A transformer unit includes a first isolation transformer, a second isolation transformer and a power transformer. A single package incorporates the first isolation transformer, the second isolation transformer and the power transformer. A plurality of connection pins provide connections to the first isolation transformer, to the second isolation transformer and to the power transformer. A process is also provided for connecting transmission lines to a network device including providing transmission lines carrying an electrical supply current, sufficient to power the network device, concurrently with a network data signal. The single unit has the first integrated isolation transformer the second integrated isolation transformer and the power transformer. Some of the transmission lines are connected to the first isolation transformer to isolate transmission signals on the sending transmission lines from a transmitter of the network device. Some other transmission lines are connected to the second isolation transformer to isolate transmission signals on the receiving transmission lines from a receiver of the device. Within the single unit each of the first isolation transformer and the second isolation transformer are connected to the power transformer. The power transformer is used to supply power to the circuit board of the network devise at a potential which is reduced compared to a potential of said transmission lines carrying the electrical supply current.