Grounding clips advice

Reply

  #1  
Old 01-15-15, 09:26 PM
Member
Thread Starter
Join Date: Oct 2005
Location: Florida
Posts: 1,445
Grounding clips advice

I have a bunch of old 1960s existing boxes where the devices weren't grounded.

Everything is EMT with metal boxes. So all I need to do is to bond a ground wire from the device to the box.

Interior walls are no issue, I can drill a hole through the metal box for a ground screw.

Exterior walls is where I run into problems. The boxes are shot into concrete walls, and these old boxes do not have a raised section on the back side to accommodate the ground screw.

I understand that in this case a ground clip can be used. However this is an existing box with an existing mud ring, so I can't attach the clip to the edges of the metal box, I need to attach it to the inside edge of the mud ring? Is that how it is supposed to be used?

But the mud ring is raised in the middle, so the clip won't actually fully sit all the way in. In any case I think grounding clips won't work either.



Any advice on how to do this?

I know one solution is to scrap off the section of the mud ring that's painted, then use self grounding switches and receptacles. For another reason I don't want to use self grounding devices.

Is drilling a hole in the mud ring and tying a ground wire to that one option?
 
Sponsored Links
  #2  
Old 01-15-15, 10:15 PM
PJmax's Avatar
Group Moderator
Join Date: Oct 2012
Location: NJ - USA
Posts: 43,504
Is drilling a hole in the mud ring and tying a ground wire to that one option?
I believe code requires a green self threading screw so if you drill and tap for a green ground screw you should be ok. Nor really much other choice other than pulling a ground wire thru the conduit.
 
  #3  
Old 01-15-15, 11:02 PM
Member
Thread Starter
Join Date: Oct 2005
Location: Florida
Posts: 1,445
if I just drill the metal box with a regular bit the bit would make it half way through the metal and be stopped by the concrete behind it. If I then use a concrete bit it will probably chew through the hole and ruin the threads.
 
  #4  
Old 01-15-15, 11:35 PM
PJmax's Avatar
Group Moderator
Join Date: Oct 2012
Location: NJ - USA
Posts: 43,504
Drill and tap the hole in the cover plate.
 
  #5  
Old 01-16-15, 04:49 AM
pcboss's Avatar
Forum Topic Moderator
Join Date: Jul 2002
Location: Maryland
Posts: 14,363
Plaster rings typically have a curved surface that would not allow the clip to fit properly.

Self grounding would be much less hassle.
 
  #6  
Old 01-16-15, 06:01 AM
Member
Thread Starter
Join Date: Oct 2005
Location: Florida
Posts: 1,445
I am not getting it. Drill and tap the cover plate?
 
  #7  
Old 01-16-15, 06:04 AM
Member
Thread Starter
Join Date: Oct 2005
Location: Florida
Posts: 1,445
I can't use self grounding devices because it will only solve some of the issues. Some of these I have dimmers or fan speed controls or dual sliders specific for a brand of fixtures and don't have self grounding versions of them.
 
  #8  
Old 01-16-15, 06:17 AM
Forum Topic Moderator
Join Date: Feb 2005
Location: Near Lansing, Michigan
Posts: 10,296
I would probably run a small bit in the hammer drill through one of the factory holes in the back of the box to remove some material, then just drive in the ground screw, impact drive if necessary. You could also shorten the ground screws a little bit with side cutters if it's too difficult to drive all the way. If that fails spectacularly then back to the drawing board, but it's worth a shot.
 
  #9  
Old 01-16-15, 06:58 AM
Handyone's Avatar
Forum Topic Moderator
Join Date: Aug 2000
Location: U.S.
Posts: 5,451
I don't think you will ruin the hole by drilling twice. The ground screws are self-tapping.
So just drill a hole in back of box with regular bit, a little smaller than ground screw.
Go through that hole with a diamond bit, a little smaller. All you need to do is clear out about 3/8" of concrete.

Use a drill/driver to drive in ground screw using a magnetic hex head bit. The screw will cut it's own threads.
 
