Year when elevation of appliances was required

[Chris Bernhardt]

Does anyone know any history of about when the elevation requirement for equipment capable of igniting flammable vapors in a garage came into the model codes or NFPA 54? I have it narrowed down to between the mid 60's and 1988 UBC.

Thanks, Chris

I mistakenly originally posted this in the fireplace forum in case you see this same posting over there.