(1) Except as permitted in Sentences (2) to (4), the requirement for fire dampers described in Sentence 3.1.8.7. (1) is permitted to be waived for,
(a) ducts that serve commercial cooking equipment,
(b) continuous noncombustible ducts having a melting point above 760°C that penetrate a vertical fire separation required by Sentence 3.3.1.1. (1) between suites of assembly, mercantile, low hazard industrial, medium hazard industrial or high hazard industrial occupancy,
(c) ducts or air-transfer openings that penetrate a vertical fire separation not required to have a fire-resistance rating, and
(d) noncombustible ducts or air-transfer openings that penetrate a horizontal fire separation not required to have a fire-resistance rating.
(2) The requirement for fire dampers described in Sentence 3.1.8.7. (1) is permitted to be waived for noncombustible branch ducts having a melting point above 760°C that penetrate a fire separation,
(a) provided the ducts,
(i) have a cross-sectional area not more than 130 cm2 and serve only air-conditioning units or combined air-conditioning and heating units discharging air not more than 1.2 m above the floor, or
(ii) extend not less than 500 mm inside exhaust duct risers that are under negative pressure and in which the airflow is upward as required by Article 3.6.3.4., or
(b) provided the fire separation separates a vertical service space from the remainder of the building and provided each individual duct exhausts directly to the outdoors at the top of the vertical service space.
(3) In elementary and secondary schools, a continuous noncombustible duct having a melting point above 760°C that pierces a fire separation having a fire-resistance rating of 30 min need not be equipped with a fire damper at the fire separation.
(4) In a Group B, Division 3 occupancy which contains sleeping accommodation for not more than 10 persons, which has not more than six occupants who require assistance in evacuation in case of an emergency and which is equipped with a fire alarm system, a duct need not be equipped with a fire damper at a fire separation, provided duct-type smoke detectors have been installed to control smoke circulation as described in Article 3.2.4.13.