Ground wires in light switch box

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  #1  
Old 07-15-14, 01:09 PM
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Ground wires in light switch box

I'm replacing a few switches in my house, and I've found there are four ground wires coming into (or possibly going out of) the box via 4 separate cables. None of the grounds were connected to the two switches in the box, but they were all pigtailed together.

Here's an explanation of the four cables :

1. 3 wire cable: White, red, and black connected to their terminals on a three-way switch (switch A), ground pigtailed.
2. 2 wire cable: black pigtailed with two other black wires (see below) white pigtailed with two other white wires (see below), ground pigtailed.
3. 2 wire cable: black to single pole switch (switch B) white pigtailed to two others
4. 2 wire cable: both the white and black wires pigtailed to their respective clumps that I mentioned above. This cable comes from the bottom of the box, while the other two come from the top, if that's any aid.

I've attached a very rough diagram as well. Black is black, gray is white, red is red, green is ground. The three circles are pigtails, the two boxes on the left and right are the switches. Thanks!Name:  Photo on 7-15-14 at 3.04 PM.jpg
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  #2  
Old 07-15-14, 01:51 PM
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pigtail off the bundle to each switch using a crimp to keep the bundle together (may be required in some locations).
 
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Old 07-15-14, 01:51 PM
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If the box is non metallic the grounds must be pigtailed to the switch. If the box is metal the grounds must be pigtailed to the box and pigtailed to the switch.
 

Last edited by ray2047; 07-15-14 at 07:35 PM. Reason: Possible Error
  #4  
Old 07-15-14, 07:04 PM
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If the box is metal the grounds must be pigtailed to the box. Optional for metal boxes but best practice also pigtailed to the switch.
Wouldn't the switches have to be self grounding OR the metal box be a 1900 box with raised cover if no pigtail is installed to the switch?
 
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Old 07-15-14, 07:33 PM
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I was corrected on the forum once because I said to run a pigtail to a switch in a metal box. There wasn't a code cite but it was not in reference to a self grounding switch or specific box. Info may have been wrong. I will edit my post.
 
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Old 07-19-14, 05:09 AM
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Metal boxes are required to be grounded.

Switches do not need to be self grounding. Switches mounted to a metal box with metal screws are considered grounded per NEC 404.9(B)(1)
 
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Old 07-19-14, 06:14 PM
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Switches do not need to be self grounding. Switches mounted to a metal box with metal screws are considered grounded per NEC 404.9(B)(1)
I don't believe I have read that specific reference before, but I can clearly see you are right. That being said, I don't agree with the reference. My opinion is that if a receptacle needs a grounding pigtail (or to be self grounding) to be properly grounded a switch should have the same requirement. Like I said, that is just my opinion for what it's worth.
 
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Old 07-19-14, 06:22 PM
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I have also wondered why it is not required for switches to be self grounding similar to receptacles.
 
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Old 10-31-14, 09:10 AM
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I always personally ground every switch and electrical outlet to a ground wire even if the box is metal but I am wondering am I doing it overkill/wasting time/space in the box? I've read the code allows you to ground the switch to a metal box via the switch screws but are you also allowed to do that with a power outlet or GFCI outlet? Is it wiser to just ground everything with a ground wire even if a ground can be established through the screw?
 
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Old 10-31-14, 01:42 PM
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Code also allows for the use of a complete metallic conduit system in place of an independent equipment grounding conductor but I always add a grounding conductor to conduit jobs. I do not think it is overkill to add equipment grounding conductors to switches or receptacles even if they are grounded via their mounting.
 
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