He then acted for a time as Consulting Engineer for electric lighting to the Northern London Estates Company, and in 1884 he joined Thomas Parker in partnership on the formation of the undertaking at Wolverhampton known as Elwell-Parker, Limited.

For the next three years he was engaged in that capacity in the design and manufacture of all kinds of heavy electrical machinery for tramways, lighting, mining, the deposition of metals, and other purposes.

From 1887 to 1889 he practised as a Consulting Engineer, preparing plans, in conjunction with Messrs. Berlier, for the proposed underground tubular electric railway in Paris, and carrying out experiments with Messrs. Commelin and Desmoyhres in connection with submarine boats. While in Paris he translated into English Gaston Plante's 'Recherches sur l’Electricite.'

In 1889 Mr. Elwell went to New South Wales and practised for a time as a Consulting Engineer in Sydney. His ability and experience soon attracted attention, and in 1891 he was appointed Electrical Engineer to the Railway Commissioners of the Colony. In that capacity Mr. Elwell rendered valuable service to the Railway Department. Under the direction of the Commissioners the electric train staff and tablet system of safe railway working was extended to cover practically all the busy portions of the line, being in operation in the north as far as Tamworth, in the west to Dubbo, and in the south to Albury: and during the installation of the electric instruments for the safe working of the lines numerous improvements were devised, largely by Mr. Elwell, in order to meet special traffic requirements on particular sections.

In 1895, at the instance of the Commissioners, he studied in America and on the Continent the latest devlopments in connection with electric tramway working; and the experience thus obtained, coupled with his wide technical knowledge, enabled him to render great assistance to Mr. Henry Deane, the Engineer-in-Chief of the Railway Department, in the construction of electric tramways in New South Wales and in the conversion of the present steam system into electric traction. The last and most important work on which he was engaged was the George and Harris Streets Tramway, with its large power station containing four generators of 850 kilowatts each.

Unfortunately Mr. Elwell did not live to see the completion of this work. He was found to be suffering from some disease which attacked the ankle, and, in the hope of entire eradication, the leg was removed above the knee. The operation did not have the desired effect, and the disease, spreading further, caused his death on the 10th September, 1899.