HAZARDOUS LOCATION CLASSIFICATION
WHAT CONSTITUTES A HAZARDOUS LOCATION?
The classification of a given area as to Class, Division, and Group is solely
the judgment of THE OWNER, INSURANCE COMPANY, AND THE ­AUTHORITY
HAVING JURISDICTION.
Articles 500-517 of the National Electrical Code define, categorize and
provide the basic ground rules of the application and installation of ­lighting
fixtures in hazardous locations.
Hazardous locations are defined in terms of Class, Division and Group, per
the NEC. The definition of each is as follows:
“CLASS I locations are those in which flammable Gases or Vapors are or
may be present in the air in quantities sufficient to produce explosive or
ignitable mixtures.”
“CLASS II locations are those that are hazardous because of the presence
of Combustible Dust.”
“CLASS III locations are those that are hazardous because of the presence
of easily ignitable Fibers or Flyings, but in which such fibers or flyings are
not likely to be in suspension in the air in quantities sufficient to produce
ignitable mixtures.”
Each “CLASS” is further defined as either Division 1 or Division 2.
DIVISION 1 is an environment that is Normally Hazardous.
DIVISION 2 is an environment that is Not Normally Hazardous.
Each Division may be further classified according to the particular gas,
vapor or dust, by defining the areas by groups, see table below.
Don’t confuse UL844 with UL1598 which meets the standards for those
locations which require only enclosed and gasketed products.
You can’t readily differentiate between UL1598 and UL844 listed luminaires
by examining the product. So how do you tell one from the other? THE
BEST WAY TO BE SURE OF A UL844 LISTING IS TO EXAMINE THE LABEL AND
SEE THE WORDS “LISTED ELECTRIC LIGHTING FIXTURES FOR HAZARDOUS
LOCATIONS” OR “LISTED ELECTRIC LIGHTING FIXTURES FOR HAZARDOUS
LOCATIONS” IN CLOSE PROXIMITY TO THE CIRCULAR UL LOGO.
UL844 IS THE ONLY UL STANDARD FOR HAZARDOUS LOCATION
­LIGHTING
SUMMARY OF HAZARDOUS ATMOSPHERES*
NEC
CLASS
DIVISION
TYPICAL ATMOSPHERE AND
GROUP AUTOIGNITION TEMPERATURES
TEMPERATURE
MEASURED
I
1
A
Acetylene (305°C, 581°F)
Maximum
GASES,
Normally
exterior
VAPORS
hazardous B
Hydrogen (502°C, 986°F) manufactured temperature in
gases containing more than 30%
40°C ambient.
hydrogen (by volume)
H8 is in 25°C
C
ethylene (450°C, 842°F)
ambient
cyclopropane (503°C, 938°F)
D
hexanes (225°C, 437 °F)
butane (288°C, 550°F)
propane (450°C, 842°F
acetone (465°C, 869°F)
benzene (420°C, 788°F
gasoline (280-471°C, 536-880°F)
2**
A
Same as Division 1
Max interior
Not
B
Same as Division 1
temperature in
normally
C
Same as Division 1
40°C ambient.
hazardous D
Same as Division 1
P54H is in 25°C
ambient
LIMITING
VALUE
GE TYPE
ORDERING NUMBER
280°C (536°F) and
Not Available
Articles 500-503 of NEC
280°C (566°F) and
Articles 500-503 of NEC
180°C (356°F) and
Articles 500-503 of NEC
280°C (526°F) and
Articles 500-503 of NEC
H9
H8
Max temp of luminaire
not to exceed the autoignition temp (°C) of gas H2
or vapor involved. Ref.
Articles 500-503 of NEC
P54H
PMGA
MGH
II
1
E
Metal dust, including aluminum,
Max exterior
COMBUSTIBLE Normally
magnesium, and their commercial alloys, temperature in
DUSTS
hazardous
and other metals of similarly hazardous 40°C ambient
characteristics
with a dust
F
Carbon black, coal, coke dust
blanket.
H8 is in 25°C
G
Flour, starch, grain dusts.
ambient.
2**
G
Same as Division 1
Max exterior
Not
temp under
normally conditions of
hazardous
use
III
1, 2
Same as Class II, Division 2
Same as Class
EASILY
II, Div. 2
IGNITIBLE
FIBERS AND
FLYINGS
200°C (392°F) and
Articles 500-503 of NEC
H2
200°C (392°F) and
Articles 500-503 of NEC
165°C (329°F) and
Articles 500-503 of NEC
165°C (329°F) and
Articles 500-503 of NEC
H9
MGH
H8
FP2
165°C (329°F) and
Articles 500-503 of NEC
H2
MGH
* Information for this table is extracted from the National Electrical Code (NEC), Article 500, and from the National Fire Prevention Association’s “National Electrical Code Handbook,”
(reference to NFPA 497M).
