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  1. #11
    Join Date
    Jan 2008
    Posts
    1,905

    Default Re: Should I replace all BX cable?

    Crumbly insulation at any point means replace the wire. You can't see most of it and if what you can see is degraded there's a good chance it can be degraded too.

    BX shield can form a ground, but is no longer permitted to be used that way because at best it is not a good ground connection. If the runs and bends allow it, you might be able to pull new conductors (of the correct type) through the shield instead of opening the walls; just include a ground wire too and you should be good to go. Normal wire-pulling techniques are not easy doing this in such a small diameter space and you need to ensure that the insulation isn't being damaged by sharp edges on the way in- have a helper watch and feed the new wires as you pull and install grommets where needed.

    Phil

  2. #12
    Join Date
    Jan 2014
    Location
    El Paso, TX
    Posts
    34

    Default Re: Should I replace all BX cable?

    I'm jumping in a little late but am concerned about one of your posts.

    Just because your tester says you have a ground doesn't mean you have a good ground. If you don't have the little bonding wire, a tiny silver colored wire with no insulation, running alongside your two wires then you have a potentially dangerous situation. Given the apparent age of your wire it is a good bet you don't have a bonding strip meaning you don't have a safe ground.

    Should you have a short to your metal jacket you could end up with a fire.

    What happens is as the short travels back to the panel it will arc from spiral to spiral throwing out red hot metal along the way. I have seen this happen and it is major fireworks. Further without a good ground you may not throw the breaker meaning the fireworks continue indefinitely. I have seen this happen.

    The little bonding strip gives the short a safe path from spiral to spiral avoiding the fireworks.

    AC is not the greatest cable around although it works okay. Some locales don't allow it insisting only MC be used.

    I recommend you replace all the BX.

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