MDC series metal distribution boxes are designed for safe, reliable distribution and control of electrical power as service entrance equipment in residential, commercial and light industrial premises. The are available in DIN-rail designs for indoor applications. Features ○Made out of high quality. The 40VMD multiport distribution controller (MDC) is a distribution box for refrigerant to multiple indoor fan coil units installed in a given heat recovery system. The equipment is initially protected under the manufacturer's standard warranty; however, the warranty is provided under the condition. At its core, a distribution box, also known as a distribution board, panelboard, or fuse box, is a protective enclosure that houses all the electrical components that control and protect the circuits in a building. Main Distribution Board (MDB) 2.