A modular, space-efficient support structure mounts multiple electrical devices. The structure is modular to allow for subsequent addition and removal of electrical devices by adding and removing primary structural elements coupled for structural efficiency. The structure is deployable in many locations without reconfiguration and has reduced dependence on local site conditions. The structure uses non-permanent construction methods to facilitate rapid assembly, disassembly, re-deployment and re-use of components. Multiple electrical devices such as transformers are mounted at elevation on device mounting columns. The electrical devices are interconnected to each other in parallel or series with connectors mounted on the top portion of the device to allow maintenance clearance underneath. The arrangement of the electrical devices maximizes the density of the devices while maintaining vertical, lateral and radial safety clearances. The electrical devices are arranged in a symmetrical fashion around the primary structural element for symmetrical load distribution.