Basic Grounding Wire Question in Receptacle Box - Please Help.

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Hi. I'm replacing an old switch for a ceiling fan that only had 2 wires; a black and a white. The new switch has 3 wires, a black, white and a green grounding wire. The wire coming into the receptacle box area through the wall has 3 wires, a black, a white and a bare copper wire and the bare copper wire is just connected to a screw on the metal receptacle box. My question is when I install the new switch that now has a green grounding wire, what do I do with it or how do I connect the new green grounding wire to the receptacle box. Can I just wrap it around the screw that the bare copper grounding wire is wrapped around and have 2 wires connected to that one screw? If not, where does that green grounding wire on the new switch go and how do I do it? Right now everything is connected and the ceiling fan & light works fine except that I don't have that green grounding wire on the new switch attached to anything (just wrapped it in electrical tape for the time being) and I want to make sure it's safe. Many thanks to all. Very much appreciated.
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There is probably another 10/32 tapped hole that you can put a screw in and wrap it around, or you can just cut it off as the screws attaching the switch to the grounded metal box are sufficient for grounding purposes.
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OR, he could do it properly and pigtail the bare ground conductors and the green wire from the new switch using a greenie wirenut which would allow one of the bare conductors to be left long and be bonded to the box via the 10/32 grounding screw that is already there...
~~ Evan
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On 06/03/2010 10:43 PM, Evan wrote:

No, you can't have two wires under one screw. I suppose you could solder on spade lugs or ring terminals but that is not common practice and I do not know if that is acceptable by code. The only exception to the "one wire per screw" rule is with compression-type terminals on some better devices, where you don't loop the wire but push it straight in a little hole and then tighten the screw which has a square clamping washer under the head - but I have never seen one of those on a ground connection, only the hot and neutral. (doesn't mean that it doesn't exist, and it would be awful handy for situations just like this, but I've never seen it.)

Not true unless the switch is labeled "self grounding" or similar. Most "spec grade" switches are so labeled, most consumer grade ones are not. In actuality, it is probably grounded, but by code, it is not considered to be so unless it is specifically rated for self grounding.

yes, exactly. Or if you don't have any greenies but do have a few electrical spare parts, just unhook the incoming ground wire from the screw, then splice it to two short lengths of appropriate gauge (probably 14AWG, possibly 12AWG) bare or green insulated wire with a wire nut. One wire goes back under the screw to the box; one goes to the screw on the yoke of the switch. If the ground wires are bare and space in the box is tight, consider wrapping the switch with a turn or two of electrical tape to remove the possibility of a ground wire hitting one of the screw terminals as you shove everything back in the box.
If I were wiring this new, I would probably leave the ground wire long, loop it under the screw in the box, then under the screw on the yoke to save a wire nut and some space in the box (I'm assuming that since there was only a mention of one cable that this is a switch leg and that it doesn't have to be spliced to another ground wire in another cable.)
nate
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Sorry Nate, you're thinking receptacles, not switches. Look up NEC 404.9

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On 06/03/2010 11:14 PM, RBM wrote:

