# 60.4405a How do I conduct a performance test if I use a NO CEMS?
(a) If you use a CEMS the performance test must be performed according to the procedures specified in paragraph (b) of this section.
(b) The initial performance test must use the procedure specified in paragraphs (b)(1) through (4) of this section.
(1) Perform a minimum of nine RATA reference method runs, with a minimum time per run of 21 minutes, at a single load level, within ±25 percent of 100 percent of the base load rating while the source is combusting the fuel that is a normal primary fuel for that source. You may perform testing at the highest achievable load point, if at least 75 percent of the base load rating cannot be achieved in practice. The ambient temperature must be greater than 0 °F during the RATA runs. The Administrator or delegated authority may approve performance testing below 0 °F if the timing of the required performance test and environmental conditions make it impractical to test at ambient conditions greater than 0 °F.
(2) For each RATA run, concurrently measure the heat input to the unit using a fuel flow meter (or flow meters) or the methodologies in appendix F to part 75 of this chapter, and for units complying with the output-based standard, measure the electrical and thermal output from the unit.
(3) Use the test data both to demonstrate compliance with the applicable NO<sub>X</sub> emissions standard under § 60.4320a and to provide the required reference method data for the RATA of the CEMS described under § 60.4342a.
(4) Compliance with the applicable emissions standard in § 60.4320a is achieved if the sum of the NO<sub>X</sub> emissions divided by the heat input (or gross or net energy output) for all the RATA runs, expressed in units of lb/MMBtu, ppm, lb/MWh, or kgs, does not exceed the emissions standard.