Class I, Gas or Vapor
(NEC Article 500-5, 5001-9)
Areas where inflammable gases or vapors may be present in sufficient quantities to produce an explosive or flammable mixture.
Class II, Dust
(NEC Article 500-6, 502-11)
Areas where combustible dusts are present in sufficient quantities to produce a hazardous environment.
Class III, Fiber
(NEC Article 500-7, 503-9)
Areas where ignitable fibers or flyings are present in sufficient quantities to produce ignitable mixtures
Division 1, Always Present
(NEC Article 500-5a, 500-6a, 500-7a, 502-11a)
Areas where the hazardous condition is normally present, either continuously or periodically.
Division 2, Not Normally Present
(NEC Article 500-5b, 500-6b, 500-7b, 500-9b, 502-11b)
Areas where the hazardous condition is present due to accidental rupture, release, breakage, or unusual faulty operation of a closed container or system.
IEC publication 79-10 defines the guidelines for classifying hazardous area. Instead of using Classes and Divisions, the term Zones is used as defined below.
Zone 0 – Is an area in which an explosive gas or vapor is continuously present or present for long periods, typically more than 1,000 hours per year. Generally,
most industrial users try to keep all electrical equipment out of the Zone 0 area. The only equipment approved is intrinsically safe equipment.
Zone 1 – Is an area in which an explosive gas atmosphere is likely to occur in normal conditions for more than 10 hours per year and less than 1,000 hours per year.
Zone 2 – Is defined as an area in which explosive gas or vapor atmospheres are not likely to occur and if it does, it is only for a short period of time, typicaly less than 10 hours per year.
Zone 20 – Is an explosive atmosphere, resulting from dust which is present continuously.
Zone 21 – This is defined as an atmosphere where dust is occasionally present.
Zone 22 – This is defined as an atmosphere where dust is not normally present. NOTE: Class III locations (fibers & flyings) are covered in Zone 20, 21, & 22.
| Hazardous Material | NEC U.S. Standards |
IEC Euronorm Standards | Maximum Surface Temperatures | T-Code* | Maximum Surface Temperatures | T-Code* | |||
| Gas or Vapor | Class I, Div. 1 Class I, Div. 2 | Zone 0 & Zone 1 Zone 2 | |||||||
| °C | °F | °C | °F | ||||||
| 450 | 840 | T1 | 180 | 356 | T3A | ||||
| Dust | Class II, Div. 1 Class II, Div. 2 | Zone 20 and Zone 21 Zone 22 | 300 | 572 | T2 | 165 | 329 | T3B | |
| 280 | 536 | T2A | 160 | 320 | T3C | ||||
| 260 | 500 | T2B | 135 | 275 | T4 | ||||
| Fibers or Flyings | Class III, Div. 1 Class III, Div. 2 | Zone 20 and Zone 21 Zone 22 | 230 | 446 | T2C | 120 | 248 | T4A | |
| 215 | 419 | T2D | 100 | 212 | T5 | ||||
| 200 | 392 | T3 | 85 | 185 | T6 | ||||
| * Based on 40°C (104°F) ambient For complete information, refer to the National Electric Code (NEC) | |||||||||
| IP Code is a coding system to indicate the degree of protection by an enclosure against access to hazardous parts, ingress of solid objects, ingress of water, and to give additional information in connection with such protection. | |||
| First Character indicates the degree of protection against the ingress of solid objects. | Second Character indicates the degree of protection against the ingress of water with harmful effects. | ||
0 |
Non-protected | 0 |
Non-protected |
1 |
Protected against solid foreign objects of 50 mm diameter or greater | 1 |
Protected against vertically falling water drops |
2 |
Protected against solid foreign objects of 12.5 mm diameter or greater | 2 |
Protected against vertically falling water drops as the enclosure is tilted 15° |
3 |
Protected against solid foreign objects of 2.5 mm diameter or greater | 3 |
Protected against spraying water |
4 |
Protected against solid foreign objects of 1.0 mm diameter or greater | 4 |
Protected against splashing water |
5 |
Dust-protected | 5 |
Protected against water jetting |
6 |
Dust-tight | 6 |
Protected against powerful water jetting |
7 |
Protected against temporary immersion | ||
8 |
Protected against continuous immersion | ||
| Number | Title |
| 844 | Luminaires for Use in Hazardous (Classified) Locations |
| 924 | Emergency Lighting and Power Equipment |
| 1598 | Luminaires |
| 1598A | Supplemental Requirements for Luminaires For Installation on Marine Vessels |
| 8750 | LED Equipment |
| Task Area Area | Footcandles | Task Area Area | Footcandles |
| Paint Booths | 100 - 150 | Areas with VDTs | 75 |
| Corridors/Stairways/Rest rooms | 10 - 20 | Classrooms | 50 - 75 |
| Storage Rooms | 10 - 50 | Cafeterias | 50 |
| Conference Rooms | 20 - 50 | Gymnasiums | 30 - 50 |
| General Offices | 50 - 100 | Manufacturing Assembly | 50 - 500 |
| Drafting/Accounting | 100 - 200 | Parking Areas (uncovered) | 1 - 2 |
