A few weeks ago I was lucky enough to score a nice early Square D Co. catalog at a resonable price. I've been trying to find one to not only see there safety boxes but the porcelain insulators made. Square D Co. made porcelain insulators from 1920 t0 1951 for themselves and under contract for other companies. Little is known of how many styles they had and these pages confirm some of them and new discoveries. The pages are from a 1928 Safety Switches and Power Pannels catalog. This first page shows five different strains produced for themselves catalog numbers 5500 thru 5508.