James Kennedy Logan was born at West Kilbride, Ayrshire, Scotland, on 8 May 1844, the son of Marion Kennedy and her husband, Archibald Logan, who worked in the post office. He attended the parish school and Chalmers Private Academy. In August 1856, at the age of 12, he joined the British and Irish Magnetic Telegraph Company. While working in various Scottish towns he received a sound, basic training as a telegraphist.
In June 1864 James Logan sailed from Glasgow to New Zealand on the City of Dunedin, arriving at Port Chalmers on 30 September. He soon found work with a 26-man construction gang, extending the telegraph line from Dunedin to Christchurch. His genial but tough nature, together with his capacity to use his initiative and improvise quickly in remote, rugged areas, earned him the respect of the sometimes unruly linesmen. Consequently, he headed the repair gang that checked the completed line from Christchurch back to Dunedin.
Logan's leadership skills also led to his being put in charge of the erection of the Tokomairiro–Queenstown line in September 1865, at the age of 21. He immediately began experimenting with methods to overcome problems of early telegraph construction caused by the harsh winters and difficult terrain of Central Otago. These included shortening overextended wires that had sagged or broken under the weight of snow and frost, and tarring the base of wooden poles to slow the decay caused by constant thawing and freezing.
On 12 January 1866 at Dunedin James Logan married Catherine Dewar; they were to have seven daughters and four sons. By December 1869 the central government had taken control of all provincial lines and Logan transferred to the civil service as inspector of telegraphs, Dunedin. He was to hold this position for 24 years. Logan greatly improved logistics and training in the Otago telegraph service. From the mid 1860s he taught Morse code to many postmasters (or their wives) located along an advancing telegraph route. From 1870 he began replacing wooden poles with imported tubular iron. In 1879 he swiftly applied an innovation unique to New Zealand using the newly invented telephone to extend, not compete with, the telegraph; telephones offered a cheaper way of feeding messages into the telegraph system from remote areas where it was too expensive to locate a trained telegraphist. In February 1878 he initiated New Zealand's first trial of long-distance telephony, between Dunedin and Milton. Under Logan the country's first telephone office was set up early in 1879 at Portobello on Otago Peninsula; probably one of the first rural offices was established at Henley, south-west of Dunedin, in June 1881.
By the late 1880s Logan was a member of the New Zealand branch of the Institution of Electrical Engineers. In January 1894 he moved to Wellington to succeed Charles Lemon as superintendent of electric lines. Despite charges in the press that the postmaster general, Joseph Ward, had shown undue favouritism to a former colleague from the south, Logan's subsequent performance in revitalising the service after the inertia of Lemon's final years dispelled any doubts about his fitness for the job. By 1900 three new cables had been laid across Cook Strait, advanced telegraph systems such as the quadruplex (four messages along a single wire) and the Wheatstone automatic (Morse transcribed as holes on paper tape) were being introduced, and more efficient copper wiring was replacing iron. In 1902 New Zealand helped to lay the first trans-Pacific cable; by 1908 the first underground cables had reached Wellington and by 1909, Auckland.
Under James Logan telephone use was made more efficient and cheaper for households; between 1894 and 1910 the number of connections grew from 4,244 to 29,681 and exchanges increased from 24 to 153. Logan was also sufficiently far-sighted to see the advantages of wireless for telecommunications on land and sea, and he helped to draft the Wireless Telegraphy Act 1903 which eventually made radio communication a state monopoly through a network of coastal stations.
Another of Logan's legacies was the stronger emphasis placed on technical training by this self-taught, widely read man. As both inspector and superintendent, he encouraged promising staff (including a young Joseph Ward when he was working as a telegram boy in Invercargill) to better themselves, in some cases by studying engineering; he also made merit and qualifications a firm basis for promotion within the telegraph service.
Logan's efforts were acknowledged by his being appointed an ISO in 1909, and by high praise, on his retirement in February 1911, from the prime minister, Sir Joseph Ward. His wife, Catherine, died in December 1911, survived by six daughters and three sons and James died on 8 November 1912 while visiting his daughter Minnie, in Port Elizabeth, South Africa. Although buried there, he is commemorated on his wife's tombstone in Karori cemetery, Wellington.