An illuminating apparatus may include a housing and a lamp assembly to produce a beam of light transmitted to a fiber optic cable. An insulating device for insulating an input end of the fiber optic cable from beat may be disposed between the input end of the fiber optic cable and the lamp assembly. The insulating device may be a fused bundle of glass fiber that insulates the input end of the fiber optic cable. A method for retrofitting fiber optic light sources may include removing a fiber head from the light source and inserting a fiber optic glass to insulate the input end of a fiber optic cable from heat generated within the light source.