Explosion Proof LED Lighting FAQ

Q: What are the Explosion Proof lighting fixtures?

A: Explosion proof lights are high resistance lighting fixtures which can work in harsh condition zones such as refineries, railways, coal mines, factories, manufacturing sites, and other similar areas.

Q: How are the Explosion Proof lighting fixtures different from common lighting fixtures?

A: Explosion proof is a technique for operating equipment safely in areas where explosive gasses (such as hydrogen or hydrocarbons - methane, propane etc) may be present. Usually lighting requires electrical energy sufficient to cause ignition. Explosion proof lighting would require these components: explosion proof box with the switch or sensor/relay to turn the lights on or off electrical power in conduit from the source in a safe area to the switch box to the light. The conduit requires permanent packing at the ends to prevent gasses and flames from traversing the conduit. A light fixture that holds the bulb so it can't be broken and cause a spark and cast metal fixture to contain the ignition should it occur.

Q: Could you elaborate on this technique?

Explosion proof does not mean it doesn't spark! Metal tools may spark and ignite gases. Electrical equipment such as switches and relay contacts may spark in normal operation. Other equipment may have voltages and currents high enough to spark if accidentally shorted.

Explosion proof means that the items that may spark are isolated in conduit or explosion proof boxes that will contain the resulting ignition repeatedly and not allow it to propagate outside the box. To this end the box must be very heavy cast steel with precision ground mating surfaces and lots of bolts at joints with sufficient depth and minimal gap to quench escaping hot flames below ignition or implement threaded joints that quench flames from going around the threads. The boxes are not airtight and it is presumed they contain explosive gas vapors. If the volume is small the explosive force it must contain is significant but not huge.

The boxes then house switches, relays and electrical items with high voltage that may operate in classified hazardous areas.

Q: You said “classified” hazardous areas. How are hazardous areas classified?

A: In North America, hazardous locations are separated into three “Classes” based on the explosive characteristics of the materials. The Classes of material is further separated into “Divisions” or “Zones” based on the risk of fire or explosion that the material poses. The Zone system has three levels of hazard while the Division System has two levels.

Class I Locations 

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 ignitible mixtures. The terms, "gases or vapors" differentiates between materials that are in a gaseous state under normal atmospheric conditions, such as hydrogen or methane, and a vapor that is flashed off from a liquid, under normal atmospheric conditions, such as gasoline. 

The subdivision of Class I, locations into “Divisions” or “Zones” is based on the probability that an explosive gas atmosphere may be present in a location. 

The following chart will help how Class I locations are further defined into Division 1 and 2 and how each Division corresponds to Zones 0, 1, and 2:

Area Classification

Division 1:
Where ignitable concentrations of flammable gases, vapors, or liquids can exist all of the time or some of the time under normal operating conditions.
Zone 0:Where ignitable concentrations of flammable gases, vapors, or liquids are present continuously or for long periods of time under normal operating conditions.

Zone 1:
Where ignitable concentrations of flammable gases, vapors, or liquids are likely to exist under normal operating conditions.

Division 2:
Where ignitable concentrations of flammable gases, vapors, or liquids are not likely to exist under normal operating conditions.
Zone 2:
Where ignitable concentrations of flammable gases, vapors, or liquids are not likely to exist under normal operating conditions.

Class II Locations 

Class II locations are those which are hazardous due to the presence of combustible or electrically conductive dusts. The dust must be present in sufficient quantities for a fire or explosion hazard to exist. The fact that there is some combustible dust present does not mean a Class II hazardous location exists. 

Class II substances are divided into three groups for similar reasons to those of Class I materials: equipment design and area classification. Class II groups are based on different characteristics than those of Class I, given the requirements for an explosion to occur and the protection methods required for equipment. In Class II locations the ignition temperature, the electrical conductivity, and the thermal blanketing effect of the dust are critical when dealing with heat- producing equipment, such as lighting fixtures and motors. It is these factors which are the deciding factors in determining the Class II groups. 

The following chart summarizes how Class II locations are further defined into Divisions and Zones:

Area Classification

Class II, Division 1:
Where ignitable concentrations of combustible dust can exist all of the time or some of the time under normal operating conditions.
Zone 20:Where ignitable concentrations of ignitable fibers/flyings are present continuously or for long periods of time under normal operating conditions.

Zone 21:
Where ignitable concentrations of combustible dust or ignitable fibers/flyings are likely to exist under normal operating conditions.

Class II, Division 2:
Where ignitable concentrations of combustible dust are not likely to exist under normal operating conditions.
Zone 22:
Where ignitable concentrations of combustible dust or ignitable fibers/flyings are not likely to exist under normal operating conditions.

Class III Locations

Class III locations are places where easily ignitable fibers or materials producing combustible flyings are handled, manufactured, used, stored, or handled. It is further separated into Division 1 and 2: 

Division 1: where easily ignitable fibers or materials producing combustible flyings are handled, manufactured, used. 

Division 2: where easily ignitable fibers or materials producing combustible flyings are stored or handled. 

Q: You explained the location Classes, Divisions, and/or Zones. I saw some UL ratings on lighting fixtures are pertaining to Groups. What are they? 

A: Good question. Based on the types of materials present in each Division (or Zone), an area can be further classified into 4 Groups for Class I locations:

Groups

Division 1 and 2:
A acetylene
B hydrogen
C ethylene
D propane
For Class II locations, there are 3 groups:
Zone 0, 1, and 2:
IIC acetylene & hydrogen
IIB+H2 hydrogen
IIB ethylene
IIA propane

Groups

Class II, Division1 and 2:
E metal dust - Div. 1 only
F carbonaceous dust
G non-conductive dust
-
For Class III, there is no Group category.
Zone 20, 21, and 22:
IIICConductive dust
IIIBnon-conductive dust
IIIBnon-conductive dust
IIIAcombustible flyings

Q: Are LED Explosion Proof lighting fixtures available now? How do they compare to the traditional lighting fixtures?

A: Most explosion proof lighting are now manufactured using LED technology by top LED manufacturers. This is because LED lights are more energy saving & eco-friendly as compared to traditional bulbs. GreenLEDzone.com carries only the explosion proof LED lighting fixtures that are UL listed (for safety) and also DLC rated (for energy efficiency). 

Q: How are your explosion proof fixtures rated by UL as well as DLC? What are their features?

A: For the Defender series, the fixture comes with 80, 100, and 150W:

  • UL844 Listed for Hazardous Area Lights
    • Class I Division 1, Group C, D
    • Class I Division 2, Group A, B, C, D
    • Class II Division 2, Group F, G
    • Class III
  • UL 1598A Marine
  • DLC premium
  • AC100-277V, AC347-480V, 50/60HZ
  • Excellent lighting efficacy, up to 130 lumens per Watt (130lm/W)
  • Heavy duty copper-free aluminum housing
  • Mounting: ceiling, wall, or floor

For the Warrior series, the fixture comes with 45 and 65W:

  • UL 844 Listed for Hazardous Area Lights
    • Class I Division 2, Group A, B, C, D
    • Class II Division 1, Group E,F, G
    • Class II Division 2, Group F, G
    • Class III Division 1
  • UL1598A Marine
  • AC100-240/277V, 50/60Hz
  • Excellent lighting efficacy, up to 150 lumens per Watt (150lm/W)
  • Heavy duty copper-free aluminum housing
  • Mounting Options:Ceiling mount, wall mount(25° or 90°), pole mount(25° or 90°), adjustable bracket, adjustable pipe clamp, hanging pole mount.