Boulder officials on Tuesday took a major step in their years-long effort to create a new city-owned utility by formally asking the Colorado Public Utilities Commission to approve the transfer to the city equipment and assets owned by Xcel Energy Inc. The city's 333-page request sought to avoid one area of contention by pointedly noting that the city only wants assets and equipment needed to serve Boulder customers. Some equipment Boulder previously indicated it wanted was controversial because Xcel uses it to serve customers inside and outside the city limits.