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rwiegand

upgrading receptacles with undersize ground

rwiegand
7 years ago

Lots of conflicting info out there. I will ask my inspector, but I'd like to go into that conversation with the best information in hand-- he's very unhappy that his office granted a permit to an unlicensed homeowner, so I need to appear as competent as possible. (Amusingly, he just signed off on my rough-in after finding no problems, grumbling furiously all the while. He seemed angry that I did it all correctly.)

The part of the house I am not rewiring has two prong outlets and the boxes are wired with 14-2 NM cable that has a 16 ga ground. (common apparently between 1950 and 1970). The grounding wire is currently attached to the boxes.

I'd like to install three prong outlets.

May I install a three prong outlet, wiring the ground to the receptacle and including a pigtail to ground the box? Or, must I protect the circuit with GFCI and mark the receptacles as ungrounded? In the latter case may I attach the undersize grounding wire to the receptacle or not?

Opinion on the interweb is all over the place on this, so I'd really appreciate a reference to code (2009 is the relevant version in my jurisdiction). I haven't been able to find a direct answer myself, so I appreciate the help of the pros here.

Thanks!

Comments (16)

  • Ron Natalie
    7 years ago

    My read of the code (and this hasn't changed between 2009 and 2014 to my knowledge) is that you have a grounding conductor (even if it is deficient by modern codes) and hence any device that has a grounding connection MUST be connected to it. Similarly, I see no reason why installation of a grounding type receptacle would require a GFCI here. But again, your local jurisdiction may have other ideas.

  • Bruce in Northern Virginia
    7 years ago

    If the 16 gauge ground wire was legal for a 15 amp circuit when the house was built, it is grandfathered. Upgrading to the new code is only required where you are doing new work (adding additional wire, outlets and circuits. Using a smaller gauge ground wire is not optimal, but it was a legal ground when installed.

    If all you are doing is changing the receptacle "device" (not adding a new box) and running a ground wire over to the metal boxes, most cities would require a permit or inspection.

    Bruce

  • Vith
    7 years ago
    last modified: 7 years ago

    Or just upgrade the outlets later when no one will make a stink about it or notice...

    (Amusingly, he just signed off on my rough-in after finding no problems, grumbling furiously all the while. He seemed angry that I did it all correctly.)

    Pompous A55 ^^

  • Ron Natalie
    7 years ago

    Actually, even extending that circuit is probably OK (it us as far as the NEC goes) but again your local authority may have a difference of opinion.

    I think you mean it wouldn't require a permit or inspection, but I think based on the fact that he is talking about rough ins he's doing more of a project than just upgrading the receptacle devices.


  • rwiegand
    Original Author
    7 years ago

    Given the mash-up of weird stuff I've found inside the boxes I've opened I want to replace all the "devices" in the house that aren't otherwise being completely replaced/rewired. Using the available grounding wire certainly makes sense to me.

  • User
    7 years ago
  • User
    7 years ago

    "even extending that circuit is probably OK"

    It would need the properly sized ground wire to be connected to something other than the 16 gauge wire per 250.130

  • Ron Natalie
    7 years ago

    Nothing in 250.130 implies that this is not acceptable. In fact, since you can connect it to any equipment ground it would seem that the size is unimportant.

  • User
    7 years ago
    last modified: 7 years ago

    250.122 Size of Equipment Grounding Conductors

    (A) General. Copper, aluminum, or copper-clad aluminum equipment grounding conductors of the wire type shall not be smaller than shown in Table 250.122,...

    If the wire is smaller than what is allowed by Table 250.122, it is no longer considered an EGC. It is just a wire that happens to be grounded. If it were truley considered an EGC when it was originally installed, there would be grounding type receptacle on the circuit already, and the original question would never have had to be asked.


  • Ron Natalie
    7 years ago

    I disagree, it was an EGC at the time it was wired. The code is gracious about extending and grounding branch circuits on existing wiring. They will even allow you to use another circuit's ground which is likely worse off than just using the undersized-by-today's-code ground. Again, he'd have to consult the local authority. The NEC doesn't in my opinion prohibit it.

    Things don't "cease" to be wiring just because they code changes.

  • User
    7 years ago
    last modified: 7 years ago

    How could it be an EQUIPMENT grounding conductor when the receptacle didn't even have a grounding slot? New wiring must meet new codes PERIOD. If there is a direct short from hot to ground, the 16 gauge wire will normally melt. That is why it was only allowed for such a brief time in history. It would be FAR BETTER to use an appropriately sized ground from another circuit. In fact, grounding wires from different circuits are bonded together all the time in multiple gang switch boxes, providing multiple paths to ground. Before 2014, nothing smaller than the Grounding Electrode Conductor was allowed for branch extension grounding.

