Electrical Equipments in Battery room

NickParker: Depends on whether the temp code is based on the actual hazard present (e.g., hydrogen with an AIT of 560 C), ... or if it was done based on the gas group that contains hydrogen (and other gases, such as butadiene at 414 C and acrolein at 234 C).

Obviously, if it was done according to the gas group, the allowable T code will be much reduced from that used in a "pure" hydrogen environment.

Converting energy to motion for more than half a century

@NickParker.
It's the LFL of that substance in air at those temperatures that matters. For equipment in explosive gases, requirements for T3 (<200 deg C) and T4 (<135 deg C) mean the surface temperatures are below specified. The idea is that the LFL (lower flammability limit) decreases slightly with the increase in temperature while the UFL increases a bit with temp rise. LFL stays at around 4% at 200 deg C while the UFL increases to about 80% (instead of 75% at room temperature). Here: