[hagjr]

My 1950's home has an ungrounded receptacle in the kitchen where I will be placing a new dishwasher.


(See attachment Existing Circuit)

I was trying to add a grounding conductor by running a new 12-2 NM w/Ground from the panel to the kitchen in the attic and then down the wall. Unfortunately, the wires are embedded in the concrete block without a conduit. The next downstream outlet is daisy chained to this outlet and all of the cables are accessible in the attic...I just can't pull a new cable in the concrete block wall.

I was wondering if (since there are actually 4 copper conductors in the wall for this outlet) if I could "re-purpose" one of the conductors of the daisy-chained pair and take the other conductor of the pair "out of service".

If I cut the existing cables and install 2 new junction boxes in the attic, I can make the connections and continue the downstream circuit to the next outlet (which I do not have to have grounded).

(See attachments Cut Cables and Proposed Circuit)

Is this a safe/reasonable plan? Does the NEC prohibit this for any reason? Are there any pitfalls to look out for?

I really appreciate any help you can give.

 

[Jim Port]

You can extend a grounding conductor from the other circuit.

 

[surferdude2]

The NEC 300.3 requires all conductors to be in the same conduit except under certain exceptions. I don't think you meet any of the exceptions.

It is not code compliant to cord/receptacle connect a dishwasher unless it's a portable unit. You should wire it direct from a wall junction to the junction on the fixture.

 

[Wiredindallas]

As long as you remark the now ground conductor such as by stripping the insulation, I see no problem. If it is by the sink, you might run a wire from the water pipe to the receptacle if you have metallic water lines all the way back to underground.

 

[Jim Port]

Dishwashers can be cord connected under the NEC. They do not have to be portable units. The receptacle should be accessible.

Article 250.130(C) allows the ground to extend from other areas and to not be run with the circuit conductors. You cannot ground to water pipes.

 

[Old Thomas]

Ground can be run separately from the other conductors. If it has access to outside, I would drive a ground rod outdoors and ground it. Not sure if that is compliant (my NEC is at my other place) but as long as it is not grounded in two places it should be ok.

 

[surferdude2]

The water pipe may be allowed now. See what you think about (1) and (2) since the water pipe is part of that GEC system. I'm behind on residential code. I see now that it's allowed to get a ground for upgrading an old 2 prong receptacle from several sources. According to 250.130(C) the following are allowed:

(1) Any accessible point on the grounding electrode system as described in 250.50

(2) Any accessible point on the grounding electrode conductor

(3) The equipment grounding terminal bar within the enclosure where the branch circuit for the receptacle or branch circuit originates

(4) An equipment grounding conductor that is part of another branch circuit that originates from the enclosure where the branch circuit for the receptacle or branch circuit originates

(5) For grounded systems, the grounded service conductor within the service equipment enclosure

(6) For ungrounded systems, the grounding terminal bar within the service equipment enclosure.

 

[surferdude2]

Ground can be run separately from the other conductors. If it has access to outside, I would drive a ground rod outdoors and ground it. Not sure if that is compliant (my NEC is at my other place) but as long as it is not grounded in two places it should be ok.

.
That's what I thought until I saw this: (credit due to mikeholt.com)

Perhaps there is an exception to that... it's getting to where you need a Philadelphia lawyer to devine the code and all the new changes and exceptions.

 

[Jim Port]

Ground can be run separately from the other conductors. If it has access to outside, I would drive a ground rod outdoors and ground it. Not sure if that is compliant (my NEC is at my other place) but as long as it is not grounded in two places it should be ok.

Ground rods have nothing to do with providing an equipment ground and will not provide a means to trip a breaker.

 

[Jim Port]

The connection would need to be made within 5 foot of the metallic waterline entering the building.

 

[surferdude2]

So, anywhere on the metal water line in the building and outside up to 5' from the entrance point of the u/g metal water pipe would be a point of connection for attaching an Equipment Grounding Conductor source for upgrading an existing ungrounded circuit.

