A control and supply system for electrical devices comprises at least one voltage supply and control device above sea level, a subsea cable connecting the voltage supply and control device with the electrical devices, and a control and actuating device which is associated essentially in situ with the electrical devices. The control and supply system allows supplies over larger distances, uses fewer devices, obtains higher efficiency and makes better use of the system. In order to achieve this, the voltage supply and control device comprises at least one AC/DC converter for producing a direct voltage in order to feed the subsea cable. The control and actuating device is associated with at least one DC/DC or DC/AC converter for converting the DC voltage transmitted by the sub-sea cable into a DC voltage or an AC voltage. The voltage generated thereby can be transmitted to the electrical device via a connecting line.