(1) Where there is only one egress door from a portable classroom, a fuel-fired appliance shall be separated from the remainder of the classroom by a fire separation with a fire-resistance rating of not less than 45 min. (2) Except as provided in Sentences (3) and (4), if a portable classroom contains a fuel-fired appliance, the appliance shall be separated from the remainder of the classroom by a fire separation having a fire-resistance rating not less than,
(a) 1.5 h where the horizontal distance between portable classrooms is 1.5 m or less, and
(b) 45 min where the horizontal distance between portable classrooms is more than 1.5 m. (3) If the horizontal distance between portable classrooms is 6 m or more, a fuel-fired appliance need not be separated from the remainder of the classroom by a fire separation provided,
(a) there is not more than one appliance per portable classroom, and
(b) the appliance is located not less than 4.5 m from an egress doorway or an exit from the portable classroom. (4) Fuel-fired appliances with sealed combustion located in a portable classroom are not required to be separated from the remainder of the classroom,
(a) if there are not more than four portable classrooms in a group, and
(b) if the appliance is located not less than 4.5 m from an egress doorway or an exit from the portable classroom.