3 cable juntion box (metal) - 3 or 4 grounds wires?

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Old 03-30-18, 12:01 AM
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3 cable juntion box (metal) - 3 or 4 grounds wires?

Hi.

I've got a metal junction box that I used to send a branch off of another 14/2 cable. I used a metal junction box and forgot to connect the ground wire to the box, so I'm going to go back and correct it.

I tied all 3 cables grounds together. Do I make a pigtail and put a total of 4 wires under the wire nut or is it better to simply secure one of the 3 wires to the back with a green screw?
 
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Old 03-30-18, 12:15 AM
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Do I make a pigtail and put a total of 4 wires under the wire nut or is it better to simply secure one of the 3 wires to the back with a green screw?
It must be all four. You only have one ground in and it must be connected to all grounds out therefore all grounds must be connected together.

You could use a green grounding wire nut which has a hole in the top so one ground wire can extend on to the box.
 
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Old 03-30-18, 02:28 AM
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Originally Posted by ray2047 View Post
It must be all four. You only have one ground in and it must be connected to all grounds out therefore all grounds must be connected together.

You could use a green grounding wire nut which has a hole in the top so one ground wire can extend on to the box.
I don't understand "one ground in". I have 3 cables coming into the box all tied together with all 3 ground wires tied together. Why can't I just loop part of a ground wire under a screw on the metal box? I've seen it done. I mean as long as all the ground wires are touching each other and the metal box wouldn't that work?

PS: The picture is old and everything wrong in it, including black tap, length of cables being too short inside box, and backwards cable clamps has been corrected.
 
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Old 03-30-18, 03:09 AM
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Why can't I just loop part of a ground wire under a screw on the metal box?

You can if it is connected to all the other ground wires.

I don't understand "one ground in".

Only one bare wire is really ground back to the panel. The other bare wires are not grounds unless connected to the bare wire that goes back to the ground at the panel. Only the power in cable has a wire to panel ground.

I believe we had a misunderstanding when you wrote:
is it better to simply secure one of the 3 wires to the back with a green screw?
You made no mention of connecting the wire to the ground screw to the other wires.
 

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Old 03-30-18, 12:20 PM
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Originally Posted by ray2047 View Post
You can if it is connected to all the other ground wires.




Only one bare wire is really ground back to the panel. The other bare wires are not grounds unless connected to the bare wire that goes back to the ground at the panel. Only the power in cable has a wire to panel ground.

I believe we had a misunderstanding when you wrote: You made no mention of connecting the wire to the ground screw to the other wires.
Thanks Ray. Sorry for the confusion and thanks for all your advice! Yes, the wire that would go under ground screw would be one of the wires that are all connected together under the wire nut for the grounds.
 
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Old 04-02-18, 08:14 AM
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"Yes you can loop any one of the ground wires around the green screw in the back of the box first provided that the wire is long enough to come back out and be wire nutted to the other two ground wires."

If you have the green wire nut with the hole in the small end but none of the ground wires are long enough to go through as pictured then you will need a pigtail as a fourth wire to connect to the screw in the box.

It is easier for a "single ended" pigtail to come out the large end of the wire nut with the other wires as opposed to go out the small end but if applicable a single longer pigtail for ground wires can have its middle in the wire nut instead of having two separate pigtails.
 
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