Section 7. Electrical equipment of special installations

Electrical installations in fire hazardous areas. Electrical apparatus and devices

Encyclopedia of radio electronics and electrical engineering / Rules for the installation of electrical installations (PUE)

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7.4.20. In fire hazardous areas, electrical devices, instruments, cabinets and terminal assemblies can be used that have a degree of shell protection in accordance with GOST 14255-69* that is not less than that indicated in table. 7.4.2.

It is allowed to change the degree of protection of the shell from water penetration (2nd digit of the designation) depending on the environmental conditions in which the devices and instruments are installed.

Table 7.4.2. Minimum permissible degrees of protection for the shells of electrical devices, instruments, cabinets and terminal assemblies, depending on the class of fire hazardous zone

* When installing devices and devices that spark due to operating conditions. Until the electrical industry adopts cabinets with an IP54 enclosure protection degree, cabinets with an IP44 enclosure protection degree can be used.

** When installing devices and devices in them that do not spark due to working conditions.

7.4.21. Devices and devices installed in cabinets may have a lower degree of enclosure protection than indicated in the table. 7.4.2 (including version IP00), provided that the cabinets have a degree of shell protection not lower than that specified in table. 7.4.2 for this fire hazardous area.

7.4.22. In fire hazardous areas of any class, apparatus, instruments, cabinets and clamp assemblies can be used, purged with clean air under excess pressure.

7.4.23. In fire hazardous areas of any class, oil-filled devices and devices can be used (with the exception of oxygen installations and lifting mechanisms, where the use of these devices and devices is prohibited).

7.4.24. It is recommended to remove panels and switches for lighting networks from fire hazardous areas of any class, unless this causes a significant increase in the cost and consumption of non-ferrous metals.

Electrical installations of locked warehouses, which contain fire hazardous areas of any class, must have devices for disconnecting power and lighting networks from the outside, regardless of the presence of disconnect devices inside the premises. Switching devices must be installed in a box made of fireproof material with a device for sealing on an enclosing structure made of fireproof material, and in its absence - on a separate support.

Switching devices must be available for maintenance at any time of the day.

7.4.25. If electric heating devices are required in fire hazardous areas of any class due to production conditions, then their heated working parts must be protected from contact with flammable substances, and the devices themselves must be installed on a surface made of non-combustible material. To protect electric heating devices from thermal radiation, it is necessary to install screens made of fireproof materials.

In fire hazardous areas of any class of warehouse premises, as well as in buildings of archives, museums, galleries, libraries (except for specially designed premises, such as canteens), the use of electric heating devices is prohibited.

See other articles Section Rules for the installation of electrical installations (PUE).

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