Ill. Admin. Code tit. 83, § 410.320
Standard Frequency
AUTHORITY: Implementing Sections 8-301, 8-302, 8-501, 9-201, 10-101, 10-107, 16-115(d)(4) and (e)(4), 16-115A(a)(i) and (b), 16-116(b), 16-123, and 17-300(b) of the Public Utilities Act [220 ILCS 5/8-301, 8-302, 8-501, 9-201, 10-101, 10-107, 16-115(d)(4) and (e)(4), 16-115A(a)(i) and (b), 16-116(b), 16-123, and 17-300(b)].ILLINOIS COMMERCE COMMISSION
Each entity that supplies alternating current for use by retail customers in this State shall operate its equipment in a manner that the frequency of the alternating current maintained by the operation of the interconnected transmission systems is not degraded as a result of any action or lack of action on the part of the entity.