Guide to Hazardous Locations
Explosive Dust Atmospheres
Ex Marking
Protection
Concepts
Type of Protection
Code
Market
US (NEC 500) and CA (CEC Section 18)
®
Type of protection
(not used in CA)
Ex
Ex
Ex
CA
EU
IEC
(DIP)
US
CA
US
CA
US
IEC
US
CA
EU
IEC
US
CA
EU
IEC
US
CA
EU
IEC
US
CA
US
CA
EU
IEC
US
IEC
US
CA
EU
IEC
US
IEC
US
CA
EU
IEC
US
CA
US
CA
US
CA
US
EU
IEC
US
CA
US
CA
EU
IEC
US
EU
IEC
US
CA
EU
IEC
US
EU
IEC
EU
IEC
US
CA
Permitted Class
Dust-Ignitionproof for Class II,
Division 1, Groups E, F, G T5
Permitted Division
(optional except for Division 2)
Permitted Class
AEx
US
CA
US
CA
US
General Requirements
Temperature Class
(T5 and T6 optional)
Dust-Ignitionproof
Permitted Group
Dust-Protected
Ambient temperature ranges other than standard (-25°C ≤ Ta ≤ +40°C)
must be marked.
Protection by Enclosure AEx tD
Ex tD
AEx ta
Ex ta
Ex ta
Ex ta
AEx tb
Ex tb
Ex tb
Ex tb
AEx tc
Ex tc
Ex tc
Ex tc
Fiber + Flying Protection (DIP)
US (NEC® 506 per 61241)
American National Standard
Temperature Classification
Zone 21 AEx tD T120°C
Permitted Zone
Type of Protection
Ambient temperature ranges other than standard (-20°C ≤ Ta ≤ +40°C)
must be marked.
US (NEC® 506 per 60079)
American National Standard
Temperature Class
Zone 21, AEx tb IIIC T120°C
Permitted Zone
Encapsulation
Equipment Group
Type of Protection
Ambient temperature ranges other than standard (-20°C ≤ Ta ≤ +40°C)
must be marked.
IEC (61241)
Test Protocol & Intended Zone
of Installation (only used for tD)
Max Surface Temperature
Ex tD A21 T120°C IP66
Type of Protection
Explosion Protected
Ingress Protection
Ambient temperature ranges other than standard (-20°C ≤ Ta ≤ +40°C)
must be marked.
Pressurization
EU and IEC (per 60079)
Equipment Group Temperature Class
Ex tb IIIC T120°C Db
Type of Protection
Equipment Protection Level
Intrinsic Safety
Ambient temperature ranges other than standard (-20°C ≤ Ta ≤ +40°C)
must be marked.
EU (Directive 94/9/EC) ATEX
CE Conformity Marking
Explosion Protection Marking
Category (including “D” for dusts)
1725
II 2 D
.
Equipment Group
Identification Number of Notified Body
Involved in Production Control Stage
EPL/Category
Definition
Dust atmospheres,
“very high” level of
protection
(NI)
AEx ma
Ex ma
Ex ma
Ex ma
AEx maD
Ex maD
AEx mb
Ex mb
Ex mb
Ex mb
AEx mbD
Ex mbD
AEx mc
Ex mc
Ex mc
Ex mc
(PX)
(PX)
(PY)
(PY)
(PZ)
(PZ)
AEx pD
Ex pD
Ex pD
(I.S.)
(I.S.)
AEx ia
Ex ia
Ex ia
Ex ia
AEx iaD
Ex iaD
Ex iaD
AEx ib
Ex ib
Ex ib
Ex ib
AEx ibD
Ex ibD
Ex ibD
Ex ic
Ex ic
(I.S.)
(I.S.)
