Self grounding outlet with screws only

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huma

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Hi!

I've heard before that mounting screws are not an accepted grounding for a self grounding outlet and a grounding clip should be used, I assume the code probably says the same (I'm in NJ, USA for that matter).

I'm curious why the screws are not an acceptable ground path, is it because they are too "weak" ground conductor for high load or because they are unreliable ground conductor as they can move or something like that?

If they're considered as a too "weak" ground, then why mounting screws are an accepted self ground for light switches though?
 

Snoonyb

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I've never heard of a "self grounding" recep. or switch, because for there to be a path to ground, there must exist a mechanical connection, too ground, and that occurs in several different mechanisms, depending upon how a circuit is connected.
 

afjes_2016

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Huma

Look at the receptacle (outlet) below. The bottom part of the strap (ears) has that extra piece of metal on it which makes a more secure connection to the rest of the metal on the receptacle to complete the grounding path. In my book it is more of a cheater's ground. The reason why I say that is because once the receptacle is unscrewed from the box it no longer has a path to ground..

Huma - what many DIYers are not aware of and what confuses many or misleads them is the term "self grounding". The only safe way to install/utilize this type of receptacle (if not using a ground screw on the receptacle) is that it may only be installed in a metal box and the metal box must be grounded or this serves zero purpose in grounding the receptacle.

Many people think that have older homes with 2 prong receptacles and metal or plastic replacement boxes that are not connected to a ground back to the panel think that this receptacle will ground properly when in fact it will not at all. So the term "self grounding" is misleading in that respect,

The "clip" you are referring to is probably the grounding clip that is sometimes used instead of a screw to secure the ground wire to the metal box. That is a grounding option for the box. But again if the line to the box is not grounded or if the box itself is not grounded then this receptacle will serve no purpose in grounding.

I'm with Snoonyb - I am not a fan of this types and don't use them myself. I prefer the actual hard connection to the grounding screw of the receptacle.


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huma

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Huma

Look at the receptacle (outlet) below. The bottom part of the strap (ears) has that extra piece of metal on it which makes a more secure connection to the rest of the metal on the receptacle to complete the grounding path. In my book it is more of a cheater's ground. The reason why I say that is because once the receptacle is unscrewed from the box it no longer has a path to ground..

Huma - what many DIYers are not aware of and what confuses many or misleads them is the term "self grounding". The only safe way to install/utilize this type of receptacle (if not using a ground screw on the receptacle) is that it may only be installed in a metal box and the metal box must be grounded or this serves zero purpose in grounding the receptacle.

Many people think that have older homes with 2 prong receptacles and metal or plastic replacement boxes that are not connected to a ground back to the panel think that this receptacle will ground properly when in fact it will not at all. So the term "self grounding" is misleading in that respect,

The "clip" you are referring to is probably the grounding clip that is sometimes used instead of a screw to secure the ground wire to the metal box. That is a grounding option for the box. But again if the line to the box is not grounded or if the box itself is not grounded then this receptacle will serve no purpose in grounding.

I'm with Snoonyb - I am not a fan of this types and don't use them myself. I prefer the actual hard connection to the grounding screw of the receptacle.


View attachment 26181
The boxes are grounded (BX cable) but, it's over 20 receptacles that were installed some day in the past before I purchased this house and they are all grounded like that, Lutron TR receptacles without the self-grounding clip and no ground pigtail but show that they are grounded when tested with a receptacle tester because the screws provide metal to metal connection from the receptacle to the box. My concern is whether this kind of hack ground is safe or I should redo all the receptacles?
 

bud16415

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The boxes are grounded (BX cable) but, it's over 20 receptacles that were installed some day in the past before I purchased this house and they are all grounded like that, Lutron TR receptacles without the self-grounding clip and no ground pigtail but show that they are grounded when tested with a receptacle tester because the screws provide metal to metal connection from the receptacle to the box. My concern is whether this kind of hack ground is safe or I should redo all the receptacles?
My opinion is they are completely safe. With BX or metal conduit that is full run and properly grounded.



If you want to run a green ground wire from the grounding screw to a screw in the back of the metal box that would be a fine way to do it IMO.



I am not a pro electrician by the way just my opinion.

Before I retired I designed industrial equipment and in that everything runs in metal conduit and the machines frame is metal and it all becomes a big grounded thing. when I was taught back in the 70s something like a limit switch out remotely on the machine someplace we would run 2 wires to and the box ground was the conduit. Shortly before I retired I had a machine planed to be wired and the young electrician asked where are the green ground wires going to the limit switches. I asked him where will he connect them to a limit switch and he said to the box, and that’s how he was taught. I said go for it.
 

afjes_2016

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Huma
Yes, you are correct in saying you have metal-to-metal ground path in your case. To code? No. As safe as a ground pigtail from the box to the receptacle? No. How much more unsafe? I am not one to judge except that it is not to code.

If you are sure that you do in fact know that your metal boxes are grounded the I would say using a pigtail to a grounding box clip would be your best option here. The cost is minimal; safety improved though.

