An electrical box assembly includes an electrical box and a plurality of partition plates to divide the electrical box into separate compartments to accommodate high voltage wiring device and low voltage wiring devices. The partition plates generally have an angled portion so that compartments can access a knockout in the bottom wall of the electrical box. A plurality of device frames are positioned above the partition plates and coupled to a central support member in the electrical box and a side wall of the electrical box to support an electrical wiring device in the compartments. A cover plate having a configuration corresponding substantially to the shape of the device frame is attached to the device frame and side wall. The cover plate has an opening adapted to receive the wiring device.