49 C.F.R. § 236.720 Circuit, common return.
Title 49 - Transportation
A term applied where one wire is used for the return of more than one electric circuit.
Title 49: Transportation
PART 236—RULES, STANDARDS, AND INSTRUCTIONS GOVERNING THE INSTALLATION, INSPECTION, MAINTENANCE, AND REPAIR OF SIGNAL AND TRAIN CONTROL SYSTEMS, DEVICES, AND APPLIANCES
Subpart G—Definitions
§ 236.720 Circuit, common return.