Move outlet - Old BX Armor Cable w/updated wiring

Discussion in 'Electrical Forum discussion & Blog' started by MattinLa, Sep 15, 2020.

  1. MattinLa

    MattinLa New Member

    Joined:
    Sep 8, 2020
    Location:
    Los Angeles
    I'd like to move this outlet 3ft over. As you can see my home still has the old BX armored boxes/cables; however, we have had the wiring throughout the house upgraded to new wire (all the cloth wrapped wires have been removed).

    I'd like to close off this outlet and leave the box (put a metal plate on it). Then move the outlet over about 3ft. Can I use romex and wire the ground to this original box? Or should I get new armored cable to run the new wire?

    Also it looks like the electrician that updated the wiring didn't run a ground wire, so the ground must still be relying on the metal boxes/cabling. Is that the normal way to update? I was expecting to see a ground wire when I opened this up.

    Thanks!
    Matt
     

    Attached Files:

  2. wwhitney

    wwhitney Well-Known Member

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    Location:
    Berkeley, CA
    The important question is whether your AC cable is so old that it has no bonding strip on the armor, or whether it is newer. If it has a bonding strip, it's an effective ground fault path, and you can extend the circuit with a non-metallic wiring method by connecting the EGC to the box. If the box remains, it can get a blank plate, but the plate has to be accessible, no burying it behind drywall.

    If the AC cable has no bonding strip on the armor, then in practice it's not an effective ground fault path, so your circuit is effectively ungrounded. I would advise replacing the AC cable with a wiring method with grounding conductor.

    Cheers, Wayne
     
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  4. Reach4

    Reach4 Well-Known Member

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    You can extend the wire I think, using a grounding method comparable to the suspect grounding method, but don't rely on that ground. Then put a GFI outlet in the new location. Ground not required, as long as you label the GFCI outlet "No equipment ground". Labels available. http://communities.leviton.com/thread/1080
    [​IMG]

    The dodgy equipment ground could be better than none, but not for labeling.
     
  5. wwhitney

    wwhitney Well-Known Member

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    Location:
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    That method is only allowed for receptacle replacement, not for circuit extension. And with that method, the equipment grounding conductor should not be connected at the receptacles. If it is, then a fault to case on one appliance would raise the potential of the case of another appliance. As soon as you touched one and completed a circuit, the GFCI will trip if it's working, but there's no upside to extending the hazard.

    [Edit: NEC 406.4(D)(2)]

    Cheers, Wayne
     
  6. Reach4

    Reach4 Well-Known Member

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    Location:
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    I am not sure that I would not consider this a case of receptacle replacement, but that is probably stretching. Maybe 406.4(D)(2)(c) forbids it. I am not sure.
    I am not sure what you are saying, but I think I disagree with it. I think you are saying that an unreliable ground is a danger vs having no ground at all. I think if you treat it as ungrounded, then no additional danger is introduced.

    Searching that reference lead me to https://www.electricallicenserenewa...ation-Courses/NEC-Content.php?sectionID=306.0
    That points out that
    Section 406.4(D)(2) provides options to replace the old two-prong receptacle without adding an equipment grounding conductor.​
    So Matt could ruin a separate equipment ground wire back to the breaker box, without having to remove the old wiring.
     
  7. wwhitney

    wwhitney Well-Known Member

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    Location:
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    OK, first the hazard part:

    Say you have a ungrounded circuit with multiple receptacles on it, and you replace the end-of-line receptacle with a GFCI. Then you add a new cable feeding a new receptacle downstream of it on the load side of the GFCI, and you connect the EGC in the new cable to the GFCI and to the downstream (protected) receptacle.

    Now, suppose you have 3-prong pieces of equipment plugged into each of the two new receptacles. Each piece of equipment has a metallic case bonded to the EGC. Say one piece of equipment has an internal hot to case fault. Nothing happens, as there is no fault path, so no current flows. But the EGC of the new cable connects the case of the faulty appliance with the case of the other appliance. So now both appliance cases are "hot", and touching either one while grounded will cause a shock. [Admittedly a low duration one if the GFCI is working, but a shock none the less.]

    That is why 406.4(D)(2) prohibits connecting the EGC when using its allowance. Now the situation of a circuit with a "lousy" ground is different as even a lousy ground would allow enough current to flow to trip the GFCI upon the initial hot to case fault. But 406.4(D)(2) doesn't contemplate "lousy" grounds, so it has no provision for connecting the EGC in that case.

    I'll post the whole section next for your perusal.

    Cheers, Wayne
     
    Last edited: Sep 15, 2020
  8. wwhitney

    wwhitney Well-Known Member

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    BTW, hopefully the OP has modern enough AC cable that it has a bonding strip and this whole discussion is moot. It would easy enough to kill power to the circuit and disconnect the cable from the box to check.

    Below is 2017 NEC 406.4(D) in part:

    Cheers, Wayne

    406.4(D) Replacements. Replacement of receptacles shall comply with 406.4(D)(1) through (D)(6), as applicable. Arc-fault circuit-interrupter type and ground-fault circuit-interrupter type receptacles shall be installed in a readily accessible location.

    (1) Grounding-Type Receptacles. [ . . . ]
    (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 or their cover plates 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. Where grounding-type receptacles are supplied through the ground fault circuit interrupter, grounding-type receptacles or their cover plates shall be marked “GFCI Protected” and “No Equipment Ground,” visible after installation. An equipment grounding conductor shall not be connected between the grounding type receptacles.
    Informational Note No. 1: Some equipment or appliance manufacturers require that the branch circuit to the equipment or appliance includes an equipment grounding conductor.
    Informational Note No. 2: See 250.114 for a list of a cord-and-plug-connected equipment or appliances that require an equipment grounding conductor.
    (3) Ground-Fault Circuit Interrupters. [. . .]
    (4) Arc-Fault Circuit-Interrupter Protection. [. . .]
    (5) Tamper-Resistant Receptacles. [. . .]
    (6) Weather-Resistant Receptacles. [. . .]
     
