Am I grounded? Electrically speaking.

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Have a question on Electrical outlet grounding. Hope you guys can help me out.
I'm pretty new to Home repairs but learning fast. I had ran into a small item that I cannot seem to accept. Namely, grounding an outlet.
I had replaced an old two prong outlet with a 3 prong in the garage. The original was not grounded, obviously. I was told by the "Guy" at Home Depot that the only thing I had needed to do to ground the outlet was to connect the GREEN screw to the metal casing I had got to install the plug in. The old casing was thrown away. I got one of them industrial metal casings and screwed it to the Drywall in the garage.
For the life of me, I don't see how the outlet is grounded. The "Guy" says, as long as it is to 'metal' I'm grounded. The House is grounded with an 8 foot copper bar to the Main breaker box. But the metal box, is just to the drywall. Also am worried about arcing. The Hot lead and the Neutral are in this box, and both screws are about 1/4 inch away from the casing. Is this a cause for alarm? Should it be insulated away somehow?
On the outlet, I had connected a #8 piece of copper wire to the metal casing, and the green screw.
Am I grounded on this outlet?
Many thanks,
Chantecleer
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No. The ground needs to run all the way back to the breaker or sub panel only. No running it to a water pipe, no running it to The/A ground rod, etc. Tony D.
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Also in the garage you need a GFI.
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help me out.

small
garage. The

Home Depot

connect
in. The

casings and

"Guy" says,

an 8

to the

are in

Is this a

metal
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Well, if he puts in a GFCI, he really doesn't need a "ground" in the first place. The GFCI provides MUCH more protection than a mere ground.
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Doesn't the GFI require a good ground to work properly?

first
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No. The GFCI just measures the current difference between the hot lead and the ground lead. This has been answered time after time here.
Art Begun wrote:

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George E. Cawthon wrote:

The difference between hot and *neutral*. Ground is a good idea but irrelevant from the GFCI's perspective.
I haven't really figured out how a 220V GFCI works though (assuming there's a neutral as well as the two hot wires). I saw a 220V GFCI breaker (50A?) in a weatherproof metal box for less than $100 yesterday -- it was labelled as a disconnect for a spa, which I assume has a 110V lightbulb and maybe a timer or pump as well as the 220V heater (hence a neutral.) This sounds ideal for a temporary service at a jobsite or in a garage or something.
Bob
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zxcvbob wrote:

Another term for the neutral wire is "ground." The neutral(ground) is bonded to the green wire at the box. The green wire in older stuff (maybe still) is called the "grounding" wire.
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Neutral wire and ground wire are NOT - repeat NOT - the same. Yes they both meet a common bus in breaker box. But it is wrong and it is dangerous to advocate safety ground and neutral as same. Wire is not a perfect conductor. Electrically speaking, there is always a difference between both ends of a wire. Neutral (white) wire and safety ground wire may be electrically same at breaker box end BUT are electrically different at wall receptacle.
George E. Cawthon wrote:

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I was a bit sloppy in my terms using "ground" instead of "grounded." The NEC has and probably still calls the wire that goes which serves to replace the earth a "grounded" wire. This grounded wire is white. Some (maybe a lot of) people call it the neutral, but that's gives a false impression since in AC since current flows both ways. The wire that you call a safety ground is the "grounding" wire. I don't have a current NEC so maybe these terms have changed.
If you attach a 12/3 romex at the breaker box and a receptacle at the other line, the grounded and the grounding wire will be identical electrically identical since they are both the same size and the same length. There is no difference it how you hook appliance to the wires that is different.
w_tom wrote:

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It is wrong and quite dangerous to use the grounding conductor (ground wire) and the grounded conductor (neutral wire) interchangeably. Yes, they are connected together in the panel but that's irrelevant.
If it were okay to interchange them, there'd not be two of them.
For example: if you have the ground and neutral reversed in an outlet and you have a wiring fault, a single hot-case short in a three prong appliance can make every grounded metal surface on that circuit go live.
--
Chris Lewis, Una confibula non set est
It's not just anyone who gets a Starship Cruiser class named after them.
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Chris Lewis wrote:

