A system, comprising: a first DC supply line, a battery device having a battery and an output coupled to the first DC supply line, the battery device being configured to output a first DC supply signal to the first DC supply line, a second DC supply line, a mains supply, an AC-DC converter having an input coupled to the mains supply and having an output coupled to the second DC supply line, the AC-DC converter being configured to output a second DC supply signal to the second DC supply line, and a first plurality of luminaires, each having a lamp and coupled to the first DC supply line and to the second DC supply line, wherein the first plurality of luminaires comprises at least two luminaires, characterized in that each one of the first plurality of luminaires comprises a corresponding luminaire driver, each luminaire driver comprising: a first interface configured to receive, via the first DC supply line, the first DC supply signal, a second interface configured to receive, via the second DC supply line, the second DC supply signal, at least one DC-DC converter having an input and an output and configured to power the lamp via the output, and a switch configured to forward the first DC supply signal to the input of the at least one DC-DC converter in a first switch position and to forward the second DC supply signal to the input of the at least one DC-DC converter in a second switch position. a first DC supply line, a battery device having a battery and an output coupled to the first DC supply line, the battery device being configured to output a first DC supply signal to the first DC supply line, a second DC supply line, a mains supply, an AC-DC converter having an input coupled to the mains supply and having an output coupled to the second DC supply line, the AC-DC converter being configured to output a second DC supply signal to the second DC supply line, and a first plurality of luminaires, each having a lamp and coupled to the first DC supply line and to the second DC supply line, wherein the first plurality of luminaires comprises at least two luminaires, characterized in that each one of the first plurality of luminaires comprises a corresponding luminaire driver, each luminaire driver comprising: a first interface configured to receive, via the first DC supply line, the first DC supply signal, a second interface configured to receive, via the second DC supply line, the second DC supply signal, at least one DC-DC converter having an input and an output and configured to power the lamp via the output, and a switch configured to forward the first DC supply signal to the input of the at least one DC-DC converter in a first switch position and to forward the second DC supply signal to the input of the at least one DC-DC converter in a second switch position. a first interface configured to receive, via the first DC supply line, the first DC supply signal, a second interface configured to receive, via the second DC supply line, the second DC supply signal, at least one DC-DC converter having an input and an output and configured to power the lamp via the output, and a switch configured to forward the first DC supply signal to the input of the at least one DC-DC converter in a first switch position and to forward the second DC supply signal to the input of the at least one DC-DC converter in a second switch position.