Appointed as a teaching inspector at the École supérieure de télégraphie in 1882, he became increasingly interested in the problems of measurement in electrical circuits.

Also, after becoming head of the Bureau des Lignes, he found time for teaching other subjects outside the École Supérieure, including a course in mechanics at the Institut National Agronomique, Paris.

He remained single but shared his home with a widowed cousin of his mother and her two children whom he later adopted.

He left a formal request that no one should accompany him to the cemetery except his family and that nothing be placed on his coffin but a rose from his garden.

Thévenin is remembered as a model engineer and employee, hard-working, of scrupulous morality, strict in his principles but kind at heart.