Throughout his career Spagnoletti acted in various advisory roles. He was consulting engineer for a number of railway companies (Metropolitan and District, City and South London, and Central London), and also the London Electric Omnibus Company. After the Telegraph Act 1868 (which enabled the nationalisation of telegraph companies in the UK), Spagnoletti advised the government on compensation due to the companies involved. He was on the organising committee or jury, or both, for the electrical sections of various international exhibitions including the Paris World's Fair (1878), the first International Exposition of Electricity (Paris 1881), the International Health Exhibition (London, 1884), the International Inventions Exhibition (London, 1885), and the Chicago World's Fair (1893).