26 Del. C. § 304

(a) Unless the Commission otherwise orders, no public utility shall make any change in any existing rate except after 60 days notice to the Commission, which notice shall plainly state the changes proposed to be made in the rates then in force and the time when the changes will go into effect. All proposed changes shall be shown by filing new schedules or shall be plainly indicated upon schedules filed and in force at the time and kept open to public inspection. Public notice of all proposed changes shall be given in a form and manner set by the Commission. The Commission, for good cause shown, may allow changes in rates without requiring the 60-days’ notice and/or public notice under such conditions as it may prescribe. All such changes shall be immediately indicated upon its schedules by such public utility.

(b) In prescribing conditions for rate changes, the Commission is specifically authorized and empowered to conduct proceedings in which it limits the number or type of issues it will consider in determining whether or not to permit or allow such changes. The Commission may adopt or change regulations to govern such limited issue rate proceedings.