Machine grounding
Close
Login to Your Account
Likes Likes:  0
Results 1 to 7 of 7
  1. #1
    Join Date
    Mar 2019
    Country
    UNITED STATES
    State/Province
    Texas
    Posts
    175
    Post Thanks / Like
    Likes (Given)
    3
    Likes (Received)
    6

    Default Machine grounding

    Iím trying to fill out the forms to get a tech out to set up the machine and Iím just seeing some requirements that I donít meet but can be fixed if necessary.

    Haas says the ground needs to be the same size as the incoming wires. Right as it sits I have three #3 for input and the ground wire is #6.
    Is that not good?

    If not can someone explain why the ground and line need to be the same size?

    And laymanís term what do you consider a dedicated ground?

    I have 2 hots and a neutral to my sub panel at shop and then from there to phase perfect to disconnect to machine itís grounded. So Iím grounded back to neutral of main box and shop building. That sounds good to me but Iím no electrician and everyone Iíve talked to are not familiar with phase perfect or cnc machines and they are not comfortable working on it.
    Does any of that sound wrong?

  2. #2
    Join Date
    Sep 2005
    Location
    Northern California
    Posts
    1,000
    Post Thanks / Like
    Likes (Given)
    4
    Likes (Received)
    144

    Default

    I normally pull all my wires in metallic conduit with a bare ground wire to the local disconnect at the machine that home runs back to the main service disconnect. The NEC will tell you what size ground is code for a particular ampacity panel.

    The trunking to the machine gets a second ground wire. Now having said that CNC machines typically want a low impedance ground not for safety but for noise. IF the HAAS tech wants #3 you're likely going to have to pull in a #3 for them to warranty their work.

  3. #3
    Join Date
    Mar 2019
    Country
    UNITED STATES
    State/Province
    Texas
    Posts
    175
    Post Thanks / Like
    Likes (Given)
    3
    Likes (Received)
    6

    Default

    All my wires are pulled through emt but my grounds are not bare.
    I think the #6 ground is the only thing holding me back so I guess it’s better to be safe than sorry and I will pull a 3 through from the machine back to PP.

  4. #4
    Join Date
    Nov 2008
    Location
    Madera county california usa
    Posts
    2,646
    Post Thanks / Like
    Likes (Given)
    21
    Likes (Received)
    683

    Default

    Not an electrician by trade but...

    NEC requires safety ground to be same size as supply lines to insure the current carrying capability of the safety ground is same as supply so it can handle the fault current to trip the breaker.

    However, at some gauge of current feeders the safety ground may be reduced.

    Best to seek guidance of your local building inspector.

    Sent from my SAMSUNG-SM-G930A using Tapatalk

  5. #5
    Join Date
    Jan 2007
    Location
    Flushing/Flint, Michigan
    Posts
    9,690
    Post Thanks / Like
    Likes (Given)
    534
    Likes (Received)
    8021

    Default

    Neutral is not ground. Confusing for sure as it seems bonded to the same
    What you see in size is how to not end up in lawsuit.
    Bob

  6. #6
    Join Date
    Jul 2007
    Location
    Missoula Mt
    Posts
    1,041
    Post Thanks / Like
    Likes (Given)
    45
    Likes (Received)
    448

    Default

    (Not an electrician by trade but...) I am... The NEC does NOT require the ground wire to be the same SIZE as the load conductors. The NEC does have requirements for ground size bases on amps of feeder, but that only there to trip the breaker and shut things down with out melting the ground wire....Phil

  7. #7
    Join Date
    Mar 2019
    Country
    UNITED STATES
    State/Province
    Texas
    Posts
    175
    Post Thanks / Like
    Likes (Given)
    3
    Likes (Received)
    6

    Default

    Yeah the same size ground had me wondering why but no problems bc the haas guy opened the back panel took his readings and set it up no problem. Even said for not being an electrician it looked good. He said he’s seen where certified electricians didn’t do nearly as neat a job. I guess when you are doing the work for yourself or you just care what your work looks like bc that’s how people judge you, you do the best job you can. Not bragging at all but was extremely relieved to hear that and I think I even patted myself on the back lol. Just joking


Tags for this Thread

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •