An improved enclosure for housing communications and electronics equipment comprises a heating element fabricated with a positive temperature coefficient material. The enclosure is particularly useful for housing communications equipment and cell site base stations for cellular telephone systems in the outdoors; it has self-regulating heating capabilities that are not dependent upon voltage parameters, thereby enabling its use in diverse geographic locations. In a preferred embodiment, a plurality of PTC heating elements are used and selectively located adjacent a plurality of circuitry regions. DC power may be used to energize the PTC heaters, and the enclosure may be used for telephone equipment operating with AC or DC power.