Q. Can I use 12-3 NM cable to wire the bathroom GFCIs and laundry circuit in a dwelling?
A. Sure, if you use a GFCI receptacle for the first outlet for the bathroom receptacle circuit, and all down-stream receptacles are supplied through the GFCI receptacle.
Be aware that the continuity of the grounded (neutral) conductor of a multiwire branch circuit (before the GFCI receptacle) must not be interrupted by the removal of a wiring device. Therefore, the grounded (neutral) conductors before the GFCI receptacle must be spliced together, and a pigtail must be provided for the wiring device [300.13(B)].
About the Author
Mike Holt
Mike Holt is the owner of Mike Holt Enterprises (www.MikeHolt.com), one of the largest electrical publishers in the United States. He earned a master's degree in the Business Administration Program (MBA) from the University of Miami. He earned his reputation as a National Electrical Code (NEC) expert by working his way up through the electrical trade. Formally a construction editor for two different trade publications, Mike started his career as an apprentice electrician and eventually became a master electrician, an electrical inspector, a contractor, and an educator. Mike has taught more than 1,000 classes on 30 different electrical-related subjects — ranging from alarm installations to exam preparation and voltage drop calculations. He continues to produce seminars, videos, books, and online training for the trade as well as contribute monthly Code content to EC&M magazine.