  #10  
Old 01-16-15, 07:02 PM
Member
Thread Starter
Join Date: Oct 2005
Location: Florida
Posts: 1,445
I did the concrete drilling and taped a hole, no good, when driving the ground screw it just spins and spins. I think it can't get past the smaller hole in the concrete.

After some thinking there are only two options that come to mind, both not very attractive and laborious.

(1) Drill a ground screw size hole in the metal, then drill a smaller size hole beyond the first hole in the concrete; then use a smaller concrete bit and drill at an angle through the metal hole into the concrete, hoping to break up more of the concrete without enlarging the metal hole. Do this all the way around, drilling half a dozen spots. Then secure the ground screw to the tapped hole.

or

(2) cut into the edge of the metal box, break up the sheet rock around the mud ring, and expose the entire mud ring. Back out the two screws and remove the mud ring, then use a grounding clip on the side of the box. Put back the mud ring then reapply new joint compound to refinish the wall.

Not really what I want to do, but seems this should be a common problem and there is really no clean solution?
 
  #11  
Old 01-16-15, 08:04 PM
Handyone's Avatar
Forum Topic Moderator
Join Date: Aug 2000
Location: U.S.
Posts: 5,451
Try drilling the hole in the metal a little larger. The self tapping screw should grab.
The metal's soft.
If you already tried that, I'm guessing the concrete is really hard? It doesn't crumble?
 
  #12  
Old 01-16-15, 08:05 PM
Justin Smith's Avatar
Member
Join Date: Dec 2010
Location: Cressona, Pa, USA
Posts: 2,546
Depending on the brand ground screws you use, you may need to tap a hole. The ones at my supply house need to be tapped 10-32.

If I was you I'd use self-grounding devices.
 
  #13  
Old 01-17-15, 05:52 AM
Member
Thread Starter
Join Date: Oct 2005
Location: Florida
Posts: 1,445
Justin I tapped a hole, problem is the concrete behind the hole. The ground screw won't "drive" in even if I drill with a smaller concrete but into that hole, I need to somehow make the hole in the concrete bigger without making the tapped metal hole bigger.

Right now the ground screw just spins in place.

Is there such a thing as a GROUNDING TAPCON SCREW?
 
  #14  
Old 01-17-15, 06:09 AM
Member
Thread Starter
Join Date: Oct 2005
Location: Florida
Posts: 1,445
OK here is thinking out loud.

What if I use a conduit clamp?



I drill a 3/16" through the metal, into the concrete, then bond the clamp to the box and the concrete with a Tapcon screw. Now the clamp is bonded to the box, metal to metal.

I then drill and tap a hole for a ground screw on the curved part of the clamp that raises from the box, and put in a ground screw.

Practically I think this should work, is it against code?
 
  #15  
Old 01-17-15, 07:09 AM
ray2047's Avatar
Group Moderator
Join Date: Mar 2006
Location: USA
Posts: 32,671
The pros will have to weigh in on this but why not "Tapcon" a grounding clip to the box. I'm thinking the conduit clamp might take up too much space.
 
  #16  
Old 01-17-15, 08:55 AM
Tolyn Ironhand's Avatar
Group Moderator
Join Date: Nov 2007
Location: Twin Cities, MN
Posts: 11,989
Switches connected to a grounded metal box are considered to be grounded. 404.9(B)(1)

Use self grounding receptacles.

Only issue you will have is with special devices like GFCI's that do not come in self grounding type.
 
  #17  
Old 01-17-15, 10:23 AM
Member
Thread Starter
Join Date: Oct 2005
Location: Florida
Posts: 1,445
Toyln,

"Switches connected to a grounded metal box are considered to be grounded. 404.9(B)(1)"

I wanted to make sure I understand this.

It is a metal box with EMT conduit back to the panel, and the panel is grounded to the outside.

So I could ground the switch simply by connecting the yoke of a switch to the metal mud ring on the metal box with metal screws?

I assume the cardboard retainer for the screw needs to be removed? Or is the grounding provided via the screw and not the metal contact between the yoke and mud ring?