If I interpret that correctly, the OP can use an approved ground clamp on the water pipe under the sink and run a #12 green wire from there to the new grounded receptacle's ground screw (and box if metal) and be code compliant. Then that ground could be used for any other receptacles under there to upgrade them.

 

[AllanJ]

If you drive a ground rod and use it for grounding anything that is powered by the building electrical system then that rod must be bonded to the other ground rod(s) already used as grounding electrodes about the building using #6 or heavier copper wire run outdoors as much as possible. If the new ground rod is the first then the copper wire must go to the first panel, to the neutral bus bar for a service panel or the ground bus bar for other panels.

When this is done then the aforementioned copper wire is a grounding electrode conductor. Separately run ground wires (equipment grounding conductors) of otherwise ungrounded branch circuits may attach to it..

Plumbing does not ordinarily qualify as part of an equipment grounding conductor. But a separately run EGC may be attached to that part of a pipe that is a grounding electrode, notably to the 5 or fewer foot section of the pipe between the proper attachment of the GEC and where the pipe exits the building underground.

 

[FrodoOne]

Ground rods have nothing to do with providing an equipment ground and will not provide a means to trip a breaker.

In fact, using a separate Equipment "Ground" rod not tied to the main System/Equipment "Ground"/(Neutral) connection is one of the worst things you could do.

(See

,
at many points, including 34:50 to 36:00 and 45:00 to 48:00)

 

[Jim Port]

The connection cannot be made under the sink to ground the receptacle. It needs to be within 5 foot of enter of the building.

 

[hagjr]

Thank you to all! As I understand from your responses:


1. I can use the proposed circuit even though the receptacle's EGC will not be within the same cable as the receptacle's hot & neutral conductors because the NEC 300.3(B) requirement has an exception 300.3(B)(2) for my 250.130(C) situation here.


2. I should mark the re-purposed white conductor with green electrical tape on both ends to signify that it is now a ground wire.

 

[Old Thomas]

Ground rods have nothing to do with providing an equipment ground and will not provide a means to trip a breaker.

So you are telling me that if I short circuit a hot wire to a properly grounded rod it will not trip a breaker? Since when?

 

[Jim Port]

Ground rods have nothing to do with providing an equipment ground and will not provide a means to trip a breaker.

So you are telling me that if I short circuit a hot wire to a properly grounded rod it will not trip a breaker? Since when?

Since forever. Using Ohms law and
25 ohms resistance you will flow 4.8 amps from a hot connected directly to a ground rod.

 

[Luke M]

So you are telling me that if I short circuit a hot wire to a properly grounded rod it will not trip a breaker? Since when?

25 ohms is considered good for a ground rod, and that only yields 120/25=4.8A, not nearly enough to trip a breaker.


(It would trip a GFCI breaker, but relying on GFCI is not allowed by the NEC).

 

[AllanJ]

Should a properly driven but stand-alone ground rod and/or wires and objects connected to (bonded to) it and not connected to other grounded objects become energized, the resulting current (called fault current because it flows due to an unwanted connection) seeks to return to its source. That is, to the pole transformer which is (should be) bonded to a rod at the base of that pole or nearby pole. To get there, the fault current has to go through the ground (as in dirt, earth, soil) between the two aforementioned ground rods. The dirt is not a very good conductor so only a small amount of current will actually flow (see Ohm's law preceding). Almost never more than 5 amperes, but consider that twenty milliamperes can electrocute someone.

Furthermore, given the resistance of the soil in the above example, the voltage between the stand alone ground rod and the real house ground can be significant, enough to result in electrocution if someone touches that stand alone rod or objects bonded to it and also the completion of a different ground path such as partially on the surface of a wet floor.

When the newly driven ground rod is properly bonded (has an essentially resistance free connection) to the grounding electrode system, then despite any fault current from unwanted energizing, the voltage of objects bonded to that rod relative to house ground will be near zero resulting in negligible electrocution hazard or the breaker will trip, stopping the fault current.

 

[FrodoOne]

So you are telling me that if I short circuit a hot wire to a properly grounded rod it will not trip a breaker? Since when?

See the video referenced in Post #13