Installation and operation of electrical equipment in hazardous locations

Duties of installer, manufacturer and employer

Safety in potentially explosive areas can only be guaranteed by a close and effective working relationship among all parties involved.

Cooperation of all parties involved Cooperation of all parties involved

The employer is responsible for the safety of his installations. It is his duty to verify where there is a risk of explosion and then divide areas into zones accordingly. He must ensure that the installation is installed in accordance with regulations and is inspected before initial use. The installation must be kept in a regular and correct state by periodic inspection and maintenance.

The installer must observe the installation requirements, and select and install the electric apparatus correctly for its intended use.

Manufacturers of explosion protected apparatus are responsible for routine testing, certification and documentation and are required to ensure that each device manufactured complies with the approved design.

Classification of zones and selection of apparatus

The question of possible risks of explosion must be addressed at the early stages new facility planning. When classifying potentially explosive areas, the influence of natural or technical ventilation must be considered in addition to the quantity of flammable substances being released. Furthermore, the explosion safety characteristics must be ascertained for the flammable substances being used.

Only then can a decision be reached on the classification of potentially explosive areas into zones and on a choice of suitable apparatus. IEC 60 079-14 (EN 60079-14) applies to the installation of electrical apparatus in explosive gas atmospheres group II. IEC 61241-14 (EN 61241-14) applies to all areas with combustible dust.

Equipment shall only be used within the ambient temperature range stipulated in its marking.

If the marking does not contain any information, the standard range of between –20 °C and +40 °C applies.

Electrical apparatus with the protection types “d” and “i” must correspond to an explosion group IIA, IIB or IIC. Electrical apparatus must be selected and installed such that it is protected against external influences which may adversely affect the explosion protection measures.


Periodic maintenance is required to maintain the safety of electrical installations in hazardous areas. Personnel who carry out such maintenance work should work under the guidance of an explosion protection expert and should be informed of the particular hazards involved (skilled person, IEC 60079-17).

Before corrective maintenance, it must be ensured that there is no danger of explosions occurring during this work. Normally, formal written permission for this should be acquired from the company management. On completion of the work, documentation should be kept of what work was carried out, and confirmation given that all relevant regulations have been observed.

In the event of changes that could affect explosion protection, an inspection is to be performed by a qualified person recognized by the responsible authorities. This is not necessary if the manufacturer of the device in question made the change.

When replacing components or entire apparatus, the explosion-prevention- and device-related characteristic data are to be observed. Only original parts from the manufacturer may be used. These inspections may also be performed by an approved inspection agency.