    Newly written codes often have unintended consequences where people try to twist the code, and take it out of context with the rest of the codes. It will be rewritten because of people like you who want to take the easy route at the cost of safety. It is not even allowed to upgrade the wiring on a 20 amp circuit to 10 gauge wire within also increasing the size of the EGC to 10 gauge as well. Because, the 10 gauge wire will facilitate a surge of much higher amperage in the event of a direct short than the 12 gauge wire can effectively handle.

    250.122

    (B) Increased in Size. Where ungrounded conductors are increased in size, equipment grounding conductors, where installed, shall be increased in size proportionately according to the circular mil area of the ungrounded conductors.

    .

    Saying that it is OK to extend from the under sized ground because it was to code once is as absurd and dangerous as saying that it is OK to upgrade a service from 60A to 200A without replacing the Grounding Electrode Conductor with the appropriate size just because it was up to code when the original service was installed.

    You can not add additional wiring without the properly sized EGC going to a ground of equal or larger size either, or all the way back to the panel. Many states have even amended 250.130 to disallow many of the options because it is not possible to readily know if a ground path has been interrupted during future remodels. For example, If you were to extend a circuit, and bond the ground to a GEC that is in the house, then upgrade the service, and just cut off the old undersized GECs when installing the new ones, you would unknowingly end up with an ungrounded extension. The same thing with water pipes when they change parts of it to PEX in the future.

    Ground wires smaller than allowed by 250.122 are not allowed anywhere in the code. 250.130 does NOT give permission to ignore the rest of the code for new or extended circuits. Grandfathering only applies to existing wiring, not extensions. The code does not say that you only need to follow the convenient parts of the code. It does say that new work must FULLY meet ALL parts of the code unless there is an explicit exception.

  • hrajotte
    7 years ago

    ANY size conductor will melt with a direct short if the OCD fails to open fast enough. If there was no OCD, then the transformer fuse would blow. And hopefully you would not have a fire!

  • Ron Natalie
    7 years ago

    You're putting words in my mouth. I didn't say it was ok to use an undersized because it was once in the code. I said that the existing ground was to CODE when it was installed and that the rules for adding grounded receptacles to ungrounded circuits permits you to connect to any existing (legal at the time it was installed) ground. It even permits this when the ground is on a completely different circuit. This shoots your whole "It's got to be in this table" argument in this specific case.

  • User
    7 years ago
    last modified: 7 years ago

    No, YOU are trying to put words into the code.

    Show me in the code where you can use a "(legal at the time it was installed)" ground even though it is undersized on any NEW work. Your argument exists solely on disregarding the code for NEW work. An extension of a circuit is NEW work PERIOD. If you do ANY new work, it has got to comply with new codes. There is NO exception in the code that says you can use an undersized ground for new work. By your argument, I can upgrade a service from 100 amps to 200 amps without replacing the grounding electrode conductor to the proper size because an undersized one already exists. The code most definitely does not say "that the rules for adding grounded receptacles to ungrounded circuits permits you to connect to any existing (legal at the time it was installed) ground". You even seem to feel the need to put "(legal at the time it was installed)" in brackets because you know that it is NOT in the code, and you are trying to add it. Show it to me in the actual code text without adding it yourself.

    "It even permits this when the ground is on a completely different circuit."

    It is not only allowed, but is required if the ground for the new work would not be the required size all the way back to the panel. The code you are trying to misconstrue is meant to make sure there is an adaquate ground by current codes, not make it allowed to use an undersized ground. Suggesting this is irresponsible. Good thing you do not have a license to do this kind of electrical work.

  • wolpeg
    7 years ago

    Fred S wrote on September 18, 2016 at 5:31 p.m.:

    " If there is a direct short from hot to ground, the 16 gauge wire will normally melt."

    Precisely that happened to me in August 2016, while attempting to correct a reversed hot/neutral connection to an outlet when I noticed black and white wires swapped in a junction box. Unbeknownst to me, the weekend warrior DIYer who had done the wiring (my dad), had indiscriminately mixed wire colors in his house and wired about half the outlets with hot and neutral reversed and neutral and ground tied together or swapped.. After making the wiring change, I flipped the breaker for that circuit on at the main panel and the entire panel growled in a way I had never experienced before. After two seconds of this noise, I cut the breaker and walked around the corner to see smoke pouring out of the door of the enclosed patio. About 10 feet of late-1960s Type NM cable had fried. It was 12-2, with a 16 AWG ground. The ground wire actually melted, charring the plastic cable jacket along the entire length, but the breaker never tripped. Considering that the water service was shut off and I didn't have a cell phone with me at the time, I consider myself very, very lucky not to have burned the place down! It was also fortunate that the incident happened in a run of cable that was in an exposed location, not buried in a wall. The upshot of it its that I am now going through the entire wiring system with a fine-tooth comb, weeding out code violations one by one. While doing so, I temporarily removed the 100 A cartridge fuses from the main fuse box and jury-rigged a couple of 15 A circuit breakers as substitutes. I figure if I accidentally create another short circuit, even the 16 AWG ground wire will survive a 15 A overload and cause the breakers to trip.