R8‑16     STANDARD FREQUENCY

Each utility supplying alternating current shall adopt a standard frequency, the suitability of which may be determined by the Commission, and shall maintain this frequency within 2% plus or minus of standard at all times during which service is supplied; provided, however, the momentary variations of frequency of more than 5%, which are clearly due to no lack of proper equipment or reasonable care on the part of the utility, shall not be construed as a violation of this rule.