(1) The trap arm of a fixture that has a hydraulic load of not more than 1 ½ fixture units may be connected to the vertical section of a circuit vent, additional circuit vent, offset relief vent or yoke vent, provided that,
(a) not more than two fixtures are connected to the vent pipe,
(b) where two fixtures are connected to the vent pipe, the connection is by means of a double fitting, in accordance with Table 7.2.4.5., and
(c) the section of the vent pipe that acts as a wet vent conforms to the requirements regarding wet vents.