A lighting device comprising a power supply , a controller and a power bus ; wherein the power supply is adapted to feed the power bus ; wherein the power bus comprises a plurality of power outputs , wherein at least one power output of said plurality of power outputs is adapted to electrically connect to a respective one of at least one load ; characterised in that the controller 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 is adapted to feed the power bus ; wherein the power bus comprises a plurality of power outputs , wherein at least one power output of said plurality of power outputs is adapted to electrically connect to a respective one of at least one load ; characterised in that the controller 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. <EOS>