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. <EOS>