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jackgerd 11-05-2008 09:57 AM

240v Welder powered by portable generator
I like "MRJChannahon" have a 240v MIG welder (175 Lincoln Pro)and want to run it off my 15K gasoline generator.
The welder has a 3 prong (2 hots & a ground) but the Gaurdain 15K has 4 prong receptacle.

I have read a lot of the discussions about this on this site but I'm not able to get my welder to work.

I made a jumper from the 3 prong welder to the 4 prong receptacle on the generator. I have used the 2 hots and ground and I've also tried the 2 hots and the neutral but neither work.

I listened to "jrclen" and done as he has discussed but still not able to get the welder to work.

I thought my 15,000w generator would run my 50 amp welder?

Any help with this would be much appreciated.


J. V. 11-05-2008 10:21 AM

Have you verified that the welder is indeed outputing the correct voltage. Have you measured the voltage output?

The generator is designed with a four wire output. 2 hots, 1 neutral and 1 -Grd. Your welder does not require the neutral. It requires the 2-hots and the 1-grd.
How are you connecting a three prong plug to a 4 wire recept? Are you trying to connect the welder directly to the generator? Are you feeding a generator panel? When you say it will not work, what exactly do you mean? Does it trip the generator breaker? Do nothing? Explain what "does not work" means and we can help.

Have you tested your welder on a known good receptacle? What size and NEMA rating is the receptacle on your generator? If the welder is getting 240 volts it should work if the welder is proved to be in good working order.

jackgerd 11-05-2008 10:56 AM

I have not measured the voltage output of the welder. I can plug it into the shop receptacle (2 hots & a ground) and the welder works fine on all the heat settings so I'm assuming it is OK?
The two hots and ground is what I'm using from the welder to the generator. I have a jumper (extension cord) from the welder to the generator. the welder 3 prong male plugs into the jumper 3 prong receptacle female box and the jumper 3 prong male (two hots and groung)plugs into the generator female panel receptacle. I'm not using the neutral on the generator. The Welder will arc but it only will puddle weld on the hgighest heat setting, its acts like its not getting enough power from the generator. The generator manual says the receptacle on the generator is: "120/240 volt AC, 50 Amp Receptacle - Supplies electrical power for the operation of 120/240 Volt AC, 50 Amp, single-phase, 60 Hz, welder or motor loads".
The cord on the welder manual says it is a 3 prong plug (NEMA Type 6-50P) and the welder works fine when plugged into the shop wireing.

jerryh3 11-05-2008 11:18 AM

Have you tested the voltage at the adapter cord you made? Are you sure you're getting 240V across the two hot slots?

jackgerd 11-05-2008 11:34 AM

No I haven't I'll need to buy me a meter.

jerryh3 11-05-2008 12:31 PM

Compare the reading with the chart:
Make sure you are getting 240V between the X and Y terminals of your 6-50R.
I'm assuming you went from a 14-50P to a 6-50R. Right?

joed 11-05-2008 01:37 PM

What size cable is the cord? How long is it?

jackgerd 11-06-2008 07:56 AM

240v Welder powered by portable generator

Thanks for the link to the NEMA chart.
I looked at all the connections I've got and this is the way it is lied out:

Welder - has a 6-30P
Extension cord - to accept welder has a 6-30R


Extension cord is less than 10 feet long and I think is a 6/3 (only 3 wires)? I told the electric store what I was doing and this is the wire they sold me.

Extension cord - for plugging into portable generator is a 14-50P but I'm not using the neutral as I donít have a wire for it. The plug is such that I can actually leave the neutral prong out of the plug. I have left it in and jumped the ground across both with still no luck of getting the welder to work.

Note: I have taken my RV that has a 14-50P and plugged it into my generator and then turned on the two air conditioners that the RV has and the generator and other appliances worked just fine?

I hope to get a meter today and do some voltage testing.

J. V. 11-06-2008 10:48 AM

Sounds like the generator to me, or your connections. When you take the output voltage measurement, try to do it loaded. Get someone to weld (try to weld) while you measure. You do not need to jump out the neutral and ground. Just use the ground and abandon the neutral.

Since the welder works on house power it has to be the generator or the connections.

Stubbie 11-06-2008 12:23 PM

Your welder works but only puddles. When the generator is plugged into your rv it will power the a/c. If the a/c is not 240 volt you have not proved you have both hot legs. My guess is you have lost one leg of the power source either a generator fault or a open in your cord connections.
If I remember correctly some generators have selector switches for the 50 amp receptacle might check and see.

joed 11-06-2008 01:38 PM

loosing one leg of a 240 volt ciruit would make it an open. There would be no voltage.

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