchboard must have an IP XXB or higher level of protection inside it in the areas that can be reached by the operator.
Casing that can be opened as a result of disconnection of live parts; The disconnector is present frontally, on the enclosure door. Since it can be manipulated only without voltage, there are no requirements for minimum safety levels; however, if a bypass system is present, which allows the door to be opened when voltage is present, the requirements of the previous point should be applied.
Casing that can be opened without the aid of a key or tool and without the disconnection of live parts. EVERY component of the enclosure must have IP XXB level of protection.

Section 6.3 lists the fail-safe protections designed to prevent the development of hazardous conditions in the event of failure of the insulation between the active parts and the grounds. Measures must be provided for each circuit or part of the equipment to prevent the occurrence of a contact voltage, or automatic disconnection of the power supply must be implemented before the duration of contact with a live part becomes a hazardous condition.

Measures to prevent the occurrence of a contact voltage include:
– Use of Class II equipment or equivalent insulation;
– Electrical separation.

The automatic interruption of a power supply to any circuit affected by an insulation fault is intended to prevent a dangerous situation arising from a contact voltage. This measure consists of the interruption of one or more line conductors by the automatic intervention of a protective device in the event of a fault. The interruption must occur in a short time to limit the duration of the contact voltage to a period within the limits specified in Annex A of the Standard for TN and TT systems.