A lighting device (100, 500) comprising a power supply (10, 50), a controller (30, 70) and a power bus (20, 60); wherein the power supply (10, 50) is adapted to feed the power bus (20, 60); wherein the power bus (20, 60) comprises a plurality of power outputs (21, 61), wherein at least one power output (211, 212, 213, 214, 611, 612, 613) of said plurality of power outputs (21, 61) is adapted to electrically connect to a respective one of at least one load (111, 112, 113, 511, 512, 513); characterised in that the controller (30, 70) is arranged to: - select a time-interval; - convey a cryptographic message to one or more respective load of said at least one load before initiation of said time-interval, wherein the cryptographic message is indicative of an instruction for said one or more respective load of said at least one load to consume a predetermined amount of power from the power bus during said selected time-interval; - determine the power consumed from the power bus during said selected time-interval; - determine a condition indicative of an unauthorized load connected to said power bus when said determined power consumed from the power bus is different to a sum of each amount of power indicated in the cryptographic message to said one or more respective load of said at least one load; - in response to determining said condition, perform at least one action. wherein the power supply (10, 50) is adapted to feed the power bus (20, 60); wherein the power bus (20, 60) comprises a plurality of power outputs (21, 61), wherein at least one power output (211, 212, 213, 214, 611, 612, 613) of said plurality of power outputs (21, 61) is adapted to electrically connect to a respective one of at least one load (111, 112, 113, 511, 512, 513); characterised in that the controller (30, 70) is arranged to: - select a time-interval; - convey a cryptographic message to one or more respective load of said at least one load before initiation of said time-interval, wherein the cryptographic message is indicative of an instruction for said one or more respective load of said at least one load to consume a predetermined amount of power from the power bus during said selected time-interval; - determine the power consumed from the power bus during said selected time-interval; - determine a condition indicative of an unauthorized load connected to said power bus when said determined power consumed from the power bus is different to a sum of each amount of power indicated in the cryptographic message to said one or more respective load of said at least one load; - in response to determining said condition, perform at least one action. - select a time-interval; - convey a cryptographic message to one or more respective load of said at least one load before initiation of said time-interval, wherein the cryptographic message is indicative of an instruction for said one or more respective load of said at least one load to consume a predetermined amount of power from the power bus during said selected time-interval; - determine the power consumed from the power bus during said selected time-interval; - determine a condition indicative of an unauthorized load connected to said power bus when said determined power consumed from the power bus is different to a sum of each amount of power indicated in the cryptographic message to said one or more respective load of said at least one load; - in response to determining said condition, perform at least one action.