You may be right, I dunno. My copy is at work. I don't really worry about it, I figure the connection is there, I might as well use it. Besides, I have a thing for antique brass switch plates (you know, the .040" or thicker ones with the nice crisp bevels) so good grounding is a Good Thing. I've been using the connections as I go and trying to do everything right; I've even been going ahead and grounding the supposedly self-grounding receptacles. Hopefully the next owner of this place - if there is one (land is worth way more than the house; entirely possible that someone might buy it, knock it down, and build a McMansion) will appreciate it. Or they might just rip out all the stuff I did and put in Decora out of a contractor pack :/
At least I don't stay up at night worrying about any work that I've done. Now the guy that was in there before me... (shudder)
nate
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OR, he could do it properly and pigtail the bare ground conductors and the green wire from the new switch using a greenie wirenut which would allow one of the bare conductors to be left long and be bonded to the box via the 10/32 grounding screw that is already there...
~~ Evan
The OP said he has one grounding conductor, and it's already around the grounding screw in the box. I'm assuming that if there was additional slack on that conductor, the OP would have already figured out that he could splice it to the grounding conductor of the switch. NEC 404.9 allows for metal screws on a snap switch attaching to a metal box, to serve as a proper grounding method
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.
Evan - So if I understand correctly, remove the bare copper wire coming from inside the wall from under the screw and connect/twist that with both the green wire from the switch and add another separate wire lead that then connects to the screw? So, the 3 ground wires would be connected via the wirenut and just the one new wire I added goes to the screw? Can you just confirm I got that right. So it's dangerous to wrap 2 green ground wires around that one screw? Thanks for the clarification very much appreciate and education.
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...
It isn't necesarily dangerous to put two wires under one screw, if you are careful you can get a good connection for both wires, but there is a much greater chance of one of the wires slipping out from under the screw and touching anything else in the box, some of which could be hot. So, Evan and Nate have good suggestions.
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On Thu, 3 Jun 2010 20:17:03 -0700 (PDT), "hr(bob) snipped-for-privacy@att.net"

It's common practice on bare copper grounds to just twist them together, and then trap one or both under the screw - but that doesn't work with the stranded and insulated ground.
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On 06/04/2010 09:15 PM, snipped-for-privacy@snyder.on.ca wrote:

I remember back in the day taking receptacles out and just finding the grounds spliced as normal but with no wire nut at all, just wires twisted together. I always thought that was a little cheezy, was that acceptable by code at one point in time, or was I just looking at shoddy work?
nate
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Nate Nagel wrote:

In the US it is not acceptable to put 2 wires under a screw. It is also not acceptable to twist ground wires and not use a wire nut. Far as I know neither has ever been code compliant.

Shoddy work.
--
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wrote:

AFAIK it is still acceptable on bare copper ground wires.
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snipped-for-privacy@snyder.on.ca wrote:

I don't believe canada was ever that backward.
--
bud--

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Evan - So if I understand correctly, remove the bare copper wire coming from inside the wall from under the screw and connect/twist that with both the green wire from the switch and add another separate wire lead that then connects to the screw? So, the 3 ground wires would be connected via the wirenut and just the one new wire I added goes to the screw? Can you just confirm I got that right. So it's dangerous to wrap 2 green ground wires around that one screw? Thanks for the clarification very much appreciate and education.
Yes, you can splice the two wires together, with a pigtail, and wrap that under the screw. The "greenie" he mentions, is a wire nut with a wire already connected to it.
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...
RBM - Oh, I see. (1) get a "greenie" and then (2) twist the bare ground wire and the switch wire under the "greenie", then the wire coming out of the top of the greenie goes to the screw? Do I have it right now? Thanks to all. This is a great group!!
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RBM - Oh, I see. (1) get a "greenie" and then (2) twist the bare ground wire and the switch wire under the "greenie", then the wire coming out of the top of the greenie goes to the screw? Do I have it right now? Thanks to all. This is a great group!!
That'll work just fine.
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om...
As an FYI to all, I was just privately email another suggestion which was to use one of these; a "grounding pigtail". - See link attached. What are your thoughts about this. I guess it does the exact same thing as the greenie. (Amazon.com product link shortened)
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On 06/03/2010 11:36 PM, Pinboozie wrote:

Sort of. The pigtail you can make yourself if you have a box of ground screws and some wire. Here's a "greenie"
http://www.idealindustries.com/products/wire_termination/twist-on/wing-nut_greenie.jsp
combines the pigtail and wire nut into one part. Accomplishes the same thing, though.
nate
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om...
Nate - Great! Thanks for that link. The greenies I saw didn't have the top wire built in like that one. This would be perfect as I would just have to connect the copper wire coming in from the wall with the switch ground wire under the greenie and attach the top wire of the greenie to the screw. Perfect....I'll try to track one down tomorrow and go that route....Thanks Again. I'll let you all know how I made out.
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