If this is the case, can I not ground a receptacle in that same box, by connecting it's green screw via a jumper to the green screw of the switch, which is grounded by screwing to the metal box?
 
  #18  
Old 01-17-15, 10:44 AM
pcboss's Avatar
Forum Topic Moderator
Join Date: Jul 2002
Location: Maryland
Posts: 14,363
Remove the washer.

Don't you have two gang rings with tapped holes for both devices?
 
  #19  
Old 01-17-15, 01:01 PM
Tolyn Ironhand's Avatar
Group Moderator
Join Date: Nov 2007
Location: Twin Cities, MN
Posts: 11,989
can I not ground a receptacle in that same box
Yes, use a self grounding receptacle. While the screws do make a ground connection the same as the switch, it is not tested/listed for that use. A self grounding device is.

You do not need to remove the washer, it is the connection of the screw threads and the head of the screw on the yoke that makes the connection(s).
 
  #20  
Old 01-17-15, 07:04 PM
Member
Thread Starter
Join Date: Oct 2005
Location: Florida
Posts: 1,445
Yes, use a self grounding receptacle. While the screws do make a ground connection the same as the switch, it is not tested/listed for that use. A self grounding device is.
I understand that and probably will use self grounding receptacles, but I am curious, if the switches are grounded by simply screwing the yoke onto the metal box with metal screws, will a non-self grounding receptacle be properly grounded by connecting a green jumper to the green screw of that grounded switch?
 
  #21  
Old 01-17-15, 07:46 PM
Tolyn Ironhand's Avatar
Group Moderator
Join Date: Nov 2007
Location: Twin Cities, MN
Posts: 11,989
No. By attaching a switch to the metal box you are only grounding the switch yoke and a metal face place, if attached. It is not a good enough ground for grounding anything connected to a receptacle. If it was then just a standard receptacle would be good enough, because if you look at how a receptacle is constructed, the ground screw is part of the metal yoke of the device just like it is on a switch and there would be no need for a self grounding receptacle.
 
  #22  
Old 01-20-15, 06:48 AM
Forum Topic Moderator
Join Date: Feb 2005
Location: Near Lansing, Michigan
Posts: 10,296
I don't suppose you know anyone with a little 120V buzz box stick welder? :-) You could tack a screw lug (hex nut) onto the back of the box pretty easily with one quick pop.
 
  #23  
Old 02-10-15, 06:06 PM
Member
Join Date: May 2012
Posts: 2
receptacles with self-grounding clip

The picture looks like a 4x4 box with a metal mudring for a single receptacle which is screwed on to a 4x4 box. The 4x4 box is grounded. And you would think that the mudring would be adequately grounded as well. There is a bit of a debate going on about this on the Mike Holt forum under "Self Grounding Receptacles" referencing NEC "250.146(B) Contact Devices or Yokes. Contact devices or yokes designed and listed as self-grounding shall be permitted in conjunction with the supporting screws to establish the grounding circuit between the device yoke and flush-type boxes."

I have often been using the more expensive receptacles - which have a self-grounding clip, And I do NOT bother running a ground wire to the self-grounding receptacle.

But I read recently that this NOT OK because the metal mud-ring is 'screwed on' to the metal box. This does not make sense to me, but I suppose the logic is that the metal mud ring could get loose.
 

Last edited by ryeisenman; 02-10-15 at 06:26 PM.
  #24  
Old 02-11-15, 06:42 AM
CasualJoe's Avatar
Member
Join Date: Jan 2010
Location: USA
Posts: 9,221
But I read recently that this NOT OK because the metal mud-ring is 'screwed on' to the metal box. This does not make sense to me, but I suppose the logic is that the metal mud ring could get loose.
This is incorrect, the plaster ring is effectively grounded when scewed to the box. Using the logic that the plaster ring could come loose would eliminate being able to use the conduit as an effective ground path as well; the connectors could come loose. I want to add that when using a raised 1900 duplex receptacle cover, a ground wire to the device is not necessary if the box is grounded.
 