** Not normally hazardous means that the gases or dusts are not normally present.
The classification of a given area as to Class, Division, and Group is solely the judgement of THE OWNER, INSURANCE COMPANY, AND THE AUTHORITY HAVING JURISDICTION.
GE Lighting Solutions • 1-888-MY-GE-LED • www.gelightingsolutions.com
1-888- 6 9 - 4 3-5 3 3
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HAZARDOUS MATERIAL COMMONLY ENCOUNTERED
As a guide for THE OWNER, RESPONSIBLE INSURANCE COMPANY, AND
THE AUTHORITY HAVING JURISDICTION in determining the proper NEC
Group classification for a flammable gas, to use the following table is
reprinted from the “Manual for Classification of Gases, Vapors and Dusts
for Electrical Equipment in Hazardous (Classified) Locations” NFPA 497M
and lists the Autoignition Temperature (AIT) of gases and vapors of liquids
with Flash Points below 100°F (37°C). It also lists Group Classifications for
the gases as determined by tests (indicated by *) or based on analogy
with tested materials and on chemical structure. While the classification
of the untested materials represents the best judgement of two groups
of experts, it is conceivable that the Group Classification of any particular
untested material may be incorrect.
In certain instances, therefore, it may be advisable to submit untested
materials to a qualified testing laboratory for verification of the assigned
Group ­Classification.
NOTE: The temperature and Group Classifications are subject to change.
Consult the latest edition of NFPA 497M for the most recent information.
NOTE: Reprinted with permission from NFPA 497M, Classification of Class
I Hazardous Locations for Electrical Installations, National Fire Protection
Association, Quincy, MA 02269. This reprinted material is not the ­complete
and official position of the NFPA on the referenced subject which is
­represented only by the standard in its entirety.
GROUP CLASSIFICATION AND AUTOIGNITION TEMPERATURE (AIT) OF SELECTED FLAMMABLE GASES
AND VAPORS OF LIQUIDS HAVING FLASH POINTS BELOW 100°F (37.8°C).
MATERIAL
ACETALDEHYDE
ACETONE
ACETONITRILE
ACETYLENE
ACROLEIN (INHIBITED)
ACRYLONITRILE
ALLYL ALCOHOL
ALLYL CHLORIDE
AMMONIA
N-AMYL ACETATE
SEC-AMYL ACETATE
BENZENE
1,3-BUTADIENE
BUTANE
1-BUTANOL
2-BUTANOL
N-BUTYL ACETATE
ISO-BUTYL ACETATE
SEC-BUTYL ACETATE
BUTYLAMINE
BUTYLENE
BUTYL MERCAPTAN
N-BUTYRALDEHYDE
CARBON DISULFIDE
CARBON MONOXIDE
CHLOROBENZENE
CHLOROPRENE
CROTONALDEHYDE
CUMENE
CYCLOHEXANE
CYCLOHEXENE
CYCLOPROPANE
1,1-DICHLOROETHANE
1,2-DICHLOROETHYLENE
1,3,-DICHLOROPROPENE
DICYCLOPENTADIENE
DIETHYL ETHER
DIETHYLAMINE
DI-ISOBUTYLENE
DI-ISOPROPYLAMINE
DIMETHYLAMINE
1,4-DIOXANE
DI-N-PROPYLAMINE
EPICHLOROHYDRIN
ETHANE
ETHANOL
AIT
GROUP °F
C*
347
D*
869
D
975
A*
581
1
B(C)* 455
D*
898
C*
713
D
905
2
D*
928
D
680
D
–
D*
928
B(D)*1 788
D*
550
D*
650
D*
761
D*
790
D*
790
D
–
D
594
D
725
C
–
C*
425
3
-*
194
C*
1128
D
1099
D
–
C*
450
D
795
D
473
D
471
D*
938
D
820
D
860
D
–
C
937
C*
320
C*
594
D*
736
C
600
C
752
C
356
C
570
C*
772
D*
882
D*
685
°C
175
465
524
305
235
481
378
485
498
360
–
498
420
288
343
405
421
421
–
312
385
–
218
90
609
593
–
232
424
245
244
503
438
460
–
503
160
312
391
316
400
180
299
411
472
363
AIT
MATERIAL
GROUP °F
ETHYL ACETATE
D*
800
ETHYL ACRYLATE (INHIBITED) D*
702
ETHYLAMINE
D*
725
ETHYL BENZENE
D
810
ETHYL CHLORIDE
D
966
ETHYLENE
C*
842
ETHYLENEDIAMINE
D*
725
ETHYLENE DICHLORIDE
D*
775
ETHYLENIMINE
C*
608
1
ETHYLENE OXIDE
B(C)* 804
ETHYL FORMATE
D
851
ETHYL MERCAPTAN
C*
572
N-ETHYL MORPHOLINE
C
–
FORMALDEHYDE (GAS)
B
795
GASOLINE
D*
536-880
HEPTANE
D*
399
HEPTENE
D
500
HEXANE
D*
437
2-HEXANONE
D
795
HEXENES
D
473
HYDROGEN
B*
968
HYDROGEN CYANIDE
C*
1000
HYDROGEN SELENIDE
C
–
HYDROGEN SULFIDE
C*
500
ISOAMYL ACETATE
D
680
ISOBUTYL ACRYLATE
D
800
ISOBUTYRALDEHYDE
C
385
ISOPRENE
D*
428
ISOPROPYL ACETATE
D
860
ISOPROPYLAMINE
D
756
ISOPROPYL ETHER
D*
830
ISOPROPYL GLYCIDYL ETHER C
–
LIQUEFIED PETROLEUM GAS D
761-842
MANUFACTURED GAS (CONTAINING
MORE THAT 30% H2 BY VOLUME) B*
–
MESITYL OXIDE
D*
652
METHANE
D*
999
METHANOL
D*
725
METHYL ACETATE
D
850
METHYLACETYLENE
C*
–
METHYLACETYLENE-PROPADIENE
(STABILIZED)
C
–
METHYL ACRYLATE
D
875
METHYLAMINE
D
806
METHYLCYCLOHEXANE
D
482
METHYL ETHER
C*
662
NOTES TO TABLE
*Material has been classified by test.
