GFCI and welder

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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?
Reply: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
Reply: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?
Reply:Originally Posted by rlitmanGFI'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?
Reply: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"http://www.farmersamm.com/
Reply:Originally Posted by farmersammThis 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
Reply:The darn things are so finicky that they try to outguess you. They blow at the slightest provocation
Reply: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.
Reply: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).-MondoLast edited by Mondo; 09-08-2008 at 01:51 PM.Reason: Minor Technical CorrectionsMember, AWSLincoln ProMIG 140Lincoln AC TombstoneCraftsman Lathe 12 x 24 c1935Atlas MFC Horizontal MillCraftsman Commercial Lathe 12 x 36 c1970- - - I'll just keep on keepin' on.
Reply: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.