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 E — Automatic Train Stop, Train Control and Cab Signal Systems236.55149 C.F.R. § 236.551Power supply voltage; requirement.Last amended: 2017Year: 2026Length: 14 wordsOfficial source Cite as 49 C.F.R. § 236.551 (2026)The voltage of power supply shall be maintained within 10 percent of rated voltage.Previous49 C.F.R. § 236.534Next49 C.F.R. § 236.552