Adding a ground wire to 2 conductor wiring.

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Old 12-23-19, 06:56 AM
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Adding a ground wire to 2 conductor wiring.

Some circuits in my house are 2 conductor wire in very good condition.

1) Can I add a grounding wire from the main electrical box the first junction box and then between each junction box.

2) Can I consider this 2 conductor+ ground wire a three-conductor cable and extend it? I have a single lighting fixture that was once knob and tube. It would be nicer looking if it could be added to the circuit with 2 conductor + grounded boxes. The lighting fixture is wired with romex from circuits on the upper floor in a way that is unattractive visually (wiremold conduit).
 
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Old 12-23-19, 11:02 AM
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1. yes you can
2. yes you can
 
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Old 12-24-19, 07:02 AM
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Thank you for answering my questions.

Are there any rules to the ground wire?

1) Can I attach the ground wire to the outside of the box with a screw?

For example, instead of disconnecting a lighting fixture to work inside the box can I from above the box screw a grounding wire to the box? I will later test each lighting fixture to determine if it is grounded.

2) Can a ground wire be exposed uninsulated wire?

3) Can multiple ground wires be joined outside an electrical box?

Inside a crawlspace can I connect multiple ground wires with a twist nut outside of any junction box?

4) Can a junction box be grounded to more than one circuit?

For example, In an attic crawl space, there are 2 junction boxes on 2 different grounded circuits with 2 separate circuit breakers. Can a ground wire be attached between those 2 junction boxes?
 
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Old 12-24-19, 07:07 AM
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1. no. I has to go inside and it has to be a proper ground screw.
2. yes
3. not sure about code on that one.
4. yes. all grounds are always all connected. One ground wire from the panel can service several different circuits. It must be sized to the largest circuit.
A ground wire doesn't have to go back to the panel. It can go to any other point on grounding system that has the same gauge or larger wire.
 
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Old 12-24-19, 07:13 AM
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3) Can multiple ground wires be joined outside an electrical box?
Any splice is required to be inside a box and the box is required to be accessible. The only exception would be low voltage wiring.
 
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Old 12-24-19, 08:27 AM
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I have to ask because I am not clear about what wiring you have. Is it old 2 wire romex without a ground? If so you cannot add a ground wire independent of the cable. If the wiring is individual wires in a metal conduit system you can pull a ground or use the conduit as a ground.
 
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Old 12-24-19, 08:31 AM
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Is it old 2 wire romex without a ground? If so you cannot add a ground wire independent of the cable.
That is not correct. See below.



300.3(b)

2) Grounding and Bonding Conductors. Equipment grounding conductors shall be permitted to be installed outside a raceway or cable assembly where in accordance with the provisions of 250.130(C) for certain existing installations or in accordance with 250.134(B), Exception No. 2, for dc circuits. Equipment bonding conductors shall be permitted to be installed on the outside of raceways in accordance with 250.102(E).
 
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Old 12-24-19, 12:57 PM
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It has been ages since having to deal with old wiring. I just had 300(B) only in my head. I had forgotten about the "unless otherwise permitted" in (2). Thanks for the correction.
 
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Old 12-26-19, 11:12 AM
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Picture, no question but it looks like the ground is uninsulated copper.

250.130(C) Nongrounding Receptacle Replacement or Branch Circuit Extensions.



https://www.electricallicenserenewal...sectionID=52.0
 
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Old 12-26-19, 07:10 PM
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The ground can be bare or insulated.
 
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Old 12-27-19, 06:08 AM
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Reminder, if the box is metal, it needs to be grounded, as does the device.

There are some which are self-grounding (has a metal clip holding one of the screws in rather than a paper washer). These require only the device OR the box to be grounded.
 
 

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