No. You miss read what I wrote (mistakes included), which was that "there is no difference, it is how you hook up the appliances." You're right of course, you cannot use them interchangeably, but its no irrelevant that they are connected at the panel. I was responding to a person that said the two wires were the same electrically at the panel but electrically different at the end of the wire. That isn't necessarily true.
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The neutral and safety ground ARE electrically different. For example, with a load on hot (black) and neutral (white) wires, a voltage difference between neutral (white) and safety ground could be as much as two volts at the receptacle. Why? An important concept. Either end of wire, electrically, is not same. Wire is an electronic component; a concept that makes understanding the code easier. In some cases (ie. in this exampled, safety ground wire), electricity appears to be same at both ends of safety ground wire. In the meantime, both ends of neutral (white) wire are electrically different. Appreciate the concept to understand why code is written. Wires are not considered electrically same at both ends. Even though neutral (white) and safety ground meet at breaker box, still, they are not electrically equivalent in receptacle box.
That just for discussing electricity per NEC concerns. Then it gets even more interesting. For interconnected electronics, if a safety ground does not exist (circuit uses three wire receptacle but is only two wires protected by GFCI), then electronic damage is possible (not probably but possible). NEC does not address transistor safety. Such potential damage to interconnected electronics is beyond the scope of NEC. NEC is only concerned with human safety; not transistor safety. Yes, the GFCI can justify three prong plugs (if marked accordingly with a specific three word, NEC defined, expression). But safety ground also provides functions.
Terms such as 'safety ground' are not NEC specific. 'Safety ground' is used to make the concepts clearer for the reader. In grounding, the outlet safety ground is different from the breaker box safety ground, is different from the motherboard ground, is different from the computer chassis ground, is different from earth ground. All are interconnected. However each is a different ground with different functions. This in part because no wire is a perfect conductor.
Same reason why safety ground wire connects breaker box to water pipe (and in some jurisdictions, a ground is also made to gas pipe). It is not an earth ground. Its function is to remove electricity from pipe - for human safety reasons. Like wire, pipes are also not electrically equivalent at both ends - which is why a safety ground connection must not be made to water pipes elsewhere in the building. Pipes are no long acceptable as a place to dump electricity - even if electricity is only being dumped there during a very intermittent short circuit. Pipes must not be part of any electrical circuit - which is a relatively new concept in the code.
In the original post, noted was that neutral (white) wire and safety ground wire are not same. Proof. Short neutral and safety ground together at receptacle on an arc faulted (protected) circuit. Build a little test plug and prove it yourself. See how long the circuit remains functional. Any short between safety ground and neutral will (eventually) trip an arc fault breaker because neutral and safety ground wire must remain completely isolated; except in breaker box.
Demonstrated by experiment - and so many reasons above - the neutral (white) wire and safety ground wire are electrically different everywhere except where they meet in breaker box.
George E. Cawthon wrote:

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I don't disagree with what you are saying, and I don't want to belabor my point. Maybe I am being too esoteric or maybe I read what you said wrong, but my intent was very narrow case. You said, "Neutral (white) wire and safety ground wire may be electrically same at breaker box end BUT are electrically different at wall receptacle." I took that to mean that at the receptacle the white wire was electrically different compared to safety ground. I know that they are electrically different at the receptacle compare to the breaker box end. My point was that as long as nothing is connected to or operating on that cable, there is no difference between the two wires at any point along the cable since they are both the same size and the same length. You discussion is about operating appliances and the function of each wire, and I don't have any argument with that.
w_tom wrote:

I don't have an arc fault protected circuit to test that and I'm not sure how an arc fault protector work. However, I realize that connecting the two at any point makes a parallel path, so any load upstream will send half the current down each wire to the breaker box. If an arc fault protector measures current to the grounding wire, that's a no brainer and not testing is needed. You are simply putting current into a wire that is not supposed to have any current except when something goes wrong. All this is good, but it has nothing to do with what I said. I did not say that you could use either wire, white or green (bare), for a specific function. You cannot interchange the wires or you screw up or loose the function of one or both wires.