  #25  
Old 02-11-15, 01:39 PM
Member
Join Date: Oct 2005
Location: USA
Posts: 1,147
I"ve had to deal with this and its a pain for sure. The drill bits that will drill steel will quickly dull when they hit the concrete block, and a carbide masonry bit won't drill through steel. What I eventually did was to use the proper #21 tap drill bit, then use a masonry bit that will clear that hole, a 1/8" to deal with the concrete. work it around as much as the box will allow. Then, tap the hole with 10-32. Hopefully, these are CMU's. If poured concrete (harder to get that clearance hole made), I'd go self-grounding device.
 
  #26  
Old 03-14-15, 06:17 AM
Member
Thread Starter
Join Date: Oct 2005
Location: Florida
Posts: 1,445
OK this is an older thread, and what I ended up doing, which was insanely laborious was using a combination of methods. In some cases where it's a single 1 gang receptacle I used a self grounding receptacle, in other cases where it's not concrete behind the method box like interior walls, I used tapped a new hole in the back of the box and thread in a ground screw, in a few cases I have two gang boxes with multiple switches and concrete behind the box I end up enlarging the sheet rock hole enough with a multitool to expose the old mud ring fully, removed the mud ring so I can insert a grounding clip and put the mud ring back in, in one case there was only one conduit feeding the box I end up removing the box from the concrete block wall, and put in a new metal box with a raised ground screw hole.

However, a few days ago I was browsing through Garvin Industries web site and I saw a product that I could have used I didn't even know existed...a locknut with an integrated grounding hole!



I just wanted to share because if I knew about it it could have saved me a bunch of time.
 
  #27  
Old 03-14-15, 06:54 AM
ray2047's Avatar
Group Moderator
Join Date: Mar 2006
Location: USA
Posts: 32,671
Thank you for sharing your solutions. It will be helpful to others.
 
  #28  
Old 03-14-15, 02:02 PM
Tolyn Ironhand's Avatar
Group Moderator
Join Date: Nov 2007
Location: Twin Cities, MN
Posts: 11,989
The only issue I see with that locknut is there is no way you could spin it 360 degrees. The screw bump would hit the side of the box and you couldn't tighten it.
 
  #29  
Old 03-14-15, 03:34 PM
Handyone's Avatar
Forum Topic Moderator
Join Date: Aug 2000
Location: U.S.
Posts: 5,451
That's a nifty device and I've never seen or heard of them.

I think what you did was better though. I would like to see the ground wire securely attached directly to box. A ground screw is the ideal way, a clip will do the job. This ring has room for failure.
 
  #30  
Old 03-14-15, 07:36 PM
CasualJoe's Avatar
Member
Join Date: Jan 2010
Location: USA
Posts: 9,221
The only issue I see with that locknut is there is no way you could spin it 360 degrees. The screw bump would hit the side of the box and you couldn't tighten it.
That is probably why the major manufacturers haven't developed their own version of this product.
 
  #31  
Old 03-17-15, 03:24 PM
Member
Thread Starter
Join Date: Oct 2005
Location: Florida
Posts: 1,445
The only issue I see with that locknut is there is no way you could spin it 360 degrees. The screw bump would hit the side of the box and you couldn't tighten it.
Possibly, I guess that depends on the depth of the metal box, and whether you have other connectors immediately adjacent that would interfere with the nut rotating 360. I had at times not even able to rotate a 3/4" lock nut if the adjacent connectors are 3/4". May be with 1/2" connectors this works.

Another potential issue is the screw kind of have to face out for someone to tighten it down with a regular screwdriver, so if you turn and turn to tighten it down and it ends up on the other side of the box opening you have to swing it back around. I could see much of it depends on how much room you have to work with. If you have an existing two gang metal box with a single device mud ring under the finished wall, it's going to be difficult to use a screw driver to secure a ground screw unless it's for the top or bottom middle connectors.

I think it would be more useful, if this grounding lock nut is made as a "ring" or washer. You turn the ring to face wherever you want and put it onto the male threaded connector, then you put a regular lock nut over it to tighten, so it goes between the lock nut and the inside of the box.
 
Reply

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Thread Tools
Search this Thread
Display Modes
'