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This is a follow-up to this question.

I am adding (outlets) on to a 2-wire 12AWG (no ground) circuit and I want the new outlets grounded. Can I run a ground wire to the panel along the outside of the house? Obviously it is at greater risk of corrosion and damage than a wire run internally, but this is my only choice (other than leaving the outlets ungrounded). It seems like most ground wires I have seen from the panel to the ground rod are usually un-shielded and un-armored, but are heavy gauge and short runs.

I am thinking maybe a 10- or 8-AWG bare wire run under the eaves would be the easiest/best (however ugly) solution. Total run would be about 30 feet. All suggestions, warnings, or scoldings are welcome.

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    Call an electrician to come take a look. The cost for a new (grounded) circuit might be cheaper than you expect (depending on location).
    – Tester101
    Commented Dec 12, 2011 at 20:26
  • @Tester101 I have no attic or crawlspace. replacing the circuit involves removal and repair of 1-in thick sandy plaster in 3-4 rooms on two levels. Remodeling these rooms is planned future work in the next decade or so, but not now.
    – Paul
    Commented Dec 13, 2011 at 19:22
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    I don't know what to tell you... a good installer will be able to pull new cable with limited damage, but there likely will be damage. As for running a ground outside to the panel, I'm going to say that's a definite no. Why are GFCI's not an option?
    – Tester101
    Commented Dec 13, 2011 at 19:38
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    Can you run a new exterior circuit (in conduit)?
    – Steven
    Commented Dec 14, 2011 at 15:36

4 Answers 4

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National Electrical Code 2014

Chapter 3 Wiring Methods

Article 300 Wiring Methods and Materials

I. General

300.3 Conductors

(B) Conductors of the Same Circuit. All conductors of the same circuit and, where used, the grounded conductor and all equipment-grounding conductors and bonding conductors shall be contained within the same raceway, auxiliary gutter, cable tray, cablebus assembly, trench, cable, or cord, unless otherwise permitted in accordance with 300.3(B)(1) through (B)(4).

The hot and neutral wires should be in the same raceway to reduce Inductive Coupling. You'll see using the Right-hand rule, that the magnetic fields created by the hot and neutral wires tend to cancel each other out. Thereby reducing the affects of inductive coupling.

enter image description here I = current flow direction. B = direction of the magnetic field.

enter image description here

The ground wire was required to run in the same raceway, to provide a safe path for electricity to travel in the event of a short. If one of the wires sheathing becomes damaged, it's likely the exposed wire would have come in contact with the ground. The same way an equipment ground provides protection at a consumer, running the ground in the same raceway provides similar protection the entire length of the circuit.

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While, technically, running an EGC separately from its circuit is allowed by code as of the 2014 NEC as per 250.130, paragraph 2:

For replacement of non-grounding-type receptacles with grounding-type receptacles and for branch-circuit extensions only in existing installations that do not have an equipment grounding conductor in the branch circuit, connections shall be permitted as indicated in 250.130(C).

250.130(C):

(C) Nongrounding Receptacle Replacement or Branch Circuit Extensions. The equipment grounding conductor of a grounding-type receptacle or a branch- circuit extension shall be permitted to be connected to any of the following:

(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

and 300.3(B)(2):

(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).

I would prefer a retrofit using a GFCI or DFCI circuit breaker or GFCI receptacle as allowed for in 406.4(D)(2):

(2) Non-Grounding-Type Receptacles. Where attachment to an equipment grounding conductor does not exist in the receptacle enclosure, the installation shall comply with (D)(2)(a), (D)(2)(b), or (D)(2)(c).

(a) A non-grounding-type receptacle(s) shall be permitted to be replaced with another non-grounding-type receptacle(s).

(b) A non-grounding-type receptacle(s) shall be permitted to be replaced with a ground-fault circuit interrupter-type of receptacle(s). These receptacles shall be marked "No Equipment Ground." An equipment grounding conductor shall not be connected from the ground-fault circuit-interrupter-type receptacle to any outlet supplied from the ground-fault circuit-interrupter receptacle.

(c) A non-grounding-type receptacle(s) shall be permitted to be replaced with a grounding-type receptacle(s) where supplied through a ground-fault circuit interrupter. Grounding-type receptacles supplied through the ground-fault circuit interrupter shall be marked "GFCI Protected" and "No Equipment Ground." An equipment grounding conductor shall not be connected between the grounding-type receptacles.

because such a retrofit is much less labor-intensive for the electrician, will be safer (as someone may unknowingly unhook a separately routed EGC and fail to reconnect it, whereas a GFCI's protection is always there), and doesn't create a massive current loop in case of a low-level ground fault, with its resulting magnetic EMI and possible magnetic pickup of stray voltages and RF.

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  • This is the 2014 amendment I mentioned in Tester101's answer.
    – Harper - Reinstate Monica
    Commented Jan 10, 2017 at 2:01
  • @Harper -- indeed it is :)
    – ThreePhaseEel
    Commented Jan 10, 2017 at 2:03
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While I agree with all of the above, the direct answer to your question is, "Yes."

If you can get a ground wire to your new outlets, then they'll be grounded. The currently installed wires will not have the protection of the parallel ground wire, but the the new outlets themselves will be normally grounded.

In practical use, your ground wire will not be affected by inductive coupling, since it will carry no current.

Your installation will not meet code, so a licensed electrician is prohibited from installing it that way. But it would have met code 40 years ago, when many homes were retroactively grounded. It was considered at that time to be a perfectly safe/normal option. Only you can decide if that's good enough for your purposes.

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    `"In practical use, your ground wire will not be affected by inductive coupling, since it will carry no current."' -- That isn't true. By having a big physical separation, this method effectively makes a huge loop antenna. It will inject all manner of RF noise -- which can damage electronics and even trip GFCI devices. It's probably extra fun in a lighting storm, too. ;)
    – Brock Adams
    Commented Apr 17, 2012 at 7:38
  • @BrockAdams all of that would be true, except it's a ground wire and therefore grounded.
    – Josh from Qaribou
    Commented Apr 25, 2021 at 19:47
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by code, this is not allowed. the ground must be run in parallel for the entire run.

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    +1 if you can point to the section of the NEC (or whatever code you are referring to).
    – auujay
    Commented Dec 19, 2011 at 19:30
  • @auujay NEC 300.3(b)
    – Tester101
    Commented Dec 20, 2011 at 21:02
  • Sorry, 300.3(B) includes exceptions, and one of those exceptions is using non-ferrous wiring methods (300.20(B)).
    – Julie in Austin
    Commented Jun 16, 2014 at 17:57
  • @JulieinAustin -- you're applying the wrong exception to the OP's situation -- 300.3(B)(2) applies to EGCs, not 300.3(B)(3).
    – ThreePhaseEel
    Commented Mar 18, 2015 at 22:50

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