# ground screws



## Bob Badger

John Rutter said:


> I know that on a device (recep, switch) or in a panel for bonding, the ground screw has to be green, but does that include 4 squares boxes pig tails (code ref please).


There is no code to give you, the NEC does not say 'ground screws do not have to be green' the NEC just never requires box grounding screws to be green 




> Also can you use a self tapper as ground screw and if not code ref.
> thanks


Yes if it has machine threads, see 250.8


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## Rockyd

250.148 was the best I could come up with.


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## Adam12

Legally you can use anything but a sheet metal screw according to the 05.... drywall or wood screw included. 250.8
Not recommended though and will likely cause an arguement here. :jester:


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## kancerr

use whatever you want, i would avoid coated screws...best advice i can give you, use whatever ya got long as it threads and holds okay, check to make sure you have a good ground when youre done.


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## BuzzKill

kancerr said:


> use whatever you want, i would avoid coated screws...best advice i can give you, use whatever ya got long as it threads and holds okay, check to make sure you have a good ground when youre done.


yeah really, use whatever.


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## John Valdes

250-148(C) Metal Boxes
The screw must be listed for the purpose. Or other listed grounding devices can be used. 
Not color specific and no mention of threads either.


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## Bob Badger

John Valdes said:


> 250-148(C) Metal Boxes
> The screw must be listed for the purpose.


There is no such thing as a listed grounding screw.

The NEC does not require one.


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## Toronto Sparky

Bob Badger said:


> There is no such thing as a listed grounding screw.
> 
> The NEC does not require one.


Thats why I use the plastic ones.. And they don't rust!


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## jwjrw

Bob Badger said:


> There is no code to give you, the NEC does not say 'ground screws do not have to be green' the NEC just never requires box grounding screws to be green
> 
> Yes if it has machine threads, see 250.8


 
Oh no not another box grounding thread. Maybe this one won't turn into "my way is common sense and just as good" like the last one did.
Bob is correct and remember he backed it up with the NEC not an inflated ego about how (someone) knows better than the code and you are blah blah blah..:whistling2::laughing::laughing:


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## 220/221

:sleeping::sleeping::sleeping:


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## BuzzKill

jwjrw said:


> Oh no not another box grounding thread. Maybe this one won't turn into "my way is common sense and just as good" like the last one did.
> Bob is correct and remember he backed it up with the NEC not an inflated ego about how (someone) knows better than the code and you are blah blah blah..:whistling2::laughing::laughing:


Raider1 is around I say let him chime in; he's another NEC guru.


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## raider1

BuzzKill said:


> Raider1 is around I say let him chime in; he's another NEC guru.


Thanks.:thumbsup:

250.8 tells use what type of screw must be used to connect grounding and bonding equipment. There is no requirement that this screw be green.



John Valdes said:


> 250-148(C) Metal Boxes
> The screw must be listed for the purpose. Or other listed grounding devices can be used.
> Not color specific and no mention of threads either.


250.148 does not say that the screw must be listed for the purpose.

Here is what 250.148 says;



> 250.148 Continuity and Attachment of Equipment Grounding Conductors to Boxes.
> (C) Metal Boxes. A connection shall be made between the one or more equipment grounding conductors and a metal box by means of a grounding screw that shall be used for no other purpose, equipment listed for grounding, or a listed grounding device.


Chris


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## beasley

*Reponse*



Bob Badger said:


> There is no code to give you, the NEC does not say 'ground screws do not have to be green' the NEC just never requires box grounding screws to be green
> 
> 
> 
> 
> Yes if it has machine threads, see 250.8


If it is a self tapping screw has machine treads it is created by the screw (not normally machine threaded). Threaded grounding screw holes are provided in a 4" sq (1900 box & all other metallic boxes) and are pre-threaded, so whats the the need for a self tapping screw?


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## Toronto Sparky

8-32 / 10-32 provides much more contact then a self tapping screw..


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## 220/221

beasley said:


> Threaded grounding screw holes are provided in a 4" sq (1900 box & all other metallic boxes) and are pre-threaded, so whats the the need for a self tapping screw?


