Old two wire recep question.

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J.P.

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Location
United States
I had a project manager ( mechanical co ) ask me today if it was ok.....

On a old two wire conductor and recep to replace the recep with a three wire recep and just jump the ground post to the neutral screw . The reason being that the neutral wire went back to the panel anyway and would work just as good as a ground.

He said a old electrician told hime this. Was that ever a deal years back?

I have seen some interesting things, but not this.
 

Ponchik

Senior Member
Location
CA
Occupation
Electronologist
NO!!

you can not connect the grounding post of the receptacle to the neutral post.
 

GoldDigger

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The NEC specifically provides rules for replacing existing two wire receptacles. The most commonly used alternative is to install a three wire GFCI receptacle with no connection to the ground pin and a supplied label that states that.
 

J.P.

Senior Member
Location
United States
I know what you are supposed to do. I am just curious.

I was wondering if at one time it was common practice to jump the ground to the neutral. Kind of like it was common practice to put the receps in with the ground pin up.
 

GoldDigger

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I know what you are supposed to do. I am just curious.

I was wondering if at one time it was common practice to jump the ground to the neutral. Kind of like it was common practice to put the receps in with the ground pin up.
It was never, AFAIK, legitimate to do what your old electrician described. But it was probably done often enough, either by a lazy electrician or a homeowner or handyman.
The result of that practice, among other things, is to put between half and full line voltage on exposed metal surfaces in almost any equipment fault condition.
In the specific case of an open neutral you get full line voltage on "ground" and no breaker trip. :(
 
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I don't think it ever was "common practice". What would be the advantage to jumper to ground terminal?

The only reason anyone does this is A) they're an idiot, or B) they have some kind of inspector who will be testing the receptacles

It's not like a 3 prong won't work if it doesn't provide EGC
 

al hildenbrand

Senior Member
Location
Minnesota
Occupation
Electrical Contractor, Electrical Consultant, Electrical Engineer
I had a project manager ( mechanical co ) ask me today if it was ok.....

On a old two wire conductor and recep to replace the recep with a three wire recep and just jump the ground post to the neutral screw . The reason being that the neutral wire went back to the panel anyway and would work just as good as a ground.

He said a old electrician told hime this. Was that ever a deal years back?

I have seen some interesting things, but not this.
Over my career, I have found a few receptacle devices that I've loosened from the box, that have, in fact, been jumpered from the device ground terminal to a neutral terminal screw.

The general requirement that all receptacles installed be of the grounding type came with the adoption of the 1962 NEC, as written. Prior to the 1962 NEC, grounding type receptacles were required in specific situations (kind of like GFCIs are required now in specific situations). The Main Bonding Jumper tie together of Neutral and Equipment Grounding Conductors (EGCs) at the Service Disconnect is much older than the 1962 NEC.

What your Project Manager asked about has never been "a deal." It has only been non-Code wiring.

GoldDigger does a good job of indicating the Hazards of installing this jumper.
 

growler

Senior Member
Location
Atlanta,GA
On a old two wire conductor and recep to replace the recep with a three wire recep and just jump the ground post to the neutral screw . The reason being that the neutral wire went back to the panel anyway and would work just as good as a ground.

He said a old electrician told him this.



The problem is that almost anyone can claim to be an "electrican". I looked at a job done by an old electrican not long ago. I would guess that he had never really been trained and never opened a code book but I believed he had been doing electrical work off and on for 40 years ( none of it safe).

I have seen many bootleg grounds and many where they just installed the 3-prong receptacle without ground (or GFCI protection).

Some people don't know what they are doing is wrong and others just don't care.
 

ATSman

ATSman
Location
San Francisco Bay Area
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Electrical Engineer/ Electrical Testing & Controls
The NEC specifically provides rules for replacing existing two wire receptacles. The most commonly used alternative is to install a three wire GFCI receptacle with no connection to the ground pin and a supplied label that states that.

Ok, but if the wiring is knob & tube with no ground conductor or EMT, how will that detect a ground fault?
 

GoldDigger

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Location
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Ok, but if the wiring is knob & tube with no ground conductor or EMT, how will that detect a ground fault?
If the current on the hot does not cancel the current on the neutral, there must be a ground fault present. No access to an EGC is needed for detection.
Since there is no EGC to the equipment, the fault current will be following some other path, such as through water pipes or through a user to "earth".
 
