Utah Code § 54-4-19

The commissioners and officers and employees of the commission and the Department of Transportation, where public carriers are involved, shall have power to enter upon any premises occupied by any public utility for the purpose of making the examinations and tests and exercising any of the other powers provided for in this title and to set up and use on such premises any apparatus and appliances necessary therefor. The agents and employees of such public utility shall have the right to be present at the making of such examinations and tests.