Avian electrocutions on power poles (hereafter, poles) are a global conservation concern, particularly for large-bodied species like Golden Eagles (Aquila chrysaetos). Retrofitting poles through increasing clearances (separation) between components, adding insulation to components, or adding redirection materials like perch discouragers reduces risk, but electrocutions may occur even on retrofitted poles. We evaluated 52 retrofitted poles where 56 birds, including 17 Golden Eagles, were electrocuted after retrofitting. We used burns on pole equipment and carcasses to identify precise pole-top locations where electrocutions occurred, and we identified three categories of retrofitting errors: product design, mitigation plan, and application. Product design errors (n = 9 poles, 6 Golden Eagles) occurred when products did not sufficiently cover energized equipment. Mitigation plan errors (n = 30 poles, 6 Golden Eagles) occurred when retrofitting plans did not include coverage of all energized components on a pole. Application errors (n = 13 poles, 5 Golden Eagles) occurred when the correct products were installed incorrectly. Retrofitting mistakes were identified in this study retroactively when avian electrocutions occurred on poles described as retrofitted. This is typical of how retrofitting mistakes are identified by the electric industry, which can lead to expensive duplicate efforts, and ongoing avian electrocutions. These can be avoided if retrofitting is done correctly initially. This study provides insight to electric utility personnel and wildlife managers interested in proactively evaluating the thoroughness of retrofitting, facilitating immediate identification and correction of retrofitting errors, increasing cost effectiveness, and reducing avian electrocution mortality.