Long flex metal conduit instead of rigid pipe?

Discussion in 'Electrical Forum discussion & Blog' started by electrotuko, Jun 17, 2008.

  1. electrotuko

    electrotuko New Member

    Messages:
    47
    Location:
    Chicago, IL
    If the pricing is not an issue and I need very quickly to install additional outlet and some light fixture in my basement: Can I ran a flexible metal conduit instead of rigid metal pipe?
    The line length would be more than 40 feet.
  2. Bob NH

    Bob NH In the Trades

    Messages:
    3,317
    Location:
    New Hampshire

    Forty feet of flex conduit isn't legal (NOTE/CORRECTION: The length limit statement is incorrect and was brought to my attention by Mikey. There is no limit on FMC.) but you could use prewired MC (the new version of BX).

    I have run 1" PVC through joists on 16" centers but it is diffucult. You can run 1/2" PVC conduit through studs almost as easily as flex, and it is easier to get the wire through it. Put the PVC out in the sun for a while to make it even easier. Just be sure you run a line to make the holes in the studs line up.
    Last edited: Jun 18, 2008
  3. electrotuko

    electrotuko New Member

    Messages:
    47
    Location:
    Chicago, IL
    Bob, thank you for your advice.
    Can I run a conduit not through the holes in the studs but attach it to the bottom of studs (to the edges by using clamps or so)? Would be easier and no holes drilling.
  4. Bob NH

    Bob NH In the Trades

    Messages:
    3,317
    Location:
    New Hampshire
    You can attach it to the studs and joists. It is permitted for exposed work where not subject to physical damage NEC 352.10(F). Carlon Schedule 40 Rigid Nonmetallic Conduit is listed for exposed or outdoor work; and I expect that other brands are also listed for exposed work.

    1/2" PVC must be supported every 3 ft. That usually means every other joist or stud.
  5. Speedy Petey

    Speedy Petey Licensed Electrical Contractor

    Messages:
    992
    Location:
    NY State, USA
    WHY are you running conduit at all????

    Is it required by code where you are?
  6. electrotuko

    electrotuko New Member

    Messages:
    47
    Location:
    Chicago, IL
    Thanks for advises.
    I am in Illinois, Kane county.
    It is an old house, all new electrical instalation-additions be the previous owner were done using metal conduit. I was assuming that it is required to have conduits. Never thought that it might be not true. Would be nice to know what the code says.
  7. Mikey

    Mikey Aspiring Old Fart, EE, computer & networking geek

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    Location:
    Central Florida
    Why isn't it legal?
  8. Bob NH

    Bob NH In the Trades

    Messages:
    3,317
    Location:
    New Hampshire
    My mistake. I was thinking of the 6 ft limit beyond where it is securely fastened for connection to fixtures or other equipment. There is otherwise no limit for length of FMC.
  9. Billy_Bob

    Billy_Bob In the Trades

    Messages:
    422
    For the most part electrical codes are standard throughout the U.S., but local areas have their own modifications to the National Electrical Code. I don't know why this is, but maybe because some areas are quite cold, others quite hot, some dry, some very wet, some have earthquakes, etc. Maybe regional differences cause certain problems to crop up and they modify the code for this?

    For example I've seen modifications in some areas for flex conduit installation.

    Anyway conduit is a good thing because it protects the wiring. Also even if it was not required, I would run the new wiring the same just for "looks".

    If you are interested in the code for this, go to your local electrical inspector's office and just ask. The offices in my area have certain times of the day where anyone can go and ask questions. Take plenty of pictures of the area where you want to do the work. Then the inspector can better determine what would be required.

    It is no big deal to get a permit in many areas. Plus then you have an expert checking your work to be sure it is ok. A good learning experience!
  10. electrotuko

    electrotuko New Member

    Messages:
    47
    Location:
    Chicago, IL
    Thanks to all of you for consultations. I will use PVC conduit, nice looking and cost effective.
  11. Speedy Petey

    Speedy Petey Licensed Electrical Contractor

    Messages:
    992
    Location:
    NY State, USA
    If you're in Chicagoland I'd check if that's compliant if I were you.
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