Correct Use of Self-Grounding Outlets?

[908Jim]

Old 1940's house owner here, located in NJ and I think still on 2020 NEC, and not an electrician. Most of my home has modern NM-B but there are still 4 remaining circuits with original BX wiring. These will all be replaced over the next few years but this room needs some ugly and worn out receptacles replaced today. None of the original Appleton branded metal boxes have threaded grounding holes in them, and the outlets installed when we bought the home were three prongs just left ungrounded. In all the old single gang boxes, I used grounding clips for a ground lead but I am down to one 4x4 box with a mud ring. This means I can't slip these ground clips over the edge of the box. I have read you can drill and thread a hole but I don't know if I will get enough thread engagement and I didn't think you were allowed to modify listed boxes. These also appear to be painted black inside.

My question is: Can I use a self grounding outlet if the box is recessed past the plaster skim coat? This would mean the back of the outlet does not make contact with the metal box and the yolk mounting screw in contact with the brass self grounding spring clip thing is the only ground path back to the metal box. I was under the impression the brass was supposed to be making contact with metal but maybe I am misunderstanding the correct use. This seems better than the current state of free-floating receptacle with no ground, but I don't know if it is the correct application or if I have other options.

My other option is swapping to a GFCI/AFCI breaker I guess?

I would appreciate the help to make sure this is safe. Thank you.

 

[Firebrick43]

Self grounding outlets "MUST" have the yoke to touch the box/mud ring mounting flanges. 250.146(A), If not you need a separate bonding conductor is needed.

The mud ring/cover has to be flat as well where it mounts to the box with screws, no raised mounting areas.

You can add a ground screw as long as the box is thick enough to satisfy 250.8

"(6) Thread-forming machine screws that engage at least two threads in the enclosure"

So if the metal is 1/16th or thicker the self tapping green ground screws will work. All the old receptacle boxes I have seen usually are that thick.

Cheap metal enclosures are usually to thin to add grounding screws directly and need nuts.

 

[Chuckster in NJ]

Old 1940's house owner here, located in NJ and I think still on 2020 NEC, and not an electrician.

Good info on post #2.
FYI: NJ has adopted the the 2023 NEC on 8-17-26 and in your situation it doesn’t affect you.

 

[theoldwizard1]

My other option is swapping to a GFCI/AFCI breaker I guess?

A GFCI receptacle can be used on any old 2 wire circuit and protect the outlet. Anything downstream would also be protected.

 

[mm08822]

Self grounding outlets "MUST" have the yoke to touch the box/mud ring mounting flanges. 250.146(A), If not you need a separate bonding conductor is needed.

The mud ring/cover has to be flat as well where it mounts to the box with screws, no raised mounting areas.

You can add a ground screw as long as the box is thick enough to satisfy 250.8

"(6) Thread-forming machine screws that engage at least two threads in the enclosure"

So if the metal is 1/16th or thicker the self tapping green ground screws will work. All the old receptacle boxes I have seen usually are that thick.

Cheap metal enclosures are usually to thin to add grounding screws directly and need nuts.

Not so. The supporting screws on the receptacle (specifically the one with the spring clip) is considered making the ground connection to the metal box whether or not the receptacle ears touch the box. 250.146(B).

Non-self grounding recepts can be used with direct metal to metal contact between yoke and box/mud ring typical of surface mounted boxes/covers/mudrings. (That is what 250.146(A) states.)