outdoor to indoor wiring question.

Discussion in 'Electrical Forum discussion & Blog' started by trackerxx, Apr 17, 2012.

  1. trackerxx

    trackerxx New Member

    Messages:
    7
    I have mounted an outdoor box on an exterior wall and have drilled a hole for a conduit nipple to go through the wall. Can I put Romex through that hole and continue the Romex to the nearest electrical box inside? The wire would be coming stright through the nipple and then immediately by stapled to the nearest studs on the way to the electrical source. Thanks.
  2. hj

    hj Moderator & Master Plumber Staff Member

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    27,250
    Location:
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    The nipple will create a "sharp edge" and the Romex® will not be anchored so it could rub against the raw edge. Use a shorter nipple, then a threaded coupling, and a wire clamp/connector into it. Slide the wire through it and tighten the clamp screws.
  3. Homeownerinburb

    Homeownerinburb New Member

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    525
    Location:
    Los Angeles, CA USA
    HJ is right, but:

    There are two considerations when wire enters a box, generally speaking.

    Abrasion must be avoided. On MC there are little red plastic anti-short bushings. For MC (the stuff you are asking about) there are rated plastic and metal devices that will fit the box and protect the sheathing from abrasion. There must be a dozen different concepts on the market.

    The other issue when any wire or cable comes into a box is that it cannot be pulled back out. For MC the various devices that prevent abrasion also clamp the cable.

    Some of the plastic boxes on the market have no provision to hold the wire from being pulled out, and when used it is expected that the wire be stapled to the framing within 8".

    There are anti-short bushings (collars) that screw over the threads of rigid conduit and present the wires or cable with a much smoother surface to work against.

    All that said, I could imagine replacing the metal conduit that you have with some plastic, and stapling the wire down if you can get at it. Or use a plastic nipple for the second box (the source) that has a good grab on the wire.

    Make sure that you have enough room in the source box,

    Remember: the sheathing must be visible in the box. 1/4 to 1/2 inch is expected.
  4. cacher_chick

    cacher_chick Test, Don't Guess!

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    Location:
    Land of Cheese
    If the nipple is EMT conduit, there is a standard EMT to NM (Romex®) fitting which clamps the NM cable and circumvents the need to use bushings. They are not uncommon, as I get them from the local big-box store.
  5. jwelectric

    jwelectric Electrical Contractor/Instructor

    Messages:
    2,565
    Location:
    North Carolina
    First the original poster is talking about Non-Metallic cable not Metal-Clad cable

    Second there is not requirement to use the anti-short bushing for MC. They are required for Armored Cable or AC cable
    See 320.40 and 330.40
  6. Speedy Petey

    Speedy Petey Licensed Electrical Contractor

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    Location:
    NY State, USA
    WHY the nipple at all?? Just bring the NM into the back of the box. Make sure to seal around the box really well.
  7. Homeownerinburb

    Homeownerinburb New Member

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    Location:
    Los Angeles, CA USA
    No "requirement", but personally, I would not skip them. And the fact that there is always a bag of bushings with the stuff when I buy it suggests to me that I am not alone.

    I brought up the MC in order that the OP would understand that each system has its requirements; I could have been more verbose, but my post was pretty long as it stood.
  8. Homeownerinburb

    Homeownerinburb New Member

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    Location:
    Los Angeles, CA USA
    Broadly speaking, there needs to be SOME sort of chafe protection and strain relief, to be legitimate. I assume you mean to use a connector of some sort. The OP might not understand that if you are not explicit.

    If the box is some sort of cast Bell box with threaded holes, a chase nipple could be screwed in and that would resolve the chafe requirement. A staple to framing within 8" would give you strain relief, I suppose. This would permit a pretty discrete hole in the wall.

    Are we talking about what is safe, or what is perfectly to code? I am sure there are inspectors who would OK the above, and others who would flag it.

    Heck, if the hole in the wall is big enough for a metal connector with a screwed down strap to grab the NM, then all is good, your point to seal the hole in the wall is the necessary cherry on the sundae.
  9. Speedy Petey

    Speedy Petey Licensed Electrical Contractor

    Messages:
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    Location:
    NY State, USA
    When I say "just bring the NM into the back of the box" I mean properly, with an NM connector.
  10. Homeownerinburb

    Homeownerinburb New Member

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    525
    Location:
    Los Angeles, CA USA
    And I assumed as much.
  11. jwelectric

    jwelectric Electrical Contractor/Instructor

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    Location:
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    And those outlined in red above would be wrong and wouldn't have ground to stand on
  12. Homeownerinburb

    Homeownerinburb New Member

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    Location:
    Los Angeles, CA USA
    Yes. And some days it is just easier to give the damned inspector what he wants and get on with the job. As long as it is not going to cost me real money and time, and the job is going to be just as safe, I have been known to swallow it. You, jw, are qualified to teach people stuff. I have yet to meet an inspector who was ready to accept that I was going to teach him or her anything.

    Actually, I did have a pretty good back and forth with a woman who worked for Los Angeles. We agreed on a solution to a problem that cut the distance I was running a service conduit for a 90 amp circuit from about 250' to about 100'. But I would not say that I taught her anything.
  13. jwelectric

    jwelectric Electrical Contractor/Instructor

    Messages:
    2,565
    Location:
    North Carolina
    1. I have been teaching licensing prep and inspectors for more than 12 years now. In each class I tell the students that when the contractor and inspector disagee that the learning process begains for one or the other if not both.

    With inspectors they take an oath to uphold the codes as written and are not allowed to inject their opinions for any reason.

    I also explain that the remark that it is easier to just agree with the inspector is a good way to land oneself in court. As a licensed contractor I am bound by law to make a compliant installation weather the inspector agrees with me or not.

    The use of antishort bushings on MC cable is not required therefore I do not use them. Using them can impede the heat of the conductors as the MC already comes with a liner in the jacket of the sheathing.
    Should someone tell me that I have to use them I promise they will be standing in front of the board that issued them their certification.

    My profession is not up to give away to please an inspector when that inspector is wrong. My profession mandates that I address an inspector that is wrong and not to give in to his/her wishes. I address the inspector in a professional manner and do not ever give them something they want just because they want it.

    I demand that any inspector show me in writing just what they say I have done wrong and if they can't then I am not wrong. This is a two way street that humans walk and as humans we are all subject to mistakes, therefore when two disagree it is part of a learning process.
    Last edited: Apr 19, 2012
  14. Homeownerinburb

    Homeownerinburb New Member

    Messages:
    525
    Location:
    Los Angeles, CA USA
    JW,

    You're persuasive. I'll keep that in mind.
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