Application
Class II, Division 1 & 2
Class II, Division 1 & 2
Class III, Division 1 & 2
Class III, Division 1 & 2
Zone 20, 21, & 22
Class II/III
Category 1D, 2D, & 3D
Zone 20, 21, 22
EPL Da, Db, & Dc
Class II, Division 1
Class II, Division 1
Class II, Division 2
Class II, Division 2
Zone 21
EPL Db
Zone 20
Class II/III, Division 1+
Category 1D
EPL Da
Zone 21
Class II/III, Division 1+
Category 2D
EPL Db
Zone 22
Class II/III, Division 2+
Category 3D
EPL Dc
Class III, Division 1 & 2
Class III, Division 1 & 2
Zone 20
Class II/III, Division 1+
Category 1D
EPL Da
Zone 20
EPL Da
Zone 21
Class II/III, Division 1+
Category 2D
EPL Db
Zone 21
EPL Db
Zone 21
Class II/III, Division 2+
Category 2D
EPL Dc
Class II, Division 1
Class II, Division 1
Class II, Division 1
Class II, Division 1
Class II, Division 2
Class II, Division 2
Zone 21
Category 2D
EPL Db
Class II, Division 1
Class II, Division 1
Zone 20
Class II/III, Division 1+
Category 1D
EPL Da
Zone 20
Category 1D
EPL Da
Zone 21
Class II/III, Division 1+
Category 2D
EPL Db
Zone 21
Category 2D
EPL Db
Category 3D
EPL Dc
Class III, Division 1
Class III, Division 1
Standard
FM 3600
CSA C22.2 No. 0
FM 3600
CSA C22.2 No. 0
ISA 61241-0 or
ISA 60079-0
CSA C22.2 No. 60079-0
EN 60079-0
IEC 61241-0 or
IEC 60079-0
FM 3616
CSA C22.2 No. 25
FM 3611
CSA C22.2 No. 25
ISA 61241-1
IEC 61241-1
ISA 60079-31
CSA C22.2 No. 60079-31
EN 60079-31
IEC 60079-31
ISA 60079-31
CSA C22.2 No. 60079-31
EN 60079-31
IEC 60079-31
ISA 60079-31
CSA C22.2 No. 60079-31
EN 60079-31
IEC 60079-31
FM 3611
CSA C22.1
ISA 61241-18
CSA C22.2 No. 60079-18
EN 60079-18
IEC 60079-18
ISA 61241-18
IEC 61241-18
ISA 60079-18
CSA C22.2 No. 60079-18
EN 60079-18
IEC 60079-18
ISA 61241-18
IEC 61241-18
ISA 60079-18
CSA C22.2 No. 60079-18
EN 60079-18
IEC 60079-18
FM 3620 (NFPA 496)
NFPA 496
FM 3620 (NFPA 496)
NFPA 496
FM 3620 (NFPA 496)
NFPA 496
ISA 61241-2
EN 61241-4
IEC 61241-4
FM 3610
CSA C22.2 No. 157
ISA 60079-11
CSA C22.2 No. 60079-11
EN 60079-11
IEC 60079-11
ISA 61241-11
EN 61241-11
IEC 61241-11
ISA 60079-11
CSA C22.2 No. 60079-11
EN 60079-11
IEC 0079-11
ISA 61241-11
EN 61241-11
IEC 61241-11
EN 60079-11
IEC 60079-11
FM 3610
CSA C22.2 No. 157
Protection Principle
Equipment Grouping
EU (60079) US (NEC 506
Typical material
Metal dusts
Carbonaceous dusts
Non-conductive dusts
Fibers and flyings
Dust atmospheres,
“enhanced” level of
protection
Dc
III
2D
II
3D
21
Keep
combustible
dust out
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N/A
D
Class II, Group E
IIIB
D
D
Class II, Group F
IIIB
D
D
Class II, Group G
IIIA
D
D
Class III
IIIC
US NEC 500
Class II or III
450°C
300°C
280°C
260°C
230°C
215°C
200°C
180°C
165°C
160°C
135°C
120°C
100°C
85°C
No temperture
marking
For Class II, the temperature
class is determined with a
maximum dust layer* on the
equipment.
For installation, that temperature class must not be greater
than the dust layer or dust cloud
ignition temperature.
For organic dusts that may
dehydrate or carbonize, temperature classes greater than
“T3B” (165°C) are not permitted.
Not Recognized
For Class III, the temperature
is determined with a maximum
dust layer* on the equipment.
The temperature must not be
greater 120°C for equipment
that can be overloaded and
165°C for equipment not subject
to overloading.
For Class II or III, the temperature is determined with a
maximum dust layer* on the
equipment.
The temperature must not be
greater 120°C for equipment
that can be overloaded and
165°C for equipment not
subject to overloading.
Marking
US NEC 506
EU/IEC
Temperature is determined
with no dust layer on the
equipment.
Temperature is determined
For installations with layers
with a maximum dust layer*
up to 5mm thick, that temon the equipment.
perature must be at least 75K
below the dust layer ignition
For installation, that temperatemperature and no more 2/3
ture must not be greater than the
of the dust cloud ignition
dust layer or dust cloud ignition
temperature. For installations
temperature.
with layers up to 50mm thick,
IEC/EN 61241-14 provides
information on reduction of
temperature.
