Ill. Admin. Code tit. 86 § 517.100
For the purposes of this Part:
"non-residential electric service" means electric utility service which is not residential electric service [305 ILCS 20/13 ];
"non-residential gas service" means gas utility service which is not residential gas service [305 ILCS 20/13 ];
"residential electric service" means electric utility service for household purposes delivered to a dwelling of 2 or fewer units which is billed under a residential rate, or electric utility service for household purposes delivered to a dwelling unit or units which is billed under a residential rate and is registered by a separate meter for each dwelling unit [305 ILCS 20/13];
"residential gas service" means gas utility service for household purposes distributed to a dwelling of 2 or fewer units which is billed under a residential rate, or gas utility service for household purposes distributed to a dwelling unit or units which is billed under a residential rate and is registered by a separate meter for each dwelling unit [305 ILCS 20/13 ].
Ill. Admin. Code tit. 86, § 517.100