((a)) ** Revenue and rate of return** Nothing in this chapter shall authorize or require the recovery by an electric utility of revenues, or of a rate of return, in excess of, or less than, the amount of revenues or the rate of return determined to be lawful under any other provision of law.

((b)) ** State authority** Nothing in this chapter prohibits any State regulatory authority or nonregulated electric utility from adopting, pursuant to State law, any standard or rule affecting electric utilities which is different from any standard established by this subchapter.

((c)) ** Federal agencies** With respect to any electric utility which is a Federal agency, and with respect to the Tennessee Valley Authority when it is treated as a State regulatory authority as provided in , any reference in section 2621 or 2623 of this title to State law shall be treated as a reference to Federal law.section 2602(17) of this title