1. Luminant Power – Fossil Engineering and Support
Acceptable Classified Luminaires
Prepared by: Sean McQuay
Last Revised: 26 November 2014

2. Luminant Power – Fossil Engineering and Support 2
Acceptable Classified Luminaires
Table of Contents
Section 1: Purpose......................................................................................................................................3
Section 2: Luminant Classified Locations...............................................................................................4
2.1 Hydrogen Storage: .....................................................................................................................4
2.2 Battery Rooms:...........................................................................................................................4
2.3 Unventilated Fuel Storage: .......................................................................................................4
2.4 Fuel Handling:............................................................................................................................4
Section 3: Class II Division 2 Luminaires...............................................................................................5
3.1 Operating Requirements:..........................................................................................................5
3.2 Operating Considerations:........................................................................................................6
Section 4: Detection of Classification Excursions: ................................................................................7

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Acceptable Classified Luminaires
Section 1: Purpose
This document serves to aid employees in understanding the luminaire classifications
present at Luminant sites and in selecting appropriate luminaires for classified
Luminant locations. Furthermore, this document serves to help employees identify
possible luminaire classification excursions in already installed luminaires throughout
the fleet.

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Acceptable Classified Luminaires
Section 2: Luminant Classified Locations
2.1 Hydrogen Storage:
Luminaires installed near hydrogen storage tanks may fall into the classification of Class
I Division 2 luminaires per ANSI C2-2007 127G.2. These classified locations include
outdoor hydrogen storage locations where luminaires may be installed within 4.6m from
the storage tanks, anywhere in enclosed ventilated and dedicated hydrogen storage
locations, and indoor ventilated hydrogen storage locations where luminaires may be
installed within 7.6m from storage tanks. There are no temperature classification
restrictions as the autoignition temperature of 500°C for hydrogen gas is greater than
the operating temperature of any classified luminaire.
2.2 Battery Rooms:
Luminant battery rooms are currently considered unclassified locations however it is the
strong recommendation that this be reviewed. Under rare circumstances, the buildup of
hydrogen gas may occur in these rooms and therefore Class I Division 2 luminaires
should be considered.
2.3 Unventilated Fuel Storage:
Luminaires installed in unventilated coal handling storage areas such as silos, above coal
piles, or any other enclosed and unventilated coal handling area must be strictly
classified as Class I Division 1 Group D. This classification requirement arises from the
inherent possibility of decomposing coal to emit methane gas. To be considered
adequately ventilated (and therefore reduced to Class II Division 2 Group F), the
concentration of methane gas must be maintained at or under 25% of the lower air/fuel
flammability limit per ANSI C2-2007 127A.1.
2.4 Fuel Handling:
Luminaires installed in coal tunnels or other coal handling spaces or areas where the
atmospheric concentration of entrapped volatiles will be at or above 8% will be classified

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Acceptable Classified Luminaires
as Class II Division 1 or Division 2 per ANSI C2-2007 127A.3. It is the Luminant
standard practice that luminaires selected for these locations are classified as Class II
Division 2 Group F.
Luminaires used in those locations classified as Class II Division 1 or Division 2 are not
necessarily required to also be classified strictly as Class II Division 1 or Division 2
luminaires but, whatever their classification, they still must comply with all of the
specifications pertaining to Class II Division 2 Group F luminaires. It is however,
strongly suggested that Class II Division 2 Group F luminaires be utilized whenever
possible to avoid unforeseen compliance excursions.
Section 3: Class II Division 2 Luminaires
3.1 Operating Requirements:
As most classified locations encountered in Luminant are classified as Class II Division 2
Group F, the scope of this article aims to cover the specific requirements for this location
only.
To be acceptable in locations classified as Class II Division 2 Group F, luminaires must
first be capable of preventing particulate matter ingress on the scale of coal. Both Class I
Division 1 and Division 2 and Class II Division 1 and Division 2 rated luminaires comply
with this requirement.
Furthermore, the luminaire must not exhibit a temperature greater than 165°C anywhere
on the superficies. To comply with this requirement, a Class I Division 1 or Division 2
luminaire must have a temperature rating of T3B or less. The temperature ratings can be
seen listed in the appended table. For a Class II Division 1 or Division 2 luminaire to
comply, it must be rated for Group F or Group G temperature operation. Class III
enclosures are unacceptable for Class II Division 1 or Division 2 locations.

