501.130(B)(1) CLD2 Luminaire Surface Temperature Measurement

[jtinge]

NEC states that the surface temperature of a luminaire in a C1D2 location cannot exceed 80% of the ignition temperature of the gas involved. One reference states that the luminaire surface temperature is measured on the hottest part of the fixture-either inside or outside, but another states that it's the lamp surface temperature not the luminaire surface temperature that must not exceed the 80% gas ignition temperature. Which is the correct interpretation of the code requirement?

 

[rbalex]

Section 501.130 (B)(1) is a very long “run-on” sentence. But, if read carefully, there are two options. One, if the lamp is of a type to exceed 80% ignition temperature, the luminaire must be identified for Division 1. The second option is the luminaire is specifically tested to determine its “T-Code”. It is the second option where the NRTL tests all internal surfaces.