A cable bus system for the mounting and positioning of high amperature, from low to high voltage electrical power cables transmitting polyphase electrical current. The cable bus system included a ventilated enclosure used to protect electrical cables mounted therein. The enclosure is provided with multiple modular cable trays which are bolted together in a stacked arrangement to form a single multi-level cable raceway. The enclosure is further provided with ventilated top and bottom covers which are secured respectively to the top and bottom of the uppermost and bottom most cable trays to define the enclosed metal circuit. The cable bus system is capable of transmitting the same highest allowable “free air” cable amperature in both above and underground installations, effectively improving the transmission of electrical power from one end to the other end, in installations where a transition of electrical power from below ground to above ground is either necessary or economically preferable. For the underground portion, the cable bus is installed in the encasement that is uniquely offset vented or power cooled to meet the cable high amperage requirements. The cable bus system is also suitable for high vertical rise installations when utilizing anti cable slip mechanism or technique.