Immediately after the erection of any wiring or other outdoor construction for electric light or power or before the concealment or use of any inside wiring, the person erecting the same shall notify the city electrician that such work is ready for inspection. No use shall be made of such wiring or its appurtenances for the purposes aforesaid until approved by the supervisor of public utilities and a permit therefor is issued by him. No changes in such system shall be made without a permit therefor from the supervisor of public utilities. (Code 1941, Art. 105-25)