US lawFederal (United States)RegulationsTitle 49 CFR — TransportationChapter II — FEDERAL RAILROAD ADMINISTRATION, DEPARTMENT OF TRANSPORTATIONPart 236 — RULES, STANDARDS, AND INSTRUCTIONS GOVERNING THE INSTALLATION, INSPECTION, MAINTENANCE, AND REPAIR OF SIGNAL AND TRAIN CONTROL SYSTEMS, DEVICES, AND APPLIANCESSubpart G — Definitions236.72049 C.F.R. § 236.720Circuit, common return.Last amended: 2017Year: 2026Length: 17 wordsOfficial source Cite as 49 C.F.R. § 236.720 (2026)A term applied where one wire is used for the return of more than one electric circuit.Previous49 C.F.R. § 236.719Next49 C.F.R. § 236.721