I would like to run NM wire in a short section of metallic conduit (e.g. EMT) perpendicular to the joists in my basement so I do not have to drill any additional holes in the joists as allowed by 334.15(C) of the NEC.

As I understand section 334.15(C) of the NEC, I will still have to bond the EMT to keep it from becoming energized in case of a ground fault if I use a short section of to provide support and protection of the NM cable from physical damage per 300.12. The code provides specific guidance in 334.15(C) on how to do this, but provides very little information on how to properly ground it.

Can I properly ground the EMT without adding a junction box on one end or the other of the EMT just to splice the NM inside of the junction box and access the ground wire? If so, what are the methods to do so? At this point, I'm thinking Schedule 80 PVC is the easier way to go to avoid needing bond the conduit, but I'm still curious how this is done in practice (that is, if it is done).

Note: The NM cable is smaller than three 8 AWG conductors, so I cannot staple the cable to the bottom of the joists directly per 334.15(C) of the NEC.

Relevant quoted sections of the NEC (NFPA-70:2014)

334.15(C) In Unfinished Basements and Crawl Spaces. Where cable is run at angles with joists in unfinished basements and crawl spaces, it shall be permissible to secure cables not smaller than two 6 AWG or three 8 AWG conductors directly to the lower edges of the joists. Smaller cables shall be run either through bored holes in joists or on running boards. Nonmetallic-sheathed cable installed on the wall of an unfinished basement shall be permitted to be installed in a listed conduit or tubing or shall be protected in accordance with 300.4. Conduit or tubing shall be provided with a suitable insulating bushing or adapter at the point the cable enters the raceway. The sheath of the nonmetallic-sheathed cable shall extend through the conduit or tubing and into the outlet or device box not less than 6 mm (1⁄4 in.). The cable shall be secured within 300 mm (12 in.) of the point where the cable enters the conduit or tubing. Metal conduit, tubing, and metal outlet boxes shall be connected to an equipment grounding conductor complying with the provisions of 250.86 and 250.148.

300.12 Mechanical Continuity — Raceways and Cables. Metal or nonmetallic raceways, cable armors, and cable sheaths shall be continuous between cabinets, boxes, fittings, or other enclosures or outlets. Exception No. 1: Short sections of raceways used to provide support or protection of cable assemblies from physical damage shall not be required to be mechanically continuous.

2 Answers 2


You don't have to bond the conduit if it's only there to "provide support or protection of cable assemblies from physical damage", according to 250.86 ex. 2.

National Electrical Code 2014

Chapter 2 Wiring and Protection

Article 250 Grounding and Bonding

250.86 Other Conductor Enclosures and Raceways. Except as permitted by 250.112(I), metal enclosures and raceways for other than service conductors shall be connected to the equipment grounding conductor.

Exception No. 2: Short sections of metal enclosures or raceways used to provide support or protection of cable assemblies from physical damage shall not be required to be connected to the equipment grounding conductor.


Exception 1 would be where you look. It clearly addresses nm cable. Cable assemblies refer to pre-assembled cable runs such as for mini splits etc. So 250.86 exc. 1 Metal enclosures and raceways for conductors added to existing installations of open wire, knob and tube wiring, and nonmetallic-sheathed cable shall not be required to be connected to the equipment grounding conductor where these enclosures or wiring methods comply with (1) through (4). 1 do not provide an equipment ground 2 are in runs of less than 7.5 m (25 feet) 3 are free from probable contact with ground, grounded metal, metal lath, or other conductive materials 4 are guarded against contact by persons

  • Wrong -- NM cables are just as much "cable assemblies" as something prefabricated is Jan 7, 2023 at 5:29

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