(1) Except as provided in Sentences (2) and (3) and Article 7.4.5.2., every fixture shall be protected by a separate trap.
(2) One trap may protect,
(a) all the trays or compartments of a two or three compartment sink,
(b) a two or three compartment laundry tray, or
(c) two similar type single compartment fixtures located in the same room.
(3) One trap may serve a group of floor drains and hub drains, a group of shower drains, a group of washing machines or a group of laboratory sinks if the fixtures,
(a) are in the same room, and
(b) are not located where they can receive food or other organic matter.
(4) Reserved
(5) A grease interceptor shall not serve as a fixture trap and each fixture discharging through the interceptor shall be trapped and vented.
(6) Where a domestic dishwashing machine equipped with a drainage pump discharges through a direct connection into the fixture outlet pipe of an adjacent kitchen sink or disposal unit, the pump discharge line shall,
(a) rise as high as possible to just under the counter, and
(b) connect,
(i) on the inlet side of the sink trap by means of a Y fitting, or
(ii) to the disposal unit.