Abstract: The present disclosure includes an electric-box-assembly mountable on a first wall of a double wall structure for use in conjunction with the second wall of the double wall structure, a method of mounting the electric-box-assembly and wiring of the same. The electric-box-assembly includes a mounting-bracket including one or more mounting units, wherein each of said mounting units comprises a mounting panel; and an electric box. The mounting panel is configured to be directly attached onto the inner side of the first wall of the double wall structure, adjacently thereto, the first wall being erected. The electric box is configured to be mounted onto the inner side of the first wall of the double wall structure before the second wall of the double wall structure is securely attached to the beam-infrastructure.