GFCI and welder
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Thread: GFCI and welder

  1. #1
    Join Date
    Oct 2006
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    49

    GFCI and welder

    I tried for the first time tonight to use my 120V Clarke 135 amp spool gun mig welder off my 8000 watt continuous generator (13,500 surge). As soon as I pulled the trigger trying to start an arc the GFCI blew on the generator. It is a 15 amp outlet. The welder was plugged in with no additional cords.

    The push button breaker above the outlet didn't blow so I don't think it was too many amps. The welder was not set on max either. I was using the same settings earlier on a 15 amp outlet from the shed and had no issues. Do GFCI's not like welders or is this a problem with my generator?

  2. #2
    Join Date
    Jun 2008
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    41

    Re: GFCI and welder

    I would say the problem is with your generator, all the outlets in my garage are GFCI and my Lincoln Weldpac 100 doesn't trip them.

    Ed

  3. #3
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    Jul 2008
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    Re: GFCI and welder

    GFI's work, by ensuring that the power traveling in the hot wire, is exactly equal to the power in the neutral. Any variation between the two, means that power is leaking to another ground path. So, was your welder "ground" poorly connected, or was the part you were welding well connected to earth ground instead?

  4. #4
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    Re: GFCI and welder

    Quote Originally Posted by rlitman View Post
    GFI's work, by ensuring that the power traveling in the hot wire, is exactly equal to the power in the neutral. Any variation between the two, means that power is leaking to another ground path. So, was your welder "ground" poorly connected, or was the part you were welding well connected to earth ground instead?
    Ditto. What this can mean is that things are only slightly less than ideal. These will trip with milliamps. They are designed to go beyond the typical fault scenario. It could mean more tho maybe. Sometimes they are really trying to tell you something, most times it's nothing more than a nusance trip. You won't know untill you run the full gamut of checks.

    One question is have you run this machine off any other GFCI at all ?? A GFCI in the conventional setting and not a generator setting.

    Another question is, are your ground and supposed neutral tied together inside your welder? That can also be problematic with a metallic genset and a metallic tool.

  5. #5
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    Aug 2008
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    Re: GFCI and welder

    This wil draw a lot of negative comments.

    I weld outside. I also do my own wiring.

    I tried doing it the "right" way, and used interrupters. Turned out to be a real mess.

    The darn things are so finicky that they try to outguess you. They blow at the slightest provocation.

    I work on wet grass in the morning because of the dew, or because I regularly wet down the area to prevent a grass fire in the yard. I had to give up on the GFCI because it constantly opened the circuit.

    I suppose a GFCI is a good thing when you're using a toaster in the bathtub, but other than that, they're a pain in the butt.

    If you're stuck on the GFCI, go to a higher amperage rated breaker, or ask you're supplier if they have a breaker with a delayed action.

    Starting amps are sometimes a lot higher than rated amperage of the tool/machine. You need the extra oomph to start.

    I'm gonna hear about this
    "Any day above ground is a good day"

  6. #6
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    Re: GFCI and welder

    Quote Originally Posted by farmersamm View Post
    This wil draw a lot of negative comments.

    I weld outside. I also do my own wiring.

    I tried doing it the "right" way, and used interrupters. Turned out to be a real mess.

    The darn things are so finicky that they try to outguess you. They blow at the slightest provocation.

    I work on wet grass in the morning because of the dew, or because I regularly wet down the area to prevent a grass fire in the yard. I had to give up on the GFCI because it constantly opened the circuit.

    I suppose a GFCI is a good thing when you're using a toaster in the bathtub, but other than that, they're a pain in the butt.

    If you're stuck on the GFCI, go to a higher amperage rated breaker, or ask you're supplier if they have a breaker with a delayed action.

    Starting amps are sometimes a lot higher than rated amperage of the tool/machine. You need the extra oomph to start.

    I'm gonna hear about this
    You know it!!!!!!

    Anyway, I have to agree with you. If I would run my maxstar 150, it would start on the soft side, and rarely trip a breaker, or a GFI. But on the boats in the harbor, for whatever reason, the marine panels' GFI were so picky, i would just bypass the damn things. Nothing like being up 20ft over the deck, and then have to climb down to reset a GFI. Start amps on my mini mig (Lincoln 100) would trip a GFI in a heartbeat. I would remove the GFI, plug in a regular receptacle, and then go to town, and replace the GFI when I was done. I have also killed a GFI trying to run my welder on it.
    I think she is Bi-polar. She is a bear sometimes. Does this make her a BiPolar bear????

  7. #7
    Join Date
    Sep 2007
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    Re: GFCI and welder

    The darn things are so finicky that they try to outguess you. They blow at the slightest provocation

    Your are right here, but then they have to be. 250 milliamps through the heart is enough to stop it, or send it into fibrillation. They are a lot better now than when they first came out - they wouldn't even run a hair dryer then. But some equipment will have leakage currents that are not dangerous, but will not run with a GFI.

    I bought a cement mixer when I built a house not long ago. I wasn't a cheap one from Lowe's either. I tried plugging it straight into the receptacle and not using the extension which sometimes works due to capacitance, but it still wouldn't work. It would run until it the mixer got a little wet and then trip. I had to run another circuit on the temp service pole to run it, but I also ran a ground wire from the mixer frame straight to the service ground rod. As soon as the masonry work was done I took the box down leaving only the GFI.

