This non-ducted system includes the rooftop unit, ceiling controls, and wall thermostat, so you can cool down fast. Specs Capacity: 13,500 Btu per hour Airflow: 470 CFM (cubic feet per minute) Max wind coverage: 30' Dimensions and Weight: Air conditioner: 29-1/2" long x 27-5/8" wide. The Secondary Distribution Box (SDB) receives power from Main Power Distribution box via an extender cable and provides a central power distribution to feed normal branch circuits to the electric floor modules through snap-on extender cables. The SDB can be fitted with terminal blocks for custom. secondary unit substation is a close-coupled assembly consisting of enclosed primary high voltage equipment, three-phase power transformers, and enclosed secondary low voltage equipment. REFERENCES This. ACS takes the basic idea of zone wiring and combines it with pre-cut, pre-tested cable and plug-in connectors, to provide power and telecommunication systems that can be installed under raised floors (The Intelligent Floor), or in accessible ceilings (The Intelligent Ceiling). installed under. The power distribution boxes deliver electricity from the main electrical main to other circuits. Main Distribution Board (MDB) 2.