A luminaire comprising an LED lighting unit comprising at least one LED arrangement and at least one other component (12, 13, 15, R), the luminaire further comprising a power supply comprising: an input terminal arrangement for receiving a mains power supply (V in); an output terminal arrangement connected to the LED lighting unit and adapted to define, when connected to the LED lighting unit, a power supplied to the LED lighting unit; a first power converter (L1, D1, C) designed to convert the received mains power supply (Vin); a second power converter, separate to the first power converter, designed to convert the received mains power supply (Vin); a controller (S1, S2) adapted to selectively control which of the first and second power converters converts the mains power supply (Vin) and provides a converted mains power supply to the output terminal arrangement, to thereby switch the power supplied to the connected LED lighting unit between a power converted by the first power converter (L1, D1, C) and a power converted by the second power converter, characterized in that: the first power converter (L1, D1, C) is more efficient than the second power converter at converting the mains power supply (Vin) when the converted mains power supply (Vin) is at a first non-zero power level; and the second power converter is more efficient than the first power converter (L1, D1, C) at converting the mains power supply (Vin) when the converted mains power supply is at a second, different non-zero power level, wherein the first non-zero power level is sufficient to power the at least one LED arrangement of the LED lighting unit, and the second non-zero power level is not sufficient to power the at least one LED arrangement of the LED lighting unit, wherein the LED arrangement and the at least one other component (12, 13, 15, R) are adapted to draw power from a same power rail of the LED lighting unit, wherein the output terminal arrangement is coupled to the power rail. an input terminal arrangement for receiving a mains power supply (V in); an output terminal arrangement connected to the LED lighting unit and adapted to define, when connected to the LED lighting unit, a power supplied to the LED lighting unit; a first power converter (L1, D1, C) designed to convert the received mains power supply (Vin); a second power converter, separate to the first power converter, designed to convert the received mains power supply (Vin); a controller (S1, S2) adapted to selectively control which of the first and second power converters converts the mains power supply (Vin) and provides a converted mains power supply to the output terminal arrangement, to thereby switch the power supplied to the connected LED lighting unit between a power converted by the first power converter (L1, D1, C) and a power converted by the second power converter, characterized in that: the first power converter (L1, D1, C) is more efficient than the second power converter at converting the mains power supply (Vin) when the converted mains power supply (Vin) is at a first non-zero power level; and the second power converter is more efficient than the first power converter (L1, D1, C) at converting the mains power supply (Vin) when the converted mains power supply is at a second, different non-zero power level, wherein the first non-zero power level is sufficient to power the at least one LED arrangement of the LED lighting unit, and the second non-zero power level is not sufficient to power the at least one LED arrangement of the LED lighting unit, wherein the LED arrangement and the at least one other component (12, 13, 15, R) are adapted to draw power from a same power rail of the LED lighting unit, wherein the output terminal arrangement is coupled to the power rail. the first power converter (L1, D1, C) is more efficient than the second power converter at converting the mains power supply (Vin) when the converted mains power supply (Vin) is at a first non-zero power level; and the second power converter is more efficient than the first power converter (L1, D1, C) at converting the mains power supply (Vin) when the converted mains power supply is at a second, different non-zero power level, wherein the first non-zero power level is sufficient to power the at least one LED arrangement of the LED lighting unit, and the second non-zero power level is not sufficient to power the at least one LED arrangement of the LED lighting unit, wherein the LED arrangement and the at least one other component (12, 13, 15, R) are adapted to draw power from a same power rail of the LED lighting unit, wherein the output terminal arrangement is coupled to the power rail.