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Old 09-11-2012, 06:03 PM   #1
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does every metal box need to be grounded?


I was wondering if every metal receptacle need to be grounded via a green ground screw screwed in a hole in the back and connected to the other ground wires coming into and out of the box, in addition to the ground terminal of the possible power outlet or light for which the box is used. Also, if the box is used only as a JB, does it still need to be grounded?

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Old 09-11-2012, 06:06 PM   #2
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does every metal box need to be grounded?


I don't believe it is a requirement that the screw be green.

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Old 09-11-2012, 06:13 PM   #3
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does every metal box need to be grounded?


Yes and yes, it shall be a green screw
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Old 09-11-2012, 06:14 PM   #4
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does every metal box need to be grounded?


Green screw citation?
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Old 09-11-2012, 06:41 PM   #5
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does every metal box need to be grounded?


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Yes and yes, it shall be a green screw
It doesn't have to be green...
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Old 09-11-2012, 06:42 PM   #6
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does every metal box need to be grounded?


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Originally Posted by amakarevic View Post
I was wondering if every metal receptacle need to be grounded via a green ground screw screwed in a hole in the back and connected to the other ground wires coming into and out of the box, in addition to the ground terminal of the possible power outlet or light for which the box is used. Also, if the box is used only as a JB, does it still need to be grounded?

Thanks
Every metal box needs to be bonded to the grounding conductor...
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Old 09-11-2012, 06:50 PM   #7
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does every metal box need to be grounded?


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Every metal box needs to be bonded to the grounding conductor...
Yet, I believe it is possible for the box to BE the grounding conductor (e.g. Conduit?)
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Old 09-11-2012, 06:54 PM   #8
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does every metal box need to be grounded?


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Yet, I believe it is possible for the box to BE the grounding conductor (e.g. Conduit?)
The conduit would be the EGC.... and the box would be bonded by that wiring method.
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Old 09-11-2012, 07:11 PM   #9
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does every metal box need to be grounded?


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The conduit would be the EGC.... and the box would be bonded by that wiring method.
But couldn't the box act as (a part of) the EGC in the middle of a conduit run? Otherwise, what bonds one pipe to the other?

Last edited by jlmran; 09-11-2012 at 07:16 PM.
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Old 09-11-2012, 07:22 PM   #10
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does every metal box need to be grounded?


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It doesn't have to be green...
But how will the electrons know that it is a ground screw and not a regular screw.
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Old 09-11-2012, 07:24 PM   #11
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does every metal box need to be grounded?


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But how will the electrons know that it is a ground screw and not a regular screw.
well if there is one electron missing, you can be positive its a ground screw
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Old 09-11-2012, 07:31 PM   #12
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does every metal box need to be grounded?


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I was wondering if every metal receptacle need to be grounded via a green ground screw screwed in a hole in the back and connected to the other ground wires coming into and out of the box, in addition to the ground terminal of the possible power outlet or light for which the box is used. Also, if the box is used only as a JB, does it still need to be grounded?

Thanks
Your title asks one question and your post asks another.

Does every metal box need to be grounded.....I would say yes. We could argue about special circumstances, but the rule is yes.

Your post asks if every metal receptacle needs to be grounded...I would say yes. A receptacle is not a box. Do you have to use the the green ground screw in the back of a metal box to ground a receptacle? Not necessarily. Some receptacles are self grounding. You could use a self grounding receptacle and attach it to a grounded box and would be fine.

Does a metal box containing wires that is just used as a junction box need to be grounded...Yes. I would use the equipment grounding conductor you pulled with the circuit and bond that to the back of the box via the pre-drilled and tapped hole that is provided.

Now, if you use metal conduit and properly connect your fittings to your metal boxes, then you would not have to use a green ground wire with your circuit. Your conduit would be your equipment ground and would take the place of the green ground wire. But you still would have to connect any grounding means from a light fixture, receptacle, etc to the back of the metal box via the pre-drilled and tapped hole that is provided.

Lets make this real simple. ALL METAL boxes, conduit, etc used in an electrical system needs to be grounded. How you ground them is where it gets interesting.
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Old 09-11-2012, 07:31 PM   #13
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does every metal box need to be grounded?


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It doesn't have to be green...
It says in 250.126 that the terminal for the connection of the equipment grounding conductor shall be identified by one of the following:
1) A green, not readily removable terminal screw with a hexagonal head.
2) green, hexagonal, not readily removable terminal nut.
3) A green pressure wire connector. If the terminal for the grounding conductor is not visible, the conductor entrance hole shall be marked with the word Green or ground, the letters G or GR, a grounding symbol, or otherwise identified by a distinctive green color. If the terminal for the equipment grounding conductor is readily removable, the area adjacent to the terminal shall be similarly marked.
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Old 09-11-2012, 07:41 PM   #14
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does every metal box need to be grounded?


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well if there is one electron missing, you can be positive its a ground screw

I'll add to the jocularity....if it's a ground screw it can't be positive
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Old 09-11-2012, 07:48 PM   #15
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does every metal box need to be grounded?


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Your title asks one question and your post asks another.

Do you have to use the the green ground screw in the back of a metal box to ground a receptacle? Not necessarily. Some receptacles are self grounding. You could use a self grounding receptacle and attach it to a grounded box and would be fine.
250.146 says that an equipment bonding jumper shall be used to connect the grounding terminal of a grounding type receptacle to a grounded box unless, it is a surface mounted box where you have direct metal to metal contact between the device yoke and the box.

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