EC1GB series ground bars are intended for use in Siemens ES and PL series of load centers with a box height of 18, 21, or 23 inches. For the ES and PL lines of load centers this would include 100 and 125A load centers that are 16 1-Inch circuit spaces or less. The ground bars can be mounted in one of 4 locations inside the load center: top right, top left, bottom right, and bottom left. Up to 4 ground bars can be added to each load center. PL series load centers are already provided with 2 ground bars.