Alternatives to ground clips?

[Phil Thien]

If I have a box with no 10-32 tapped holes (for ground wires) and if I don't trust the little green clips because they fall off if I even bump them, do I have any good alternatives?

The NEC apparently says the ground screw must have three threads in contact with the box, or use the clips. Even if did drill/tap the box, I don't think I'd hit three threads because the walls are so thin (I think the boxes manufactured with the 10-32 screw holes are pierced which thickens the material in that location).

I'd sort of like to just drill the box and use a nut from the other side of the ground screw (I have access). But that three threads in contact with the box is a problem because the three threads would be in contact with the nut, not the box. And I think an inspector would point at the nut and ask "what the heck is that?"

I checked the boxes at HD and Ace and their octagonal ceiling boxes also have no threaded holes for ground wires.

[Joe Watson]

Just finished my final electrical inspection two weeks ago on an addition im adding to my home. The inspector was great and had no problems with me giving him a buzz with questions, maybe the same will work for you.

One thing that popped into my head while reading your post, if you do not use a lock-washer there is a (slim) chance the nut will come loss (and you will have the ground wire loose in the box with an easy chance to short-out), and if you do use a lock washer it will kill your "metal-to-metal" contact (not sure what the three thread reason is, for strength or for contact). Maybe a nut with a nylon lock built into it would be something to look into.


Im no electrician by trade, so... good luck.

_

[glenn bradley]

Machine screw, start washers and nut.

[Phil Thien]

I should have just read the NEC (which I have at work but not home, I'll have to toss the PDF on my thumb drive). I can do #5 with the nut (my preferred method). I'd use a self-tapper but I'm going into the side of the box that is in an awkward location. I can get adequate torque with a nut, probably not a self-tapper.


*****

2008 NEC

250.8 Connection of Grounding and Bonding

Equipment.

(A) Permitted Methods. Grounding conductors and bonding jumpers shall be connected by one of the following means:

(1) Listed pressure connectors

(2) Terminal bars
(3) Pressure connectors listed as grounding and bonding equipment
(4) Exothermic welding process
(5) Machine screw-type fasteners that engage not less than two threads or are secured with a nut
(6) Thread-forming machine screws that engage not less than two threads in the enclosure
(7) Connections that are part of a listed assembly
(8) Other listed means

(B) Methods Not Permitted. Connection devices or fittings that depend solely on solder shall not be used.

[Phil Thien]

Machine screw, start washers and nut.

Ayep. Thank you!

[Rick Christopherson]

Use one of these self grounding outlets and you don't have to add the strap to the box. Note the brass tab on the lower yoke.

[Thom Sturgill]

Put a little lock-tight on the nut if you are worried about it coming loose.

[Phil Thien]

Use one of these self grounding outlets and you don't have to add the strap to the box. Note the brass tab on the lower yoke.

My specific problem was transitioning from a conduit-fed (no separate ground wire) box without a 10-32 hole, to 14-2 MC.

I had thought the green clips are supposed to be made of spring steel, but the two different brands I've tried sure aren't. They take a shape very easily. I think if they were actually spring steel they'd work fine for me.