    I use to work at a paper mill and taught a basic electrical course for all the new hires in our department. I told them that in all the years I had worked with high voltage the closest I had ever come to seeing someone electrocuted was on 120 volts with an extension cord working in a wet environment.

    While we are on the subject of water and electrical stuff I will let you in on a little trick you can use a stick welder on you might not know. We were coming up after a shut down and the night before we were to start up the chip yard I found out my mechanical counterpart had our plate feeder ( under the huge chip pile that fed chips onto a conveyor that fed our digesters ) pressured washed and naturally they didn't cover the motor. The job was not on the shut list which was a real no no at our mill.

    I immediately sent an EI tech to megger the motor and when he came back his face was white - it was reading a dead short. I then went straight to the mechanical guy to tell him what a predicament he had put us in. The motor was a 350 HP or better and it would have been a riggers nightmare to change , steel to be cut, etc. I wanted him to get his A$$ chewed so he wouldn't do this again.

    I had the mechanics pull a BobCat with extra long leads to the mouth of the chip tunnel. I put about fifty amps through the windings to start with and then had the night shift guy raise it a little alternating each winding so it would dry out. The next morning I went in the tunnel and megged the motor. It was warm and megging like it just came off of the shelf. It is not the current that fries a motor when it is started wet but the voltage that Arch's across the windings.

    Well, we came up on time which is a real political thing at a paper mill. Our department manager, who had been real worried when he found out what I was doing, had a big smile on his face, and I was hero for a day. A day is about all that you can be a hero at a paper mill because well, " Stuff Happens'. Well, the motor was still running when I retired two years later and it never got washed down again without about 10 layers of plastic.

  8. #8
    Join Date
    Oct 2006
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    49

    Re: GFCI and welder

    Sound like a stop at Lowes on the way home is in order.

    I will get the stuff to take power from the 30 amp 4 prong non-GFCI generator outlet and wire it up to a conventional 3 prong 50 amp female welding outlet. I already have a 4 foot pigtail with the male 50 amp welding outlet connected to a female 120 plug.

    Thanks for the info. I'll leave the GFCI's in place for the other plugin stuff. Maybe it is a problem with my welder so I can try it with a household GFCI to make sure. Thanks for the suggestion.

  9. #9
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    Re: GFCI and welder

    If you are tripping a GFCI with a 120V welder then there is something wrong with the welder or the neutral and ground system in your generator, shop or home. The GFCI should not trip while welding unless some of the electrical energy is not returning to the supply circuit properly via the neutral conductor. Neutral-to-Ground short comes to mind as a most likely cause.

    FWIW: The last time I checked the specs a Ground Fault Circuit Interrupter must remain on if the current difference between Hot and Neutral is less than 4 ma (milli-amps). The breaker must trip if the difference is 6ma or more. (Many manufacturers list this trip specification as 5ma +/- 1ma). There is a tolerence range of 4ma to 6ma which is a sort of no-man's land. The breaker may either trip or remain on if the difference is in this range. This sometimes makes them seem finickey, especially if you have two from different manufacturers and they behave a little differently when the same devices are connected to them. The reason for the range is the same reason for all semi-conductor devices; there is a rise and fall time for voltage or current changes no matter how abrupt, and there must be an allowance for electrical noise.

    I often connect my Lincoln MIG-140 to a GFCI protected recepticle. This is a good recepticle and the HOT, Neutral, and Ground wires are correctly connected to the recepticle and at the panel and all test good. I have a double gang duplex recepticle box welded to my welding table with two GFCI duplex recepticles installed. The ground wire from the feed is connected to the ground terminal of one of these two GFCI recepticles making the box grounded through the mounting lug of the recepticle assembly. The other recepticle assembly is then grounded from the box through it's mounting lug. Becauses the box is welded to the table the table is therefore also grounded through the house wiring to the panel.

    I clamp a work piece on the table, clamp the work lead from the welder to the table (placing my entire house wiring grounds on the welding circuit at work clamp polarity) and weld away. It does not matter if I am welding with bare wire (DC Electrode Positive - Work Clamp Negative) or FCAW (Electrode Negative -Work Clamp Positive). I have yet to see the GFCI trip. I have tripped the 120V breaker at the main panel for over current when I let the wire stick, but that is not a GFCI type breaker.

    As I noted above: If you are tripping a GFCI with a 120V welder then there is something wrong with the welder or the generator, or if in a home or shop the neutral and ground system in your shop or home. A common problem is a Neutral-to-Ground short somewhere on the load side of the main panel. This is very difficult to check for because Ground and Neutral are tired together at the panel or ground stake. If you are working from a branch panel check to see if the load side ground and the load side neutral are tied to the same bus. You may need to call a qualified electrician who truely understands GFCI protection to troubleshoot and resolve the issue. (In theory any licensed electrician should be able to do this, but I have found not all electricians really understand how GFCI protection works).

    -Mondo
    Last edited by Mondo; 09-08-2008 at 02:51 PM. Reason: Minor Technical Corrections
    Member, AWS
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  10. #10
    Join Date
    Oct 2006
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    49

    Re: GFCI and welder

    Thanks for the info. I used my homemade connector to pull 110 off the 30 amp 240 on the generator tonight and it worked great. I need to do some checking with the gfci outlets and the welder.

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