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  1. #14
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    Quote Originally Posted by jtrammel View Post
    On furnaces with flame rectifiers its imperative to have a proper ground to the furnace. I've had some that work fine for years with 2 wire and no ground then all of a sudden it starts locking out until a ground is run to the furnace. That's probably why the lead tech has made a habit of it.

    When a rectification circuit changes behavior, a ground may correct the issue, but the problem is IN the unit.

    Just an fyi.
    [Avatar photo from a Florida training accident. Everyone walked away.]
    2 Tim 3:16-17

    RSES CMS, HVAC Electrical Specialist

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  2. #15
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    Quote Originally Posted by timebuilder View Post
    Only certain types of that kind of cable are eligible for use as a grounding conductor.

    Generally, what is shown in that pic is not suitable.

    Glad I asked.
    Im glad you asked too. If this is not acceptable a water pipe is?

  3. #16
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    Let me see if I can put this in proper perspective.

    The reason that we bond piping in a house is in the event it becomes energized, it will already be at system ground potential, and it will assist in opening the overcurrent device.

    It would be a departure from approved methods to intentionally USE a water pipe as an equipment grounding conductor as part of a planned installation of a piece of utilization equipment, such as an air handler.

    First, I would replace that cable with enough MC with ground to reach a box that contains a genuine EGC, and connect to that conductor for the ground.

    If that is not possible, I would consider extending a known good ECG from the closest location, securing that conductor to the outside of the armor.

    In the event that an inspector wants a water pipe connection, I would make certain that listed clamps are used to secure the EGC to the pipe, and that the pipe is correctly bonded near the service, as well.

    I would also work very hard to convince all involved about option one being the hands-down best choice.
    [Avatar photo from a Florida training accident. Everyone walked away.]
    2 Tim 3:16-17

    RSES CMS, HVAC Electrical Specialist

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  4. #17
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    Ok, I was aware replacing with 2wire and ground was the best option. Eventually im gonna buy a copy of the NEC im sure you would be of great help trying to decipher it. Thank you.

  5. #18
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    Quote Originally Posted by Core_d View Post
    Ok, I was aware replacing with 2wire and ground was the best option. Eventually im gonna buy a copy of the NEC im sure you would be of great help trying to decipher it. Thank you.
    Because we all service and install equipment that runs on electricity, each of us should have a copy.
    [Avatar photo from a Florida training accident. Everyone walked away.]
    2 Tim 3:16-17

    RSES CMS, HVAC Electrical Specialist

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  6. #19
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    Quote Originally Posted by timebuilder View Post
    Only certain types of that kind of cable are eligible for use as a grounding conductor.

    Generally, what is shown in that pic is not suitable.

    Glad I asked.
    Often, what is shown in the picture is old-school BX cable, the outer armor of which is definitely NOT acceptable for use as an EGC.

    Some modern MC and AC cables are acceptable, and they are mentioned in 250.118 (8) and (10).
    [Avatar photo from a Florida training accident. Everyone walked away.]
    2 Tim 3:16-17

    RSES CMS, HVAC Electrical Specialist

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  7. #20
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    Thats good to know

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