Basic model of a federally regulated pump

means all units of a given class of pump manufactured by one manufacturer, having the same primary energy source, and having essentially identical electrical, physical, and functional (or hydraulic) characteristics that affect energy consumption, energy efficiency, water consumption, or water efficiency; except that:

(A) for RSV and ST pumps, all variations in numbers of stages of the bare pump must be considered a single basic model;

(B) pump models for which the bare pump differs in impeller diameter, or impeller trim, may be considered a single basic model; and

(C) pump models for which the bare pump differs in number of stages or impeller diameter and which are sold with motors (or motors and controls) of varying horsepower may only be considered a single basic model if:

(1) for ESCC, ESFM, IL, and RSV pumps, each motor offered in the basic model has a nominal full load motor efficiency rated at the federal minimum (see the current table for NEMA Design B motors at Table S-1 of this Article) or the same number of bands above the federal minimum for each respective motor horsepower (see Table 3 of Appendix A to subpart Y of 10 C.F.R. part 431); or

(2) for ST pumps, each motor offered in the basic model has a full load motor efficiency at the default nominal full load submersible motor efficiency shown in Table 2 of Appendix A to subpart Y of 10 C.F.R. part 431 or the same number of bands above the default nominal full load submersible motor efficiency for each respective motor horsepower (see Table 3 of Appendix A to subpart Y of 10 C.F.R. part 431).