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It _usually_ is different electrically.
The neutral wire will carry current when anything on the circuit is in use. From ohms law, then, the voltage on the neutral will _not_ be zero. It could be as high as 7 volts (and that's with everything working as it should).
This can cause problems if it's connected to the grounding system, or even if it's improperly used as the ground on a single outlet.
--
Chris Lewis, Una confibula non set est
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George E. Cawthon wrote:

The National Electrical Code uses the term "grounded conductor" (not "ground") for the neutral, and "grounding conductor" for the green or bare safety ground wire.
--
--
Steve

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Steve Dunbar wrote:

Right I was sloppy leaving the "ed" off the end.
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That "guy" at HD is fixin' to kill someone some day if he's dispensing that kind of helpful advice. I'm pleased you were sharp enough to question what he told you here.
BTW, a quarter of an inch is plenty of spacing between the screw heads and the box. If you want to really check it out, turn off the power to that circuit and loosen (but don't remove) both of the outlet hold down screws. Then twist and push the outlet to see if either of those screws could touch the box if the screws vibrated loose.. Chances are they won't, boxes and outlets are made to accomdate the motion allowed by the slotted holes in the outlet mounting tabs. It's there to let you compensate for a minor mounting tilt of the box.
It's a nice revenge fantasy to think about writing a letter to HD about your experience, if you'd remembered the "guy's'" name.
Something like, "Joe So and So at your Podunk store told me that blah blah.....Would you please confirm this for me? Sent by certified mail, return receipt to get their attention.
Chantecleer wrote:

--
Jeff Wisnia (W1BSV + Brass Rat '57 EE)

"If you can smile when things are going wrong, you've thought of someone to blame
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True only if that metal box is grounded. What kind of method is used to bring power to this new industrial box? If it's romex (NM cable) it should have a ground wire. If it's BX (metal armored cable) the armor *used* to be considered a sufficient ground, and if it's pipe or EMT (Electrical metallic tubing) it should be grounded by a continuious metallic raceway system all the way back to the panel.

That's great but grounding the service won't ground each individual box or device.

Well if the box isn't grounded, no cause for alarm, electricity doesn't have a reason to arc to a non grounded box! Otherwise, we usually wrap a couple wraps of electrical tape around the body of the outlet, covering the terminal screws. Not really to protect from arcing though - more to prevent the spackler's knife from shorting out the outlet when he passes it over the edge of the plaster ring.

If the box isn't connected to ground, it's not grounded. Why did you use a #8?
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HA HA Budys Here wrote:
Cut the top...

I had #8 solid copper wire. So I used it. Leftover from when I bonded the Hot and Cold water pipe to the gas pipe, as the City inspector said I should. (The main box was upgraded.)
The wiring of the outlet was a conversion. It had a 30 Amp 220V plug on it that I will never use. So I converted it to a 20 Amp 110 plug. Had extra breakers in the box. This plug had 3 wires used to go to an electric dryer at 220V. I taped up the Red Hot wire and used the Black Hot and the White Neutral. It did not have any grounding from what I could see. I had put the plug into the box and it all works. But I could not believe this was grounded just because the green wire went to the metal box. I'm running the washer and dryer off it. Gas dryer.
I am replacing the plug with a GFCI. Immediately. Won't I have the same problem however? The GFCI will also just go from Green screw to the metal casing of the box. Is there something else I need to do here? I would NOT want to rewire the whole thing. I'd rather shoot it.
Thanks for all the common sense help.
Chantecleer
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