  9. WorthFlorida

    WorthFlorida The wife is still training me.

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    Retired
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    When three prong outlets started the metal casings where used as the ground. Obviously the metal corrodes and you could lose the ground and many years ago a third ground wire became code. The armored cable you have looks like it is 3/4" and it probably was empty and wires ran in it later. You can still buy it and it is named flexible conduit in aluminum or steel. Since electricians ran new wire to this outside outlet, there must be a juncture box close buy on the inside or in the crawlspace or basement. I would find that junctor box ( or breaker panel) and run new 14/2 with ground (or 12/2) from the junctor to the new location. then abandon this box but disconnecting the wires both ends.

    https://www.homedepot.com/p/AFC-Cab...-Flexible-Steel-Conduit-5503-22-AFC/205071931
     
  10. MattinLa

    MattinLa New Member

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    Los Angeles
    Thanks all.

    I checked all the outlets and fixtures on this circuit and all are properly grounded, I'll check for a bonding strip this afternoon (fingers crossed).

    I'll also go to the attic as well to follow the path and see if there's a junction box upstream.

    Seems like I might be needing to get a pro in here to take care of this, was hoping it would be a simple thing moving the outlet, but if its more complicated I don't like messing with electrical.
     
  11. Reach4

    Reach4 Well-Known Member

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    Location:
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    Plausible scenario, and you are probably right.
     
  12. wwhitney

    wwhitney Well-Known Member

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    Location:
    Berkeley, CA
    Could be FMC, but my eyes at least can't tell the difference between FMC, AC, and MC from a picture.

    If it's FMC, and less than 6' of it is used in the circuit, and the circuit is protected by at most a 20A breaker, then it's an acceptable EGC (NEC 250.118(5)). Likewise, if it's AC cable that isn't really old and therefore has a bonding strip, it's an acceptable EGC. Or if it's very modern MC/AP cable (presumably not), then it's an acceptable EGC.

    Cheers, Wayne
     
  13. MattinLa

    MattinLa New Member

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    Los Angeles
    I did some more investigating this morning. There is no bonding strip (home was built in the 50's, if that helps). I followed the whole line, it is all encased in 3/4" MC cable, with metal junction boxes along the way.

    Am I able to remove this outlet and metal box and replace it with new MC starting from the junction box upstream from it (runs to the vanity light just above). Then run the new MC wire and box to my desired location?

    Thanks again for the replies.

    -Matt
     

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  14. wwhitney

    wwhitney Well-Known Member

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    Location:
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    FWIW, none of that is MC cable. MC cable has a green grounding conductor inside of it. It's either AC cable or FMC with individual conductors pulled into it.

    In the first picture, the top wiring method is definitely FMC, which someone has pulled NM inside of ! (And what did they do with the bare grounding conductor?)! The others look older, and I don't know enough to distinguish between AC and FMC.

    Certainly if you remove the box shown in the OP and remove the cable connecting it to the next upstream box, that's fine. As to running a new cable to a new location from that box, that's also fine, except that any new circuit should be a grounded circuit (have an EGC). So if you don't have a valid EGC in that upstream junction box, you're supposed to go farther back to a circuit had does have an EGC, back to the panel if necessary.

    Cheers, Wayne
     
  15. MattinLa

    MattinLa New Member

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    Got it thanks Wayne! Seems like a call to an electrician is in store. Putting in the new cable I can handle. Running a ground all the way back to the panel feels out of my league.

    Best,
    Matt
     
  16. Stuff

    Stuff Well-Known Member

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    Location:
    Pennsylvania
    Must be FMC as true AC that old would not have that bright white wire. It would be faded white paint over black cloth over rubber with a tinned copper wire. Then wires get wrapped in brown paper.

    Rather than replace, a patient person might be able run a green ground from outlet to outlet back to the main panel through the FMC.
     
  17. MattinLa

    MattinLa New Member

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    Thanks originally there was cloth-wrapped wire inside, we had the house re-wired years back. Seems odd to me that they didn't pull ground wires too?!? Oh well. Maybe I can try pulling a ground through... and if it proves too much hire in a pro. Sounds kinda daunting to me though. And I'm not so sure I want to be messing with the panel. I have a feeling once my wife hears the options, she's going to say to leave the original outlet where it is and call it day.
     
  18. wwhitney

    wwhitney Well-Known Member

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    So, if there was cloth wrapped wire inside, it probably was AC cable (I think). Reusing the metal sheath and pulling new conductors in isn't actually an approved wiring method. Seems like it would be very tight, as well, which is why they didn't pull a grounding conductor.

    Cheers, Wayne
     
  19. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

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    New England
    My mother's house was wired like yours. One day, out of curiosity, I checked the continuity between the neutral and the armor, and it was very poor. Over the years, with the plaster, humidity, and age, things rusted. It might have been good when first installed, but after 65-years...no longer! I wasn't up for rewiring the whole house, so searched out and located the first receptacle in each run then replaced that with a GFCI and fed-through the rest on that chain with new receptacles and the required label. Over that amount of years, the spring tension on most of them was terrible, so that was the main reason to consider updating things. Having GFCI protection could have been done at the panel, but the panel was old, and finding GFCI breakers for it wasn't going to happen.

    So, this made things safer, but not as good as actually having a ground. Almost, though, and better than a grounded circuit without GFCI protection.
     
  20. WorthFlorida

    WorthFlorida The wife is still training me.

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    Good move, if you're not comfortable with electricity, don't do it.
     
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