I think the rationale is that in a commercial repair garage, gasoline vapors would be far more common than in a residential setting. A residential garage is considered a "parking" garage, not a repair garage.Commercial repair garages
20-100 Scope (see Appendix B)
Rules 20-102 to 20-112 apply to commercial garages where vehicles powered by gasoline, propane, or other
flammable fuels are serviced or repaired.
20-102 Hazardous areas
(1) For each floor at or above grade, the entire area up to a level 50 mm above the floor shall be considered a
Class I, Zone 2 location except that adjacent areas shall not be classified as hazardous locations, provided
that they are
(a) elevated from a service and repair area by at least 50 mm; or
(b) separated from a service and repair area by tight-fitting barriers such as curbs, ramps, or partitions at
least 50 mm high.
(2) For each floor below grade, the entire area up to a level 50 mm above the bottom of outside doors or other
openings that are at, or above, grade level shall be considered a Class I, Zone 2 location except that, where
adequate ventilation is provided, the hazardous location shall extend up to a level of only 50 mm above
each such floor.
(3) Any pit or depression below floor level shall be considered a Class I, Zone 2 location that extends up to
50 mm above the floor level.
That's all we've got in the CEC
Sent from my SM-G975W using Tapatalk