Plasma cutter question about grounding

Discussion in 'Garages, Workshops & Tools' started by Aceshigh, Aug 4, 2011.

  1. Aceshigh

    Aceshigh Veteran Member Lifetime Gold Member

    26,757
    1
    Apr 9, 2001
    Boondocks
    Hey guys,

    Anyone here that's savvy with Plasma cutter work, please advise.
    I just picked up the Harbor Freight 95136 plasma cutter for some simple
    sheet metal cutting (trans tunnel) and minor other work on my car.

    What I am not sure about is on page #9 lower left side of the manual
    it says to ground the Plasma Cutter itself to a working table or some
    electrode. http://images.harborfreight.com/manuals/95000-95999/95136.pdf

    Is this a 100% of the time thing I need or is it only when I can't make use of
    the grounding clamp to clamp to the work piece ???

    Also, I read some guys had issues with getting a ground on a car, probably
    due to the tires insulating it too much ....I dunno. So how would I go about
    grounding this thing to the earth properly ?? Wire the rear of the chassis to
    a big steel rod and shove it into the ground ??
     
  2. Kamikaze

    Kamikaze Veteran Member Lifetime Gold Member

    Ace

    Not sure about the HF brand.
    My Hypertherm just has a single work clamp to attach to the table or piece you are cutting. I also have a magnetic clamp post I will use on a body shell when trying to get a good ground. Almost always, I will grind even bare metal for a clean ground attachment and not have a problem.

    Never had to ground the actual machine to earth other than the power supply ground.
     
  3. Aceshigh

    Aceshigh Veteran Member Lifetime Gold Member

    26,757
    1
    Apr 9, 2001
    Boondocks
    IT has the working clamp as well for ground.

    This is just something I never saw before, and I don't want to fry it on my first use.
    [​IMG]

    It has a screw on the rear of the plasma cutter chassis it's telling me to put a
    14 GA wire to for a ground. I just couldn't figure out what it need that for. :confused:

    I thought the FRONT ground clamp which clamps to the metal work piece
    helped complete the circuit.....hence my confusion.
     
  4. Kamikaze

    Kamikaze Veteran Member Lifetime Gold Member

    Does the unit have a terminal or lug to attach a grind cable to?
     
  5. Aceshigh

    Aceshigh Veteran Member Lifetime Gold Member

    26,757
    1
    Apr 9, 2001
    Boondocks
    Look at page 9. See if that's what you're asking about.
    Bottom of the page , left side.
     
  6. K5JMP

    K5JMP Veteran Member Lifetime Gold Member

    very poorly written manual..lol:confused:

    black and white are "hot" and the green wire is the "return"... not the ground.

    screw on the back of the machine is to ground the machine... the arrow is a schematic symbol for "earth ground"... which is exactly what it sounds like...
    earth ground generally goes to a ground rod, copper water pipe etc.. or the actual ground wire (usually the thinner bare wire) in romex.. which ultimately ties to earth ground thru your house wiring.

    the "working ground" with the clip goes to the piece of metal you are working on..
     
  7. Aceshigh

    Aceshigh Veteran Member Lifetime Gold Member

    26,757
    1
    Apr 9, 2001
    Boondocks
    Yeah, I do understand the grounding logo. Just wasn't sure if necessary.

    Okay.....

    So since my 220V only has 2 hots, and a "Return" wire, it's not grounded
    through the house wiring you're saying ?? I thought this was the ground :confused:
    Every thing I found online said it was.....

    I didn't have to ground my 220V air compressor separately.
    Just hooked it up with the 3 wires to the Dryer outlet. I'm confused.....

    Thanks so far sparky's.
     
    Last edited: Aug 4, 2011
  8. K5JMP

    K5JMP Veteran Member Lifetime Gold Member

    it's a safety thing.. in case for some reason the chassis of the machine has a voltage on it.
    you can sometimes get up to 60VAC on a "return" wire by itself.. meaning potential to earth ground..
     
  9. High Country Z

    High Country Z Veteran Member

    It's for safety, otherwise you could be come the ground when you operate the equipment.
     
  10. Aceshigh

    Aceshigh Veteran Member Lifetime Gold Member

    26,757
    1
    Apr 9, 2001
    Boondocks
    So .....

    My dryer, My Compressor, and anything else I run on my 220V outlet that doesn't
    have a 4th separate wire outside of the 3 wire pack is NOT grounded ??

    WTF......how is this code acceptable?? :eek: :confused:

    What does the return wire do in the 220V wiring ??
     

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