T___°C
Temperature class
in degrees Celsius
preceded by a “T” e.g. T120°C
Limit
energy of
sparks and
surface
temperature
CA CEC Sect 18
Class II or III
TL ___°C
Temperature class
in degrees Celsius
preceded by a “TL”
with a dust layer of
“L” where “L” is the
layer depth in mm e.g. T500120°C
Temperature is determined
with specified layer depth,
(> 50 mm) on all sides of the
equipment. That temperature
must be at least 75K below the
dust layer ignition temperature
and no more 2/3 of the dust
cloud ignition temperature.
Not recognized
* A maximum dust layer is a layer or blanket of wheat flour, corn flour, or grain dust that results
from the equipment being covered with dust until no more will stay on the equipment.
Ingress Protection (IP) Codes
First characteristic Numeral
Second characteristic Numeral
Protection against solid bodies
Protection against liquid
0
1
2
No protection
No protection
Objects greater than 50mm
Vertical (90˚) dripping water
Objects greater than 12mm
70˚ to 90˚ dripping water
3
4
5
6
7
8
Objects greater than 2.5mm
Sprayed water
Objects greater than 1mm
Splashed water
Dust-protected
Water jets
Dust-tight
Heavy seas
Effects of immersion
Indefinite immersion
+
The Canadian Electrical Code (through 2012) does not recognize Zone 20, 21, or 22. Therefore, in addition to the Type of Protection
Code, the Class, Division and Group of the application is also marked.
Approximate U.S. enclosure type equivalent to IPXX
Type
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Market
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T1
T2
T2A
T2B
T2C
T2D
T3
T3A
T3B
T3C
T4
T4A
T5
T6
22
Level of protection assigned to equipment based on its likelihood of becoming a
source of ignition
US (NEC 500)
CA (CEC Section 18)
per 61241)
Marking
Da
Db
IEC (61241)
IEC (60079)
US (NEC 506
per 60079)
Temperature
Note 2: For associated intrinsically safe apparatus not suitable for installation in a hazardous location, both the symbol “Ex” or “AEx”
and the symbol for the type of protection “iaD” “ibD”, “ia”, or “ib” are enclosed within the same square brackets, e.g. [AEx iaD] or
[AEx ia] IIIC; in this case, a temperature class is not included.
Dust atmospheres,
“high” level of
protection
Combustible Dust
Present
Abnormally
Zone 22
Zone 22
Division 2
Division 2
61241 did not differentiate between different materials, but referred to all with a “D” suffix on the Type of Protection.
Note 1: For associated intrinsically safe apparatus suitable for installation in a hazardous location, the symbol for the type of
protection “iaD”, “ibD”, “ia”, or “ib” are enclosed within square brackets, e.g. AEx tb [ia] IIIC T135 °C or AEx tD [iaD] T135°C.
20
Combustible
Dust Present
Dust Present
Continuously
Intermittently
Zone 20
Zone 21
IEC / EU
Zone 20
Zone 21
US NEC 500
US NEC 506
Division 1
Division 1
CA CEC Section 18
US area classification per ANSI/NFPA 70 National Electrical Code® (NEC®) Article 500 or Article 506
CA area classification per CSA C22.1 Canadian Electrical Code (CEC) Section 18
EU area classification per EN 60079-10-2 or EN 61241-10
IEC area classification per IEC 60079-10-2 or IEC 61241-10
Typical Zone
IEC
EU (ATEX)
of
Application
EPL Group Category Group
1D
Area Classification
Combustible
US
Canada
C
C
C
US
US
EU (ATEX)
FM Approvals can also issue IECEx Test Reports, Quality Assessment Reports and Certificates of Conformity.
IP
Type
IP
Type
IP
1
10
3S
54
6 and 6P
67
2
11
4 and 4X
55
12 and 12K
52
3
54
5
52
13
54
3R
14
Acronyms
ATEX
Atmosphère explosible
IEC
International Electrotechnical
Commission
CA
Canada
I.S.
Intrinsic Safety
CEC
Canadian Electrical Code (CSA
C22.1)
NFPA
National Fire
Protection Association
EPL
Equipment Protection Level
NEC
National Electrical Code
(NFPA 70)
EU
European Union
US
United States of America