1 If equipment is isolated by sealing out conduit 1/2-in. (12.7mm)
or larger, in accordance with Article 501-5(a) of NFPA 70, National
Electrical Code, equipment for the group classification shown in a
parenthesis is permitted.
2 For Classification of areas involving ammonia, see Safety Code for
Mechanical Refrigeration, ANSI/ASHRAE 15, and Safety Requirements
for the Storage and Handling of Anhydrous Ammonia, ANSI/CGA
G2.1
°C
427
372
385
432
519
450
385
413
320
429
455
300
–
429
280-471
204
260
225
424
245
520
538
–
260
360
427
196
220
460
402
443
–
405-450
–
344
537
385
454
–
–
468
430
250
350
MATERIAL
METHYL ETHYL KETONE
METHYL FORMAL
METHYL FORMATE
METHYL ISOBUTYL KETONE
METHYL ISOCYANATE
METHYL MERCAPTAN
METHYL METHACRYLATE
2-METHYL-1-PROPANOL
2-METHYL-2-PROPANOL
MONOETHYL HYDRAZINE
NAPHTHA (PETROLEUM)
NITROETHANE
NITROMETHANE
1-NITROPROPANE
2-NITROPROPANE
NONANE
NONENE
OCTANE
OCTENE
PENTANE
1-PENTANOL
2-PENTANONE
1-PENTENE
PROPANE
1-PROPANOL
2-PROPANOL
PROPRIONALDEHYDE
N-PROPYL ACETATE
PROPYLENE
PROPYLENE DICHLORIDE
PROPYLENE OXIDE
N-PROPYL ETHER
PROPYL NITRATE
PYRIDINE
STYRENE
TERTAHYDROFURAN
TOLUENE
TRIETHYLAMINE
TURPENTINE
UNSYMMETRICAL DIMETHYL
HYDRAZINE (UDMH)
VALERALDEHYDE
VINYL ACETATE
VINYL CHLORIDE
VINYLIDENE CHLORIDE
XYLENES
AIT
GROUP °F
D*
759
C*
460
D
840
D*
840
D
994
C
–
D
792
D*
780
D*
892
C
382
4
D*
550
C
778
C
785
C
789
C*
802
D
401
D
–
D*
403
D
446
D*
470
D*
572
D
846
D
527
D*
842
D*
775
D*
750
C
405
D
842
D*
851
D
1035
1
B(C)* 840
C*
419
B*
347
D*
900
D*
914
C*
610
D*
896
C*
–
D
488
C*
C
D*
D*
D
D*
480
432
756
882
1058
°C
404
238
449
449
534
–
422
416
478
194
288
414
418
421
428
205
–
206
230
243
300
452
275
450
413
399
207
450
455
557
449
215
175
482
490
321
480
–
253
249
222
402
472
570
867-984 464-529
3 Certain chemicals may have characteristics that require ­safeguards
beyond those required for any of the above groups. Carbon Disulfide
is one of these chemicals because of its low autoignition temperature
and small joint clearance to arrest flame propagation.
4 Petroleum Naptha is a saturated hydrocarbon mixture whose boiling
range is 20° to 135°C. It is also known as benzine, ligroin, petroleum
ether, and naptha.
References: Autoignition temperatures listed above are the lowest value
for each material as listed in NFPA 325M, Fire Hazard ­Properties of
­Flammable Liquids, Gases, and Volatile Solids, or as reported in an article
by Hilado, C. J. and Clark, S.W., in Chemical Engineering,
September 4, 1972.
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