All-purpose outlet box. 4 in. x 2 1/8 in. x 1 7/8 in. Made of galvanized steel. Utility boxes are specially designed for surface mounted installation of a single device when used with proper cover. They are mainly used with EMT, but can also be used with BX or Loomex, using proper connectors. In such cases, the cable must be located and protected to avoid possible mechanical injury.