A four family dwelling unit has a heating and airconditioning unit installed on a roof. For servicing of the unit, a 125 volt receptical is required on the same level at a maximum of ____ feet from the unit.

A four family dwelling unit has a heating and airconditioning unit installed on a roof. For servicing of the unit, a 125 volt receptical is required on the same level at a maximum of ____ feet from the unit.