A light engine (200; 300) comprising: an array of LEDs comprising at least one first string of first LEDs (102A-D) connected in series and adapted to output light having a first wavelength and comprising at least one second string of second LEDs (104A-D) connected in series and adapted to output light having a second wavelength longer than the first wavelength, wherein said at least one second string is connected in series with said at least one first string at a connection point; a power supply connected to the array for connection to a power source adapted to energize the LEDs; a temperature variable resistance component (202; 302) connected to the array at the connection point and a switch (204, 304) connected in series with the temperature variable resistance component (202; 302), wherein the temperature series connection comprising the variable resistance component (202; 302) and the switch (204, 304) is connected in parallel with the second string; a comparator (210; 310) configured to control the switch (204, 304) to selectively connect the temperature variable resistance component (202; 302) to the array of LEDs, thereby limiting the current applied to the LEDs of the second string during an initial energization of the LEDs prior to steady-state operation of the LEDs; a temperature sensitive circuit (208; 308) adapted to provide a temperature signal (213, 313) indicative of the temperature of at least one of the LEDs of the first string to the comparator (210; 310), wherein the temperature sensitive circuit (208; 308) comprises the temperature variable resistance component (202; 302); wherein the temperature variable resistance component (202; 302) is selected to have properties which correspond to the properties of the first string and is configured such that the period of time for the temperature variable resistance component (202; 302) to reach its maximum resistance is about the same as the period of time that it takes for the second string to reach steady state; and wherein the limiting is substantially reduced by the comparator (210; 310) and the switch (204, 304) depending on the temperature signal. an array of LEDs comprising at least one first string of first LEDs (102A-D) connected in series and adapted to output light having a first wavelength and comprising at least one second string of second LEDs (104A-D) connected in series and adapted to output light having a second wavelength longer than the first wavelength, wherein said at least one second string is connected in series with said at least one first string at a connection point; a power supply connected to the array for connection to a power source adapted to energize the LEDs; a temperature variable resistance component (202; 302) connected to the array at the connection point and a switch (204, 304) connected in series with the temperature variable resistance component (202; 302), wherein the temperature series connection comprising the variable resistance component (202; 302) and the switch (204, 304) is connected in parallel with the second string; a comparator (210; 310) configured to control the switch (204, 304) to selectively connect the temperature variable resistance component (202; 302) to the array of LEDs, thereby limiting the current applied to the LEDs of the second string during an initial energization of the LEDs prior to steady-state operation of the LEDs; a temperature sensitive circuit (208; 308) adapted to provide a temperature signal (213, 313) indicative of the temperature of at least one of the LEDs of the first string to the comparator (210; 310), wherein the temperature sensitive circuit (208; 308) comprises the temperature variable resistance component (202; 302); wherein the temperature variable resistance component (202; 302) is selected to have properties which correspond to the properties of the first string and is configured such that the period of time for the temperature variable resistance component (202; 302) to reach its maximum resistance is about the same as the period of time that it takes for the second string to reach steady state; and wherein the limiting is substantially reduced by the comparator (210; 310) and the switch (204, 304) depending on the temperature signal.