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al hildenbrand

Senior Member
Location
Minnesota
Occupation
Electrical Contractor, Electrical Consultant, Electrical Engineer
The NEC specifically provides rules for replacing existing two wire receptacles. The most commonly used alternative is to install a three wire GFCI receptacle with no connection to the ground pin and a supplied label that states that.
Ok, but if the wiring is knob & tube with no ground conductor or EMT, how will that detect a ground fault?
A standard Class A GFCI doesn't us an EGC in anyway to provide ground fault detection.
 

charlie b

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Location
Lockport, IL
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Retired Electrical Engineer
Ok, but if the wiring is knob & tube with no ground conductor or EMT, how will that detect a ground fault?
A GFCI device looks for differences in the currents flowing in the ungrounded ("hot") conductor and the grounded ("neutral") conductor. If they are different by as little as 3 milliamps, it will trip. It does not need an equipment grounding conductor in order to perform that function. So if there is any leakage current through planet Earth back to the source, the GFCI will detect it, and will trip.

 

charlie b

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Location
Lockport, IL
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Retired Electrical Engineer
Kind of like it was common practice to put the receps in with the ground pin up.
There is no reason that could not be a common practice, for it is as legal and safe as any other direction. I wanted to correct your statement, but having done so I will mention that this is a forbidden topic on the forum (because it has been beaten to death often enough). Please see our FAQs for more information.

 

ATSman

ATSman
Location
San Francisco Bay Area
Occupation
Electrical Engineer/ Electrical Testing & Controls
If the current on the hot does not cancel the current on the neutral, there must be a ground fault present. No access to an EGC is needed for detection.

Bear with me but having a hard time visualizing this. This subject has to do with "net current."
Where is the path for the GF current to return to the source (branch panel) when the fault occurs?
Are you saying that it finds a path thru building steel or some other metal structure.
Can you reference a MH article to explain this?
Tks
 

charlie b

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Location
Lockport, IL
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Retired Electrical Engineer
The reason being that the neutral wire went back to the panel anyway and would work just as good as a ground.
Suppose you are driving from one place to another, intending to be present at some event. Suppose you see a couple guys in dirty clothes, smoking and with open bottles of booze, with their thumbs out hitching for a ride to the same event. Would you want to give them a ride, under the reasoning that you are going to wind up at the same location anyway? :happysad:

Actually, I just thought of that analogy as I was reading this thread. What do you think of it? :)

My real answer is that the equipment grounding conductor is intended never to anything at all, not for its entire operational life, unless and until there is a fault. Then it will do its one and only job, which is to carry the fault current back to the source, so that the circuit breaker will see that large fault current, trip, and thus terminate the event. We don?t want the ground wire to do anything else, and certainly not to carry current on a normal basis. :thumbsdown:
 

al hildenbrand

Senior Member
Location
Minnesota
Occupation
Electrical Contractor, Electrical Consultant, Electrical Engineer
Bear with me but having a hard time visualizing this. This subject has to do with "net current."
Where is the path for the GF current to return to the source (branch panel) when the fault occurs?
Are you saying that it finds a path thru building steel or some other metal structure.
Can you reference a MH article to explain this?
Tks
Since the GFCI is a device designed for Safety of Personnel, the ground fault is assumed to be passing through the body of who ever is in contact with the hot to neutral conductor path, and, in turn, is passing from the person's body into what ever they are in contact with that causes their body to be a conductor.
 

charlie b

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Staff member
Location
Lockport, IL
Occupation
Retired Electrical Engineer
Where is the path for the GF current to return to the source (branch panel) when the fault occurs? Are you saying that it finds a path thru building steel or some other metal structure.
Let's clarify what we mean by "ground fault." Current normally flows from the panel, through the hot wire, to and then through the load, and via the neutral wire back to the panel. Suppose you are using a metal tool, and it is plugged into a receptacle that has no ground wire. Suppose that internal to the tool, a wire breaks loose and comes into contact with the metal case. The tool may still be operational, and the normal current path described above may still be available. But now there is a second path for current to flow. It starts the same way: from the panel, via the hot conductor, to the tool. Inside the tool, current will now flow through the broken wire, to the case of the tool, to the hand of the person holding the tool, through that person's body to the floor, then into the dirt below the floor. From there, current flows through planet Earth (and yes, the planet is a good conductor of electricity) to the location of the building's grounding electrode system (e.g., the ground rod), then up the grounding electrode conductor to the panelboard's N-G bond point. Thus, the second path of current is now complete, and current has returned to its source. This is one example of a "ground fault."

But take note that the current in the hot conductor and in the neutral conductor are not equal. The GFCI device will notice the difference, and will trip.

 
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