Proper Grounding

[jdsac]

When Romex is being run in the walls (not exposed) to metal boxes on the studs, do the boxes have to be grounded too? Or is the ground at the recepticle enough?
Everything but the recepticles will be covered by drywall & they will have
plastic plates , so except for the screw heads, no exposed metal.
Just want to do it correctly.

Thank You for the help!

 

[MrMark]

I don't know code wise, it may be OK if you use self grounding outlets, but I would never do what you propose. It is sloppy and how hard is it to leave one ground wire running long and wrap it around a screw in the box before either pigging the ground or running it to the device?

 

[zmaxmotorsports]

It should be bonded to the box also with a ground screw.

 

[theoldwizard1]

It should be bonded to the box also with a ground screw.

That's the "new school" way. Wrap the ground around the romex clamp screw and leave enough to connect to the green screw.

 

[LXCam]

Code requires you ground the box and the device.

 

[sberry]

Does it if the device is screwed to the box?

 

[Zeke]

Does it if the device is screwed to the box?

Yes because a threaded fitting is not an allowed ground path. The ground wire must be under a ground screw against the metal surface and again under the device ground screw.

 

[wyliesdiesels]

Does it if the device is screwed to the box?

If the device is not self grounding, then yes, the metal box needs to be grounded. Personally, i would ground the box anyways. And dont forget an NM-b clamp at the box....

There is quite a few threads about this topic....

 

[Charles (in GA)]

The vast majority of receptacles are self grounding, as evidenced by the shiny metal clip or the spring wire, that contacts one of the mounting screws.

In the pic below, look at the RH receptacle, lower mounting screw. See the shiny piece of metal riveted to the yoke? That is the self grounding clip. Note the LH receptacle, the cheapie does not have this.

Another view of the shiny metal clip.

On the receptacle below, look at the mounting screw on the far right. Note the ends of wire poking out of the yoke near the screw head. This is a single piece of wire that contacts the screw. This is another version of a self grounding receptacle.

All of this being said, you are best to wrap the ground wire ¾ of the way around the ground screw in the box and continue it on to the ground screw on the receptacle. On switches you must do this, as there are no self grounding switches, and switches are required by code to have the ground screw terminal now.

Other option is to run ground wire to the ground screw in the box, and use grounding jumpers with U terminals on them for the box to receptacle/switch connection.

Charles

 

[jdsac]

Thanks for the help! I wasn't trying to cut corners. Went back & added
a ground to the box as well as to the recepticle. Learning curve, figured if in doubt- ask.

 

[monkeybar]

Here's yet another thought. Grounding and neutral wire use. Used to be, if you bought the sheathed cable normally used to hook up an electric stove, it had 4 conductors: red, black, white, green. Then, you looked at the friggin' plug on the stove, and it had 3 prongs! So what did the "electricians" do? Connected BOTH white and green to the green receptacle terminal. Was this "kosher"?

Hell, no, because it provided TWO paths for 120 volt current flow back to the meter (source). SOME just cut off the green conductor, and didn't use it at all! Granted, the 120 volt requirement was small, a clock, timer, etc. The PROBLEM though, was that you had a GROUND conductor carrying current, which is an UNACCEPTABLE ELECTRICAL CONDITION. Likely hundreds of thousands, maybe millions, of homes thus mis-wired. monkey

 

[wyliesdiesels]

Here's yet another thought. Grounding and neutral wire use. Used to be, if you bought the sheathed cable normally used to hook up an electric stove, it had 4 conductors: red, black, white, green. Then, you looked at the friggin' plug on the stove, and it had 3 prongs! So what did the "electricians" do? Connected BOTH white and green to the green receptacle terminal. Was this "kosher"?

Hell, no, because it provided TWO paths for 120 volt current flow back to the meter (source). SOME just cut off the green conductor, and didn't use it at all! Granted, the 120 volt requirement was small, a clock, timer, etc. The PROBLEM though, was that you had a GROUND conductor carrying current, which is an UNACCEPTABLE ELECTRICAL CONDITION. Likely hundreds of thousands, maybe millions, of homes thus mis-wired. monkey

If the stove feeds off a main service panel, then its not so much of an issue. But even then, an issue can arise if the neutral wire develops a bad connection and the return current then finds an alternate path such as someone touching the range chassis and a water pipe/faucet(rare though!!)

 

[JoeFin]

The vast majority of receptacles are self grounding, as evidenced by the shiny metal clip or the spring wire, that contacts one of the mounting screws.

Charles

Yes they are "Self-Grounding" - but I have yet to see an electrical / building inspector "Buy-Off" on the Electrical Rough inspection without each and every metal box having a grounding pigtail in them ...

 

[monkeybar]

If the stove feeds off a main service panel, then its not so much of an issue. But even then, an issue can arise if the neutral wire develops a bad connection and the return current then finds an alternate path such as someone touching the range chassis and a water pipe/faucet(rare though!!)

It seems today they tend to provide and use a socket and stove plug having 4 terminals instead of 3. In any event, if the neutral conductor is connected to "ground" in more places "downstream" of the original service supply point, 2 paths exist for neutral current flow, and those ground conductors (green) will be then carrying part of (1/2, if the same size conductor) of the neutral current. This can pose a serious shock hazard anywhere that's occurring, as a GREEN conductor carrying current, other than a quick fault perhaps, will have voltage dropped along it's length with respect to actual ground.

I hope I make sense! monkey

 

[wyliesdiesels]

It seems today they tend to provide and use a socket and stove plug having 4 terminals instead of 3. In any event, if the neutral conductor is connected to "ground" in more places "downstream" of the original service supply point, 2 paths exist for neutral current flow, and those ground conductors (green) will be then carrying part of (1/2, if the same size conductor) of the neutral current. This can pose a serious shock hazard anywhere that's occurring, as a GREEN conductor carrying current, other than a quick fault perhaps, will have voltage dropped along it's length with respect to actual ground.

I hope I make sense! monkey

And that is because code has changed and 3-wire 120v/240v receptacles are no longer allowed!

 

[Norcal]

That's the "new school" way. Wrap the ground around the romex clamp screw and leave enough to connect to the green screw.

Not a reliable method, nor is a NM cable connector listed for grounding.

 

[sberry]

Yup, a guy should buy a box of ground screws right off the bat. I should score some green solid wire but insulated wire is nice for pigtails. A box of spades for stranded. Half the reason people don't do this correctly is they never have the materials.

Personally with romex prefer a non metallic box.

 

[ishiboo]

Yup, a guy should buy a box of ground screws right off the bat. I should score some green solid wire but insulated wire is nice for pigtails. A box of spades for stranded. Half the reason people don't do this correctly is they never have the materials.

Personally with romex prefer a non metallic box.

Spades are the way to go. Unfortunately even the nice backwire outlets still usually have a regular ground screw, though some now I see have a hold down piece of metal under the ground screw where you can insert a straight wire and clamp down.