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  1. #1
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    Default Upgrading electrical outlets

    I would like information regarding converting a 2 prong out to a 3 prong grounded outlet. All websites that I visit describes a receptacle that has existing ground wires in it. My house was built in 1959 and does not have ground wires to the outlets. Will it meet code if I attach a ground wire to the back of the metal junction box and then to the receptacle? Thanks so much for your input.

  2. #2
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    Default Re: Upgrading electrical outlets

    Not likely, unless you have conduit to the boxes the box is not grounded so attaching a wire to it would do no more good than hanging it out the window. You will need to run a ground wire from the main panel, which must be properly grounded and your jurisdiction allows this or you will need to replace the wiring with 2 cond plus ground.
    Jack
    Be sure you live your life, because you are a long time dead.-Scottish Proverb

  3. #3
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    Default Re: Upgrading electrical outlets

    Quote Originally Posted by JLMCDANIEL View Post
    Not likely, unless you have conduit to the boxes the box is not grounded so attaching a wire to it would do no more good than hanging it out the window. You will need to run a ground wire from the main panel, which must be properly grounded and your jurisdiction allows this or you will need to replace the wiring with 2 cond plus ground.
    Jack
    Jack,
    There is conduit to the boxes. Will that allow for attaching a ground wire to the back of the junction box? When I test each outlet, it shows no open ground. If this is not acceptable, does this mean you have to re-wire your house to change from 3 prong to 3 prong outlets? My two prong outlets are old and need replaced. Thanks for your input
    Last edited by Buckie 777; 09-05-2008 at 02:24 PM.

  4. #4
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    May 2008
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    New Jersey
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    Default Re: Upgrading electrical outlets

    Dont just assume the conduit is effectively bonded because your plug tester or digital meter says no open ground. the NEC is a minimum standard and although it may permit this under the right situation (less than 20 ohms between current carrying parts etc..)it wouldn't be good practice or a good idea to rely on conduit 50 years old for an equipment ground. pull a peice of thhn its not that hard. a fault current can heat that conduit up like an element in an oven if the resistance to ground is much greater then 20-30 ohms. if you insist on taking this short cut put a megger on it first.

  5. #5
    Join Date
    Jun 2007
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    Shamokin, Pa.
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    Default Re: Upgrading electrical outlets

    Quote Originally Posted by lmills148 View Post
    Dont just assume the conduit is effectively bonded because your plug tester or digital meter says no open ground. the NEC is a minimum standard and although it may permit this under the right situation (less than 20 ohms between current carrying parts etc..)it wouldn't be good practice or a good idea to rely on conduit 50 years old for an equipment ground. pull a peice of thhn its not that hard. a fault current can heat that conduit up like an element in an oven if the resistance to ground is much greater then 20-30 ohms. if you insist on taking this short cut put a megger on it first.
    I might add that by using one of the original Thhns as a pulling device. {If possible**
    Just make sure you replace that original wire while pulling the green ground wire.

  6. #6
    Join Date
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    Denver, CO
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    666

    Default Re: Upgrading electrical outlets

    Quote Originally Posted by lmills148 View Post
    Dont just assume the conduit is effectively bonded because your plug tester or digital meter says no open ground. the NEC is a minimum standard and although it may permit this under the right situation (less than 20 ohms between current carrying parts etc..)it wouldn't be good practice or a good idea to rely on conduit 50 years old for an equipment ground. pull a peice of thhn its not that hard. a fault current can heat that conduit up like an element in an oven if the resistance to ground is much greater then 20-30 ohms. if you insist on taking this short cut put a megger on it first.
    Fairly good post................But I am able to read between the lines. Most home owners have no idea about what you are talking about. And, no knowledge or way to test, or the equipment and knowledege to use it.

    So, why not offer some friendly alternatives?

    If your wiring is in conduit it would be cheap and easy to replace the wiring with all new conductors including a green grounding conductor to all devices.

    Add:

    I know the NEC allows conduit as a sole means for a grounding method. I've personally never used it and have always used a grounding (wire) conductor included with the circuit wiring. The old wiring is probably TW. I'd suggest you replace all of it with THHN, THHW wiring which has a higher temp rating while you are at it.
    Last edited by kentvw; 09-30-2008 at 07:56 PM.

  7. #7
    Join Date
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    Default Re: Upgrading electrical outlets

    Quote Originally Posted by kentvw View Post
    Fairly good post................But I am able to read between the lines. Most home owners have no idea about what you are talking about. And, no knowledge or way to test, or the equipment and knowledege to use it.

    So, why not offer some friendly alternatives?

    If your wiring is in conduit it would be cheap and easy to replace the wiring with all new conductors including a green grounding conductor to all devices.

    Add:

    I know the NEC allows conduit as a sole means for a grounding method. I've personally never used it and have always used a grounding (wire) conductor included with the circuit wiring. The old wiring is probably TW. I'd suggest you replace all of it with THHN, THHW wiring which has a higher temp rating while you are at it.
    Solid or stranded?

  8. #8
    Join Date
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    Denver, CO
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    Default Re: Upgrading electrical outlets

    Quote Originally Posted by Ernie_Fergler View Post
    Solid or stranded?
    That ain't too funny right now. I have an electrician in Steamboat Springs as I type this replacing solid wire that was specified to be stranded...... On my dime.............

  9. #9
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    The deep South
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    Default Re: Upgrading electrical outlets

    Quote Originally Posted by lmills148 View Post
    a fault current can heat that conduit up like an element in an oven if the resistance to ground is much greater then 20-30 ohms.
    Check your Ohm's law .

  10. #10
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    Denver, CO
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    Default Re: Upgrading electrical outlets

    Quote Originally Posted by djohns View Post
    Check your Ohm's law .
    Throw a calc out there Dan?

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