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Acceptable Classified Luminaires
Maximum Temperature Temperature Class
(T Code)°C °F
450 842 T1
300 572 T2
280 536 T2A
260 500 T2B
230 446 T2C
215 419 T2D
200 392 T3
180 356 T3A
165 329 T3B
160 320 T3C
135 275 T4
120 248 T4A
100 212 T5
85 185 T6
*All maximum operating temperatures are based on a 40°C environment.
3.2 Operating Considerations:
If not selecting a luminaire that is specifically classified as Class II Division 2 Group F,
there are several considerations to be made. The first major consideration to make is the
operating temperature of the luminaire under a blanket of coal dust. Those luminaires
specifically rated for Group F operation have been developed and test-proven to
maintain a superficies temperature at or below 165°C even when limited heat transfer
occurs due to insulating coal accumulations on the luminaire. To prevent large
accumulations of coal dust from settling on the luminaire, further design considerations
are made for the superficies of those luminaires classified for use in Class II locations.

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Acceptable Classified Luminaires
Section 4: Detection of Classification Excursions:
As several luminaire classification excursions have been located throughout the fossil
fleet, this section aims to provide a few clues possibly viable in detecting further
classification excursions. In areas classified as Class II Division 2 Group F where
potential luminaire excursions are suspected, an initial pass should be made with
infrared thermography. With this method, it may be possible to detect luminaires with
temperatures exceeding the ratings for the classified location in which they are installed.
As listed in the appended table, the approximate operating temperature may provide a
clue as to the temperature rating of the luminaire and uncover possible excursions. It
should be noted however that infrared thermography does not provide a definite
verification of inappropriately installed luminaires. While operating in cooler ambient
temperatures, it is possible that the luminaire may display an acceptable operating
temperature yet actually carry a hotter temperature rating. Furthermore, the luminaire
may not possess adequate heat transfer while blanketed in coal and may exceed the safe
operating temperature. Care should also be taken while performing infrared
thermography to ensure that the superficies of the luminaire are being measured directly
and are not obscured by an insulating layer of coal dust.
It should be noted that there is currently no testing method that can identify with
complete accuracy, all luminaires installed in violation of the classified location. Infrared
thermography may of course bring to light those luminaires operating above specified
operating temperatures but many other factors may contribute to a luminaire with a
hotter temperature code appearing to be within specification. A trained eye may also
notice several design features of the luminaire, as the superficies of a luminaire classified
for Class II Division 2 Group F operation may be contoured in a way to prevent the
possible accumulation of excessive coal dust. This however may prove extremely difficult
to detect.
It is therefore recommended that manual verification of each luminaire be considered
the only method guaranteed to present complete accuracy. Any luminaires suspected of
exceeding the Class II Division 2 Group F temperature rating, falling short of the
particulate matter ingress standards of Class II luminaires, installed near hydrogen
storage locations per Section 2.1, or in rare circumstances falling short of the Class I

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Acceptable Classified Luminaires
Division 1 Group D standard for those luminaires in unventilated coal handling areas
should be replaced immediately with a luminaire suitable for use in the classified
location.
Typical Operating Temperature Temperature Class
(T Code)°C (min) °C (max)
351 450 T1
281 300 T2
261 280 T2A
231 260 T2B
216 230 T2C
201 215 T2D
181 200 T3
166 180 T3A
161 165 T3B
136 160 T3C
121 135 T4
101 120 T4A
86 100 T5
- 85 T6