Outlet box grounding

How many of you ground the metal outlet box and the outlet? I have always grounded both just to be safe but got to thinking last night if it is necessary. The box would be grounded when the outlet is installed and the only time the outlet would be unhooked from the box, the power should be shut off anyhow. Just wundering if I needed the extra grounding or not.

T I A
Brad

When I was an electrical design engineer I always specified BOTH (Metal Box & Receptacles Green Grounding screw) were to be connected to a Green/Bare Equipment GroundING Conductor. Our electricians used the little braded wire grounding pigtails with the green screw to ground the metal box and sometimes used greenies with the green wire nut having the hole out the top for splicing all the ground wires together with the extra long wire out the top to attach to the Green Ground screw on the receptacle itself (or vice versa to the receptacle). NOTE there are other ways to accomplish the same, but regardless I would somehow attach BOTH the metal box and the Receptcles own Green Grounding screw to GroundING Conductors even if only one were used a contact between the receptacles mounting strap and the metal box is present. But that's just me and my years ago NEC training as I best recall it IE GROUND BOTH

Sure Billy Bob, if EITHER the metal box orrrrrrrr the Receptacles green grounding screw are grounded, those two get connected together when the receptacles metal mounting strap screws into the box, and yes Bubba that can work to bond both to the Equipment GroundING Conductor BUT FEEL FREE TO DO AS YOU PLEASE.

Also consult with local authority or the Utility as to what they require (NONE of us here)

NOTE This, like all other posts here (Electrical and Legal questions always draw plenty of opinions) IS ONLY MY OPINION with NO warranty, it may be right and it may be wrong, I'm NOT saying if it is or it isn't, I'm ONLY saying that's how I did it when and where I was a design engineer. Yall wire anyway you please.

John T Too long retired Electrical Engineer and rusty as an old nail on the latest codes, so some may agree with this and others may not, lets see lol

I guess I was trained to ground both like
John T says. Never checked to see if it
was code or not, just seemed right. Good
to see John is still around, I haven't
seen any posts from him lately.

I'm going to add a couple outlites in my barn. I was going to take two short pieces of ground wire, one to the steel outlite box and one two the outlite. Then wire nut them to the incoming ground wire. I don't know allot about it but I assume that would be one way to do it. Correct me if I'm wrong?

John I respect most all of your posts on electrical subjects.

Buuuttt isn"t grounding a steel box that has a properly grounded receptacle in it about like putting a tube inside a tube in a tire. If one gets a hole in it the other is most likely going to get a hole as well.

Seems like a waste of time and wire to me.

I put a new service in about 2 years ago for my drying bins. When the inspector came to look I had used a plastic nut on the steel pipe nipple between the meter socket and the main disconnect.

I did not want the wires to get skinned on the nipple and did not have enough threads to locknut it and plastic cap.

He said I should have used steel nut to bond the boxes together. He was going to make me pull those 4o wires back out and put on steel.

I said wait a minute, my frame the boxes are all mounted on is steel and bolted together. And besides I could have use a plastic nipple and it would have passed as well.

He could not argue with me and passed it.

Just my thoughts.

Gary

The correct method is to ground both, I get lazy once in a while and skip it.

In this corner of the world the inspectors say the same thing. They want to see any rigid conduit with a grounding bushing on one end, or PVC. Since a bushing is $10 plus higher priced steel conduit most people go to PVC which, IMHO, is not as safe as metal conduit.

Just had to ground the outlets for a friend because the screws holding the outlet in metal box with PVC tubing kept popping the GFI. They worked for a few months. I have always done both.

Code is to pigtail the ground in the box. Ground the box and
receptacle .
Code also doesn"t trust conduit as a ground path . A ground
wire must be pulled with the power wires.

Not trying to answer the question for john, just relating a similar experience.

In short if it is metal you ground it. The 6-32 screw on the receptacle is not always a legal ground. joe

Kinda nit picking here.

So if it is a metal box with a metal cover over the receptacle, do you ground the cover as well?

I know being a smart azz.

Gary

Hey Gary, no problem and I enjoy sparky chats...As I said if EITHER the metal box orrrrrrrrr the receptacles green grounding screw is grounded then BOTH are grounded due to the fact the receptacles metal mount strap is electrically connected to the green grounding screw BUT BEST I RECALL FROM MANY NEC UPDATE SEMINARS THATS NOTTTTTTTTTT PERMISSIBLE.

Now I could be wrong and its been yearssssssss since I attended those every three years (when a new code was published) NEC Update Seminars, but I seem to recall Joe McPartland and Mike Holt (true NEC experts) preaching that was best and proper and NEC required.

BUT THINK ABOUT IT Its easy to imagine the two small top and bottom receptacle mounting screws getting loose in which case there could be a resistive ground connection orrrrrrrrr if the box ground screw is loose and a short is to the box (easy to happen) there could be a resistive link and if theres no attachment right to the receptacles green grounding screw the circuit may not have a good ground. If you don't ground BOTH the box and receptacles screw and rely on the two loose small mounting screws one could easily end up not well grounded.

You can see where I'm coming from, I think the NEC requires it but even if it didn't I always specified a green/bare equipment grounding conductor be properly attached to BOTH the box and green receptacle screw as otherwise youre relying on a couple weak and easy to come loose small top and bottom screws

THATS WHY I PREFER BOTH BE DIRECT GROUNDED that's my story n Ima stickin to it (and think the NEC agrees)

Thanks Gary, fun chatitn at ya

John T

I just use plastic outlet boxes

buickanddeere,

Not offering a challenge to your opinion, but I have a 2008 NEC and would like a reference to further educate me.

I think the outlet needs a pigtail, but I am of the thought that believes a recognized metallic conduit qualifies as a grounding conductor, with some limitations.

thanks,

D.

(quoted from post at 20:20:14 02/18/14) buickanddeere,

Not offering a challenge to your opinion, but I have a 2008 NEC and would like a reference to further educate me.

I think the outlet needs a pigtail, but I am of the thought that believes a recognized metallic conduit qualifies as a grounding conductor, with some limitations.

thanks,

D.

Click to expand...

Didn't we go thru the whole metallic conduit as a ground thing a couple of weeks ago?

IH2444,

I wasn't part of that discussion, could you give me the rundown?

D.

I do not remember exactly how it turned out on the EMT conduit as related to the NEC, but most agreed it was not a good thing to count on EMT as a bonded ground. Rigid however is another matter and provides good thru grounds.

I always run a separate ground thru EMT.

Perhaps someone better at memory or searching for threads can post info/link to the thread.

IH24444,

As far as I have been told, most areas accept the NEC in it's current form as OK. Maybe not the best, but is an OK way of doing electrical.

I do not want to try anyone's patience or experience. I'd rather read it for myself and then gather my own opinion.

I prefer references to an almost universally accepted doctrine.

D.