NEC 250.148(b) vs. Luminaire Grounding

Question

I'm always trying to learn more and improve my methods for home wiring.

Most examples I see regarding 250.148(b) simply illustrate use of a pigtail and wire nut.

(B) Equipment Grounding Conductor Continuity. The arrangement of grounding connections shall be such that the disconnection or the removal of a luminaire, receptacle, or other device fed from the box does not interrupt the electrical continuity of the equipment grounding conductor(s) providing an effective ground-fault current path.

So consider the scenario where the EGC pigtail is not simply connected to a device grounding screw. On many luminaires, there is a grounding wire riveted to the conducting exterior parts. If I bring that luminaire grounding wire into a wire nut with the circuit EGC(s) from the box, then the luminaire will be grounded. But if I need to remove the luminaire, common sense says I would have to remove the wire nut thus violating NEC 250.148(b).

Does this mean I should use two wire nuts, and splice the luminaire grounding wire to a pigtail, then splice the pigtail with the circuit EGC(s)? If so, is this the literal intent of NEC 250.148(b)?

If that's not correct, then what is the actual requirement under 250.148(b) for outlets that do not have a grounding screw?

Let's assume this luminaire is attached to a box with more than one NM cable and more than one EGC.

Answer 1

A pigtail to a second connection is one approach that you can use to meet this requirement. Another possible approach is to crimp the ground connectors together and attach the luminaire to the portion of conductor past the crimp. Or you can use those green wire nuts that have a hole down the middle to allow you to pass a ground wire through the connection. If the box is metal, you can ground the fixture to the box and tie the grounds to the box with a different screw. There are lots of approaches available here. To remain compliant just make certain that if you remove the fixture and stop doing work as soon as the three wires are disconnected, the ground connection remains continuous.

Answer 2

I agree with your assessment. Your goal of achieving it in one splice does not appear to be attainable. However wire nuts cost a nickel.

Metal boxes

Note with a metal box, Code requires grounds from cables go to the metal box first. From that point, most devices will pick up ground via their mounting screws. (luminaires, switches, and "receptacles which are labeled Self-Grounding, or have hard flush yoke-box contact"). In most cases that means you are done and the ground pigtail need not be addressed.

Can lights with integral junction boxes

The starting point is the UL Listing. If it is not UL, CSA, ETL or other NRTL, then back to the store it goes. If it is, then you need to follow the instructions which UL etc. approved when approving the equipment. If they are not specific about multiple cables into the box, then you need to follow the NEC box fill rules. Presuming all that is in order...

That thing you are splicing inside is a junction box. You may have bought it as part of a luminaire, but since you attaching multiple cables to it in an approved way, the box is functioning as a junction box and follows those rules. Obviously NEC permits replacement of junction boxes, including breaking apart the grounds of all the cables entering the box.

By the way, this is done all the time with fluorescent fixtures.