 
Occaisionally during remodel work, you will run into boxes that do not have a ground hole tapped. The same is true of some larger enclosures.



> 8-32 / 10-32 provides much more contact then a self tapping screw..


That's debatable.


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## VersaJoe

I carry a few of those greenleee 10/32 drill tap bits for when I encounter an older box with no ground screw hole. I drill and tap and the same time then just use one of the screws. I know green ones are not required but I just like to use them.


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## Rockyd

Anybody remember where I saw the verbiage that grounding was attained by 2 threads in contact with metal surface? Can't remember if it was UL language, a seminar, or a BS session. Would like to know if it is UL approved? Believe the other half of the conversation was that if you can't get two threads, drill it, and through bolt it for a solid ground connection.


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## VersaJoe

These look cool too but they arent machine threads....


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## Adam12

If it's a sheet metal screw it's not allowed, anything but a sheet metal screw would be technically legal. A drywall screw, wood screw or any machine screw would be ok.

Anyone that would actually use a drywall or wood screw should be shot on site.


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## VersaJoe

Don't sheet metal screws and drywall screws have the same kind of threads?


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## Ocularpatdown

VersaJoe said:


> Don't sheet metal screws and drywall screws have the same kind of threads?


Yes, Adam's post is completely screwed up. He goes from saying that drywall and wood screws are ok, to saying that using drywall and wood screws is wrong and should get you shot.


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## Rudeboy

Ocularpatdown said:


> Yes, Adam's post is completely screwed up. He goes from saying that drywall and wood screws are ok, to saying that using drywall and wood screws is wrong and should get you shot.


:laughing:

I dunno, i always use "ground" screws every time I ground wire in a box. What's the big deal?


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## Ocularpatdown

Rudeboy said:


> :laughing:
> 
> I dunno, i always use "ground" screws every time I ground wire in a box. What's the big deal?


Not all old existing boxes have 10/32 holes in them, or sometimes they have the hole but it isn't bumped forward so you can't thread the screw in the hole because the screw is bottoming out into the wall behind the box, etc.

What I found is that most older boxes use a 10/32 tapped hole for the clamp screws so if you remove an unneeded clamp you can put a ground screw there.


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## Adam12

Ocularpatdown said:


> Yes, Adam's post is completely screwed up. He goes from saying that drywall and wood screws are ok, to saying that using drywall and wood screws is wrong and should get you shot.


 
Your interpretation of my post is screwed up. 

Never said it was ok, just the fact that it would be legal.


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## Ocularpatdown

Adam12 said:


> Your interpretation of my post is screwed up.
> 
> Never said it was ok, just the fact that it would be legal.


Are you sure? You could use drywall screws knowing that their threads are not fine enough to have at least 2 threads contact the box?


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## Rudeboy

Ocularpatdown said:


> Not all old existing boxes have 10/32 holes in them, or sometimes they have the hole but it isn't bumped forward so you can't thread the screw in the hole because the screw is bottoming out into the wall behind the box, etc.
> 
> What I found is that most older boxes use a 10/32 tapped hole for the clamp screws so if you remove an unneeded clamp you can put a ground screw there.


When I encounter those types of boxes like I did today, I just drill a little hole and tap it to 10. Takes about ten or fifteen minutes if I take a long break right after I make the hole.
:whistling2:


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## Adam12

Ocularpatdown said:


> Are you sure? You could use drywall screws knowing that their threads are not fine enough to have at least 2 threads contact the box?


How do you know they aren't fine enough?

Most importantly it depends on what year code you currently work under.......


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## Ocularpatdown

Rudeboy said:


> When I encounter those types of boxes like I did today, I just drill a little hole and tap it to 10. Takes about ten or fifteen minutes if I take a long break right after I make the hole.
> :whistling2:


That's a lot of work, I usually just fold the grounds back into the box so that they are touching the side. Sometimes I'll put one of the ground wires under the cover plate and tighten it down, when I feel that grounding is important in that situation (very rarely).


