This chapter shall apply to every certificated water or sewer public utility company or water and sewer public utility company (i) with gross annual operating revenues of less than one million dollars or (ii) that is owned by the property owners’ association of the subdivision served by the public utility. In case of a company with gross annual revenues of $500,000 or more, (i) the Commission may suspend a proposed increase in rates for a period not exceeding 150 days from the date of the filing of the proposed rate increase and (ii) notwithstanding any other provision of this chapter, such company shall be subject to Chapter 4 (§ 56-76 et seq.) of Title 56.