(1)
Where a covering or a lining is used with a duct, such lining or covering shall have a flame-spread rating conforming to Article 3.6.5.4. or 9.33.6.4.
Where a covering or a lining is used with a duct, such lining or covering shall have a flame-spread rating conforming to Article 3.6.5.4. or 9.33.6.4.