He was born in the Lebreton Flats area of Ottawa in 1855. He began work as a telegraph operator with the J.R. Booth Company, later becoming a manager in several early telephone companies in Ottawa, including the Bell Telephone Company office in Ottawa. In 1882, he founded the firm of Ahearn & Soper, electrical contractors, with Warren Soper. In the same year, Ahearn set up telephone service for Parliament Hill and government offices. Ahearn and Soper set up thousands of electric lights on the Parliament Buildings for Queen Victoria's Diamond Jubilee in 1887. Ahern invented the electric cooking range in 1882, and, in 1892, was the first person to prepare a meal on an electric stove which he built in the Windsor Hotel in Montreal.