2. Electrical safety system

2.4. CLASSIFICATION OF PREMISES ON THE DEGREE OF HAZARD OF PEACEFUL HAZARDS WITH ELECTRIC SHOCK

PUE (6 th ed.) In Sec. 1.1.13 determine the following classes of rooms in relation to the risk of electric shock to people:

1. Premises without increased danger, in which there are no conditions that create an increased or special danger.
2. Premises with increased danger, characterized by the presence in them of one of the following conditions, creating an increased danger:
   1. Dampness (humidity more than 75%) or conductive dust;
   2. Conductive floors (metal, earth, reinforced concrete, brick, etc.);

   3. High temperature (above 35 ° C);

   4. The possibility of a simultaneous touch of a person to the metal structures of buildings, connected to the ground, technological devices, mechanisms, etc., on the one hand, and to the metal cases of electrical equipment, on the other.
3. Particularly dangerous premises, characterized by the presence of one of the following conditions, creating a special danger:
   1. Special dampness;
   2. A chemically active or organic medium;
   3. Simultaneously two or more conditions of increased danger.
4. Territory of external electrical installation. With regard to the risk of electric shock to people, these territories are equated with especially dangerous premises.

In Table. 2.3 Limit values ​​of voltages are given, at excess of which protection against indirect contact is required depending on the category of the room.

Table 2.3.

Room category	PUE (6th edition), paragraph 1.7.33	The draft of the new edition of the PUE
Without increased danger	> = 380 VAC. Current	> 50V AC Current
	> = 440 VDC. Current	> 120 VDC. Current
With increased danger, especially dangerous and external electrical installations	> 42 V AC Current	> 25 V AC Current
	> 110 VDC. Current	> 60 VDC. Current

From the table it follows that in the new edition of the code, the requirements for providing electrical safety conditions are much higher.

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