Zones and Categories

A hazardous areas is classified into Zones (0, 1 or 2 for gasses and vapors, 20, 21 or 22 for dust).

 

According to the directive equipment is divided into 2 groups, which are sub-divided into categories. The categories correspond with a certain Zone where it may be used.

 

Zones
     

ATEX Marking 

CE xxxx Ex  + (below)

Industry Protection Zone Equipment
group
Category
of protection
Gas/Dust
Mines Equipment remains functional
with explosive atmospheres
I M1
Equipment to be de-energized in the
event of an explosive atmosphere
I M2
Surface Very high 0

20

II 1 G

D

High 1

21

II 2 G

D

Normal 2

22

II 3 G

D

 

Example: II 1 G/D means the apparatus is not certified for use in mines and suitable for Zone 0 (gas) and Zone 20 (dust).

NEC500/505

In the US the National Electric code is in force. The NEC500 divides a hazardous area into Division, with Division I approximately matching Zone 0 and Zone 1 together. Division 2 approximately matches Zone 2. 

 

Classification
  Flamable Material
Present Continuously
Flamable Material
Present Intermittently
Flamable Material
Present Abnormally
IEC / CENELEC Zone 0

(Zone 20 dust)

Zone 1

(Zone 21 dust)

Zone 2

(Zone 22 dust)

NEC505 Zone 0 Zone 1 Zone 2
NEC500

Division 1

Division 2

IEC classification per  IEC 60079-10

CENELEC classification per EN 60079-10

US classification per ANSI/NFPA NEC article 500 of article 505

 

Suitable types of protection are often "Explosion Proof" (~ Ex d) and Intrinsic Safety (~Ex ia). There are no equivalents of Ex m and Ex e under this code.

De NEC505 divides the hazardous area in to Zones as does ATEX, and allows virtually identical types of protection.