A light engine assembly that includes a LED having a standard preselected output. The light engine assembly accepts a light guide into the assembly. The assembly includes a two-sided PCB, one side of which is a heat sink to reduce heat build-up on the board and the other side of which is a circuit that provides power to a LED positioned on the board. The circuit includes a connector for connection to a power supply and circuitry that regulates the current supplied to the LED, which is housed on the PCB. The assembly further includes a housing for the PCB that carries the PCB while protecting it from damage. The housing permits ventilation for cooling the board. The housing also includes a light guide holder barrel, which has a substantially square cross-section and is open at one end. The light guide holder barrel accepts a light guide having a substantially circular cross-section, the light guide contacting the light guide holder barrel in four positions, the light guide transmitting light from the LED when the LED is energized. The light guide can be rotated in any position and inserted into the light guide holder barrel to allow light to be transmitted in any preselected direction by the user.