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  1. #1
    Join Date
    Jul 2002
    Location
    Centerville, Iowa
    Posts
    384
    Is overwiring allowed by the NEC? For example using 10awg wire for a 20 amp circuit instead of 12awg, 8awg for 30 amps, etc.

  2. #2
    Why wouldn't it be?

  3. #3
    Join Date
    Mar 2003
    Location
    Cincinnati
    Posts
    7,977
    What you read in the NEC is minumum. So if I'm reading your post properly then yes you can use bigger gauge wire than the NEC states.

    Just make sure you run it the way your inspector wants it cause you don't want to do it twice.

  4. #4
    Join Date
    Dec 2003
    Location
    Location!, Location!
    Posts
    929
    "overwiring" like you mention is actually "allowing sufficient conductor area for minimal voltage drop" and is required, like the #10 on those 20 A circuits, when distance or load(large motor-starting) requires. I have installed Vac-Pak machines that required #6 for a 30 amp rla.

  5. #5
    Join Date
    Dec 2003
    Posts
    1,739
    under-wiring is allowed also, on motors. You couldn't Over-wire if the terminal cannot handle the size of the wire that you install. They make pressure connectors, or other means for downsizing the conductor to fit into a terminal. Haircuts are not allowed.
    there but for the grace of god, go all of us

  6. #6
    Join Date
    Jul 2002
    Location
    Centerville, Iowa
    Posts
    384
    Thank you all for your replies. I just didn't know if it was allowed for short runs but since it is I will plan accordingly. I only ask because I lived in a mobile home that only had 2 15 amp 14AWG circuits for receptacles, lighting, and the smoke detectors running the entire length of the house (1 on each side) and any time anything such as the refrigerator kicked on it dimmed the lights severely. So I am assuming it would also be OK to have an electrician wire an entire house with 20 amp branch circuits and #10 in rigid conduit to the boxes then 12AWG 6" pigtails to the actual receptacles (so the wire fits under the screws properly).

  7. #7
    Join Date
    Dec 2003
    Posts
    1,739
    if he is wiring a house in rigid, he must be a glutton for punishment.
    there but for the grace of god, go all of us

  8. #8
    Join Date
    May 2004
    Location
    Rapid City, SD
    Posts
    7,415
    Originally posted by caosesvida
    if he is wiring a house in rigid, he must be a glutton for punishment.
    True, but it'd be a way cool house wouldn't it! When I remodel I plan on doing a couple things rigid so I can "finish later" lol. But a whole house... wow.... wouldn't want to see the bill for that one.

  9. #9
    Join Date
    Mar 2003
    Location
    Cincinnati
    Posts
    7,977
    I ran rigid underground for my pool. Have you ever threaded rigid?? Maybe it was just my pipe threader but it kinda chipped up the threads on the pipe. Still worked but the threads looked crappy.

  10. #10
    Join Date
    May 2001
    Location
    Bennington, Vermont U.S.A.
    Posts
    13,864
    What's wrong with plactic conduit for underground? We use pvc conduit around here all the time and we have rocks.

  11. #11
    Join Date
    Jul 2000
    Location
    Dallas,Texas
    Posts
    4,975
    Did you use NPT threader dies?
    Rigid conduit requires NPSM. No taper.

  12. #12
    Join Date
    Mar 2003
    Location
    Cincinnati
    Posts
    7,977
    Originally posted by wolfdog
    Did you use NPT threader dies?
    Rigid conduit requires NPSM. No taper.
    That's what it was.

    I didn't use pvc or emt cause you had to dig the trench twice as deep and I was the only one digging and it was 90Ί+ out there.

  13. #13
    Join Date
    Jun 2003
    Location
    Florida
    Posts
    9,548
    Originally posted by mattm
    Originally posted by wolfdog
    Did you use NPT threader dies?
    Rigid conduit requires NPSM. No taper.
    That's what it was.

    I didn't use pvc or emt cause you had to dig the trench twice as deep and I was the only one digging and it was 90Ί+ out there.
    Don't blame you there, but trenchers rent inexpensive. Is that a local code on trench depth depending on what type of conduit?
    If everything was always done "by the book"....the book would never change.

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