An FS box holder for mounting a field service (FS) electrical box to a cylindrical structure. The FS box holder includes a front panel and two end walls and two side walls extending from the front panel. Elongated slots are provided in the side walls and a threaded nipple extends from the front panel. A post attachment means is provided for securing said FS box holder to a post or similar upright support. The post attachment means includes a pipe clamp for securing through the elongated slots of the FS box holder. The invention further includes an electrical box having a threaded socket therein and a box attachment means for securing the electrical box to the FS box holder. The box attachment means includes a threaded socket on the electrical box and a threaded nipple on the FS box holder.