Chapter 9, Section 904.3.1.1, is hereby deleted in its entirety and the following provision shall be substituted therefor:

Supported by Ground. Where a furnace is supported by the ground, it shall be installed on a concrete slab or an approved material, not less than 3 inches (76mm) above the adjoining ground level.

Chapter 9, Section 904.3.1.3, is hereby deleted in its entirety and the following provision shall be substituted therefor:

Excavation. – Where excavation is necessary to install a furnace, it shall extend to a depth of 6 inches (152mm) below and 12 inches (305 mm) on all sides of the furnace, except the service side, which shall have 30 inches (762 mm). Where the depth of the excavation for either the furnace or passageway exceeds 12 inches (305 mm), walls shall be lined with concrete or masonry or an approved material, 4 inches (102 mm) above the adjoining ground level.