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An engineer's shop panel, anbody see errors?

Post in 'DIY and General non-hearth advice' started by Highbeam, Jul 18, 2013.

  1. ScotO

    ScotO Guest

    For the stuff I bury from the barn to the garage, I'll probably be using the heavy 1/2" pex line.....that is some tough stuff, not to mention I have several rolls of it left over from when I re-plumbed the house........

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  2. jharkin

    jharkin Minister of Fire

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    Ive read it reccomended not to use PVC for air lines because if it gets very cold and ruptures, it can explode into shrapnel. The systems like rapid air are made from a heavy nylon like material that won't shatter if it where to burst.
  3. Locust Post

    Locust Post Minister of Fire

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    Just for the record I did not say I agree or recommend it just making the statement.
  4. ScotO

    ScotO Guest

    I like the pex for the air application.....cheap fittings, the crimp-on collars are foolproof, and that tubing is some tough stuff.....
  5. jharkin

    jharkin Minister of Fire

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    @ Highbeam and Scotty - whats the pressure rating of the Pex? I wonder if the rapidair stuff is made out of the same material...
  6. bmblank

    bmblank Minister of Fire

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    Pex is generally rated at about 80psi @ 200 degrees f, if i recall. That is as printed on my 1/2" o2 barrier from Menards.
  7. jharkin

    jharkin Minister of Fire

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    Intersting, thanks. I just goggled both.


    I found a reference for Pex at 100PSI @ 180F and 160PSI @ 74F.

    Rapidair is rated for 150PSI, no temp spec. Its made of nylon, not polyethylene. The fittings for the system all look like standard Festo air fittings.


    When I get to plumbing my shop for air I will have to look at and price out both options....
  8. fbelec

    fbelec Minister of Fire

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    well. i studied the code book. i am just use to using #6 for anything 100 amp amp smaller it says in section 250.66 that anything size #2 or smaller be #8 copper or #6 aluminum. i thought about #6 romex and i think it is #8 ground.
  9. Highbeam

    Highbeam Minister of Fire

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    We saved some cash by downsizing that copper ground. That ground wasn't even required prior to the most recent NEC versions. Kinda like those stupid TR outlets!

    My Mr. Pex brand barrier pex that I used for the floor is rated at 100 psi @180 degrees. Remember though, that's water pressure and I suspect that it matters since air is easier on tube as it compresses instead of hammering.

    Another issue is UV exposure. I have heard that the PEX shouldn't be exposed to UV so perhaps the much more expensive rapidaire stuff is better with UV?
  10. Joful

    Joful Minister of Fire

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    Highbeam, based on what I've always seen done here:

    1. Ground and neutral to be kept separate, when bringing ground from main panel to sub panel.

    2. In a detached building with its own ground rod, and no ground supplied from main, ground and neutral are to be bonded at entrance of new ground.

    In summary, ground is to be bonded to neutral only once, at initial service entrance.

    So, based on your description, I would anticipate you want to bond your ground and neutral, in this particular case. Can you confirm that you only brought two hots and neutral from main house, and are supplying new ground at entrance to detached garage?
  11. Highbeam

    Highbeam Minister of Fire

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    No, your item #2 is in violation of code. All subpanels in detached buildings must have 4 wire feeds and isolated neutral/ground busses. You are correct that ground and neutral is to be bonded only at the main panel. In the past, you could do a subpanel with only three wires but that was before my time.

    In my shed subpanel, I have 3-#6 conductors and a ground of smaller gauge. The required 4 wire feed.
    fbelec likes this.
  12. Joful

    Joful Minister of Fire

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    Like I said... "what I've always seen done around here." I guess this was standard procedure / code at one time, but perhaps not the practice today. I've owned two detached garages in the past, both wired professionally and inspected, which were both done this way. The last one was electrified ca.1990. I'll have to open up the panel in my new detached garage, and see how they did that one, ca.1994.
  13. Highbeam

    Highbeam Minister of Fire

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    Yes, it is no longer a legal way to do it. You must have a 4 wire feed now but that change was fairly recent like in the 2000s. I was alive but it was before my time installing panels. It is good to have an electrician friend that opens the book every time I ask a question. He knows the answers but also knows that I want to see it.
  14. Highbeam

    Highbeam Minister of Fire

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    Thanks everyone, I easily passed the insepction with no corrections required.
    Joful and jharkin like this.
  15. fbelec

    fbelec Minister of Fire

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    btw sorry i didn't say so earlier

    nice job

    way neater than some of the guys round here.

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