A LED lamp for use in an existing light fixture having an electrical receptacle comprises an at least partially optically transmissive enclosure and a base having an external size that may be the same size or smaller than an external size of the electrical receptacle. A LED assembly is operable to emit light when energized through an electrical path from the base. The base comprises a universal mounting mechanism for mounting the lamp to the light fixture. A surge protector and an electrical connector are positioned at least partially in the base and are in the electrical path. A heat sink comprises a first portion in the enclosure for supporting the LED assembly and a second portion external of the enclosure for dissipating heat. The base is connected to the heat sink.