Ex Norms

Introduction to the principles of explosion protected electrical equipment IEC 60079-0 to IEC 60079-18
Hazardous Area
For hazardous areas, it is very important that the product is designed for use in the actual area, and that operation and maintenance are according to the requirements.

The norms for hazardous areas are not the same for all over the world, but during the last years, the world wide harmonizing work have had much focus, and the IEC Ex certification is being ratified by more and more countries. For Europe, the ATEX directives for equipment (2014/34/EU) and worker protection (1999/92/EC) in potentially explosive atmospheres are mandatory.

This means that all products delivered for installation in hazardous area in buildings and fixed installations in Europe have to be certified according to the ATEX norms.

The ATEX directives are covering both electrical and non-electrical equipment, and for the first time, mechanical equipment falls under this type of legislation.

Classification of Zones
The hazardous areas have to be classified in Zones:

ZONE 0 is a place where an explosive atmosphere consisting of a mixture of air with any combination of flammable gas, vapour or mist is present continously, frequently or for long periods.

ZONE 1 is a place where an explosive atmosphere consisting of a mixture of air with any combination of flammable gas, vapour or mist is present only occasionally during normal operation.

ZONE 2 is a place where an explosive atmosphere consisting of a mixture of air with any combination of flammable gas, vapour or mist is not likely to occur in normal operation, but if it occurs, will persist for a short period of time.

For explosive atmospheres due to combustible dust in air, a similaire classification exists, with the zones numbered Zone 20, Zone 21 and Zone 22.

Category groups
Electrical equipment has to be classified in two different category groups:

Group I     Electrical equipment for mining
Group II    Electrical equipment for all remaining hazardous areas

Equipment group
For the different areas, the equipment has
to be classified

Group II. For gas and dust:
Zone 0/20    Equipment 1G/1D
Zone 1/21    Equipment 2G/2D
Zone 2/22    Equipment 3G/3D

Group I. For mining:
Methan    M1
Dust        M2 or M1


European Standard
European coding marking standard for products designed for use in hazardous areas:
    
Ex    is the coding for products confirming to IEC standard

EX
If the product confirms to the harmonised European Standards which has been notified by EU for the ATEX directive, the product will also carry the hexagon Exsymbol.


ex_varseltrekant
ZONE Marking
Directive 1999/92/EC do also have requirement that areas in which explosive atmospheres can occur must have warning signs.