I am about to write far more than I need to in order to just say "yes, ground the receptacle with a pigtail" only because it is Sunday and I have the time to write a novel while I sip on a beer. :eek: Forgive an old man that has a lot of time on his hand and no one to talk to today. ;)

I say grounding clips because using screws (however less expensive) you may find it much harder to secure the grounding pigtail to the metal box.

If it was just one receptacle you had to deal with either method would be just as easy maybe; but since you are dealing with 20+ I would use a grounding clip (incase).

Several reasons why a grounding clip will be easier or better-
#1 - Attempting to hold the ground screw in your fingers and place it in the back of the box and hold it there while you are able to grab a few threads of the hole with your screw driver will be difficult especially if you have large fingers/hand. I guarantee it will aggravate you. You will not be able to get the screw far enough into the box to meet the screw hole without it dropping into the bottom of the box because you fingers can't get in far enough. Even with magnetic screwdriver it will be difficult. (See below for this method "trick screwdriver" if you choose this method).

#2 - Depending on how the box was hack/mounted etc and what it was mounted to, the hole that is threaded for the ground screw may be compromised/stripped with a sheet rock screw or some other type of screw. So the hole threads could be shot. Also, may not be enough room behind the screw for you to tighten it down far enough to be secured.

What method do I use usually? Simple - in my bag of tricks I have grounding screws and grounding clips. My first choice is a grounding screw. If I find the threading is stripped in the hole I go to a grounding clamp/clip.

"Trick Screwdriver"
I learned very early in my trade to have one of these in my bag of tricks for grounding screws.
It's a bit difficult to see but the tip of the screwdriver is designed to expand and hold the screw steady and outward when the handle is slid forward. If you have never seen one and don't know quite what I am talking about it is almost like "You had to be there" kind of thing. The link I gave you is not the specific one/size you may need but just a representation for visual illustration.

Klein Tools 1/4 in. Slotted Screw-Holding Flat Head Screwdriver with 4 in. Round Shank-K34 - The Home Depot

1626624808149.png



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Jeff Handy

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When you form a loop in your green ground wire pigtail, make it tight.
The that tight loop will hold and control the grounding screw as you feed the wire to the back of the box.
 

Eddie_T

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Although I am careful to maintain the grounding system I have yet to experience an appliance failure that it is designed to protect me from. The same with GFCI though I have experienced a failure of a GFCI device itself.
 

bud16415

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I believe BX is the old term that has hung on to describe all armored cable and there is newer armored cable called AS that everyone still calls BX. AS has a copper or aluminum ground bonded to the inside of the steel coiled armor.



As far as I know the AS version of BX cable is still to code using the armor sheath as the ground. I could be wrong.



I do it like @Jeff Handy and make a ring on the end of the wire and put it around the screw and use the wire to hold the screw. Clips are fine too.

There is a lot that can go wrong when using the armor as a ground in any case as all the clamps along the way have to be making good contact.
 

Jeff Handy

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I believe BX is just the empty metal spiral flex conduit, in steel.
MC cable is aluminum spiral flex conduit with wires inside.
I have not heard of or used any cable called AS ,but I have not done that kind of wiring for several years.
I always bought the MC cable with the green grounding wire inside.
Even though the flex conduit is grounded, people tend to abuse it and it can pull out of the connector fittings sometimes.
Such as idiots hanging laundry from it in the basement, or heavy items hung from it in a garage.
It does not meet code in my area near Chicago, but it is widely used and inspectors seem to ignore it, as long as it is done well and properly supported.
 

bud16415

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I believe BX is just the empty metal spiral flex conduit, in steel.
MC cable is aluminum spiral flex conduit with wires inside.
I have not heard of or used any cable called AS ,but I have not done that kind of wiring for several years.
I always bought the MC cable with the green grounding wire inside.
Even though the flex conduit is grounded, people tend to abuse it and it can pull out of the connector fittings sometimes.
Such as idiots hanging laundry from it in the basement, or heavy items hung from it in a garage.
It does not meet code in my area near Chicago, but it is widely used and inspectors seem to ignore it, as long as it is done well and properly supported.
I typed AS it is AC (old age).



Here is the whole story from some pros.



bx cable for equipment ground
 

Eddie_T

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I haven't purchased a receptacle in years and just learned today that Eaton receptacles have built-in wire strippers. My arrows may point to the wrong end. I did know about the stripping gauge.

Screenshot 2021-07-21 1.59.18 PM.png
 
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huma

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Thanks for all the great tips!
@afjes_2016 @bud16415
Although I'm still not sure what would be the correct way to use a grounding clip instead of a screw. Where would be the right spot to attach it and how does it secure the pigtail..
 

bud16415

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Thanks for all the great tips!
@afjes_2016 @bud16415
Although I'm still not sure what would be the correct way to use a grounding clip instead of a screw. Where would be the right spot to attach it and how does it secure the pigtail..
 

afjes_2016

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The clips are designed to place the ground wire in the clip and then slip the clip onto the edge of a metal box. I prefer a grounding screw to the back of the box but then sometimes you don't have the option and have to go with a clip.

Of course for this method to be effective the box itself must be grounded.

There are many videos on youtube on how to install them.



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