A state agency failed to present enough evidence to justify requiring all new homes bigger than 4,500 square feet to include fire sprinklers, a Minnesota Appeals Court panel decided Tuesday. The three judges unanimously overturned the state Department of Labor and Industry's rule. "After making a careful and searching inquiry of the record, we conclude that the 4,500-square-foot threshold for one-family dwellings is arbitrary and not supported by substantial evidence in the record," the ruling said. "Based upon precedent from our Supreme Court, there must be a 'reasoned determination' as to why particular standards were chosen in an administrative rule. ... Because the record does not include evidence of any reasoned determination to indefinitely exempt new one-family dwellings under 4,500 square feet, the sprinkler rule must be declared invalid." Fire chiefs and others have lobbied the Minnesota Legislature to require sprinklers in homes, saying they can save lives. Eventually, chiefs agreed to at least require them for larger homes. When lawmakers could not pass that requirement, the Department of Labor and Industry began the process of taking action itself.