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## Rudeboy

Ocularpatdown said:


> That's a lot of work, I usually just fold the grounds back into the box so that they are touching the side. Sometimes I'll put one of the ground wires under the cover plate and tighten it down, when I feel that grounding is important in that situation (very rarely).


Well you could just splice the neutral and get your ground there.


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## Ocularpatdown

Rudeboy said:


> Well you could just splice the neutral and get your ground there.


Not with those pesky AFCIs :no:


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## Rudeboy

Ocularpatdown said:


> Not with those pesky AFCIs :no:


Oh yeah, they are pita.


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## ohmega

:Quote: Believe the other half of the conversation was that if you can't get two threads, drill it, and through bolt it for a solid ground connection.




A through bolt? 


How do you bolt it to the back side?


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## Toronto Sparky

Drywall screw? With counter sunk head?
They also tend tend to rust.. 
No drywall screws for me...


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## Toronto Sparky

ohmega said:


> :Quote: Believe the other half of the conversation was that if you can't get two threads, drill it, and through bolt it for a solid ground connection.
> 
> 
> 
> 
> A through bolt?
> 
> 
> How do you bolt it to the back side?


A nut on the other side of the wall... :clap:

Just paint it out.. No one will see..


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## jwjrw

Rudeboy said:


> When I encounter those types of boxes like I did today, I just drill a little hole and tap it to 10. Takes about ten or fifteen minutes if I take a long break right after I make the hole.
> :whistling2:


 
Get a greenlee drill/tap. Keep it in your nail apron and in 15 seconds you have a tapped hole for your ground screw.


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## ohmega

Toronto Sparky said:


> A nut on the other side of the wall... :clap:
> 
> Just paint it out.. No one will see..





You'd have to be a NUT to do that! :blink: And I sure as hell dont carry paint on the rig...... hmmmmm now is that navajo white or an eggshell???? If I did I would be disscussing this on the painters talk forum on how to touch-up electricians hack jobs!!  But If I did carry paint I would paint every one of my ground screws the purdiest shades of green.... drywall or machine.. dont matter!


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## randomkiller

Rudeboy said:


> :laughing:
> 
> I dunno, i always use "ground" screws every time I ground wire in a box. What's the big deal?


 
Agreed, they come in those nice little plastic containers that fit in a shirt pocket or apron, and there is no screwing around (pardon the pun).


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## Rockyd

To stir the pot, check out 250.126. Just sayin


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## raider1

Rockyd said:


> To stir the pot, check out 250.126. Just sayin


That section only applys to device terminals not to the ground screw used to connect the EGC to a box.

Chris


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## Conduit Phil

Rockyd said:


> Anybody remember where I saw the verbiage that grounding was attained by 2 threads in contact with metal surface? Can't remember if it was UL language, a seminar, or a BS session. Would like to know if it is UL approved? Believe the other half of the conversation was that if you can't get two threads, drill it, and through bolt it for a solid ground connection.


I've heard of this before as well although I don't know if theres any basis for it. A typical steel box is 1/16" thick sheet metal. A 10-32 screw in 1/16" steel would give you 2 threads engaged. What if you tap a hole in an enclosure thats less than 1/16" thick?


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## 480sparky

Conduit Phil said:


> I've heard of this before as well although I don't know if theres any basis for it. A typical steel box is 1/16" thick sheet metal. A 10-32 screw in 1/16" steel would give you 2 threads engaged. What if you tap a hole in an enclosure thats less than 1/16" thick?



Then a sharp inspector will call you on 314.40(B).


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## Rudeboy

jwjrw said:


> Get a greenlee drill/tap. Keep it in your nail apron and in 15 seconds you have a tapped hole for your ground screw.


Yeah, I've been meaning to get one but I keep forgetting. I'm just using a 6n1 for the time being.


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## randomkiller

Rudeboy said:


> Yeah, I've been meaning to get one but I keep forgetting. I'm just using a 6n1 for the time being.


 
The ground screws we get are self tapping threads, they work well on all but the thickest of boxes.


