The storage of class III liquids in buildings in connection with oil burning equipment shall be in accordance with the following:
Tanks of not over two hundred seventy five (275) gallons capacity each and having an aggregate capacity not in excess of five hundred fifty (550) gallons may be installed without enclosures. Other tanks shall be completely enclosed with a heat insulation equivalent to reinforced concrete not less than eight inches (8") in thickness with at least a six inch (6") space on sides between tank and concrete insulation filled with sand or well tampered earth, and with twelve inches (12") of sand on top of tank, either between tank and concrete slab or above concrete slab. (1961 Code)