What are the three NEC hazardous area classifications?
The National Electric Code classifies hazardous locations in three ways: TYPE, CONDITION, and NATURE. There are three types of hazardous conditions: Class I – gas and vapor, Class II dust, and Class III – fibers and flyings.
What are the classification of electrical area?
Class I: Denotes areas where flammable gas, vapor, or liquid is present. Class II: Denotes areas where combustible dust is present. Class III: Denotes areas where ignitable fibers are present. (Class III areas rarely exist in CTG facilities.)
How do you choose the hazardous area classification?
A Hazardous Area is defined by three main criteria, these being:
- The type of hazard (groups)
- The auto-ignition temperature of the hazardous material (temperature or “T” rating)
- The likelihood of the hazard being present in flammable concentrations (zones)
What is a Class 2 Div 2 area?
Division 2 is also a subset of Class II and is classified as an area where the explosive or flammable combustible dusts mentioned above are not likely to exist during regular operation.
What is Article 500 of the NEC?
Article 500 of NFPA 70, National Electrical Code , establishes the basis for classifying locations where fire or explosion hazards can exist due to flammable gases, flammable liquid–produced vapors, combustible liquid–produced vapors, combustible dusts, or ignitible fibers/flyings.
What is the difference between EXE and EXD?
To give a very basic summary of the two: Exe enclosures are deemed ‘explosion protected’ but not necessarily ‘flame proof’ Exd enclosures are ‘flame proof’ which means they should contain an explosion.
Is gas Group IIC better than IIB?
Any equipment which is marked as IIC can be used in atmospheres that contain Group IIB and Group IIA gasses. Conversely equipment marked IIA cannot be used in IIB or IIC explosive environments….Gas Groups.
| GAS GROUPS | TYPICAL GAS EXAMPLE |
|---|---|
| IIB | Coke Oven Gasses, Ethylene |
| IIC | Acetylene, Carbon Disulphide, Hydrogen |