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## Rockyd

Ohmega, TorontoSparky, Conduit Phil, 480Sparky



Rockyd said:


> Anybody remember where I saw the verbiage that grounding was attained by 2 threads in contact with metal surface? Can't remember if it was UL language, a seminar, or a BS session. Would like to know if it is UL approved? Believe the other half of the conversation was that if you can't get two threads, drill it, and through bolt it for a solid ground connection.


 
Found it (doing something not even related, but "debating another issue)

See 250.8(A)(5) and (6).


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## beasley

220/221 said:


> Occasionally during remodel work, you will run into boxes that do not have a ground hole tapped. The same is true of some larger enclosures.
> 
> That's debatable.


 Not Really: Never saw a 1900 or orher standard device box without a pre-threaded 10-24 screw. If you have one that is not pre-threaded, drill a hole in the box & tap the hole yourself. True, that they do not have to be green & not NEC mandated, but devices must have green screws on them. Larger pull boxes may not have a tapped hole, but there is a siimple solutions these circumstances.


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## swimmer

I knew there was a hex-head requirement in there somewhere
They need to integrate 250.8 and 250.126

*250.126 Identification of Wiring Device Terminals.* The terminal for the connection of the equipment grounding conductor shall be identified by one of the following:
(1) A *green*, not readily removable terminal screw with a *hexagonal* head.
(2) *green*, *hexagonal* not readily removable terminal nut.
(3) A green pressure wire connector. If the terminal for the grounding conductor is not visible, the conductor entrance hole shall be marked with the word green or ground, the letters G or GR, a grounding symbol, or otherwise indentified by a distinctive green color. If the terminal for the equipment grounding conductor is readily removable, the area adjacent to the terminal shall be similarly marked.


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## Deep Cover

250.126 is for *device terminals*.....and this thread is 3 years old


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## don_resqcapt19

Adam12 said:


> If it's a sheet metal screw it's not allowed, anything but a sheet metal screw would be technically legal. A drywall screw, wood screw or any machine screw would be ok.
> ...


Starting with the 2008 code that statement is not correct.


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## jimk7525

250.126(1)(2)(3)?


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## wendon

Rockyd said:


> To stir the pot, check out 250.126. Just sayin


To further stir the pot what about 250.28 (B)
If you install ground bars in your Main panel for the grounding conductors, and the screws aren't green, is that a code violation?


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## swimmer

Deep Cover said:


> .....and this thread is 3 years old


I like to keep it all in one place


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## Fibes

wendon said:


> To further stir the pot what about 250.28 (B)
> If you install ground bars in your Main panel for the grounding conductors, and the screws aren't green, is that a code violation?


No, only the screw that is the "Main Bonding Jumper" is required to be green, the terminal screws are not.


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## Magoo5150

Rockyd said:


> Anybody remember where I saw the verbiage that grounding was attained by 2 threads in contact with metal surface? Can't remember if it was UL language, a seminar, or a BS session. Would like to know if it is UL approved? Believe the other half of the conversation was that if you can't get two threads, drill it, and through bolt it for a solid ground connection.


 
250.8(5) Machine screw type fasteners that engage not less than two threads or are secured with a nut.


If you use an ?-32 screw in a standard 1/16" thick box, this will give you the two threads engaged as required.


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## Mshea

Magoo5150 said:


> 250.8(5) Machine screw type fasteners that engage not less than two threads or are secured with a nut.
> 
> 
> If you use an ?-32 screw in a standard 1/16" thick box, this will give you the two threads engaged as required.


 
Magoo gets the prize.
In Canada this does not appear as a rule in the installation code but a rule in the Product Standards. For the minimum thickness permitted for electrical enclosures a screw with at least 32 threads per inch will engage 2 full threads. any screw with less threads per inch like a 10-24 would require the box to be thicker than 10MSG (1/16") thicker metal would also eliminate sheet metal screws as the threads would require a cut in groove. IE machine screw and tapped.
This is a harmonized requirment and should apply to Mexico as well.


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## Toronto Sparky

I have more concern about all these big, heavy, shaking, and wobbling Ceiling fans being held up with two 8-32 screws.. And the safety cable is quite often just tied under the ground screw..


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