Zones and Categories
ATEX
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
|
|||||||
| 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 |
|||
xxxx 
+ (below)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
NEC500
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.
NEC505
De NEC505 divides the hazardous area in to Zones as does ATEX, and allows virtually identical types of protection.