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Old 05-18-2008, 10:30 AM   #1
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240v Welder powered by portable generator?


I just bought a 240v MIG welder and want to run it off my 7K gasoline generator.
The welder has a 6-50P plug (three prong), drawing 20 amps or less and the generater has an L14-30R receptacle. The generator L14-30 ground connection is wired into a line leading to the frame & ground lug on the generator and is NOT connected to the generator's AC neutral wire.

My question is whether to wire the welder's ground prong to to "neutral" or the "ground" prong on the L14-30? If I'm correct/safer to wire it to the "ground", do I then have to ground the generator via plumbing or an earth rod to be able to use the welder?

Thanks!

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Old 05-18-2008, 08:59 PM   #2
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Originally Posted by MRJChannahon View Post
I just bought a 240v MIG welder and want to run it off my 7K gasoline generator.
The welder has a 6-50P plug (three prong), drawing 20 amps or less and the generater has an L14-30R receptacle. The generator L14-30 ground connection is wired into a line leading to the frame & ground lug on the generator and is NOT connected to the generator's AC neutral wire.
Are you sure this is correct? Since you are using the generator as defined as a Separately Derived System, (SDS), having no connection to your service. You would need to bond, (at a single point only), the Neutral to the Equipment Grounding Conductor (EGC), at the first or main disconnect for fault clearing. If not, and your welder were to have a ground fault and there is no path to the grounded conductor, (Neutral), the generator chassis would become energized.

I would first make sure this is correct before hooking the welder up.

Quote:
My question is whether to wire the welder's ground prong to to "neutral" or the "ground" prong on the L14-30? If I'm correct/safer to wire it to the "ground", do I then have to ground the generator via plumbing or an earth rod to be able to use the welder?

Thanks!
If your generator is setup properly then you would use the ground only not the Neutral for your welder. You can run a Grounding Electrode Conductor, (GEC), to a cold water pipe and terminate the connection only at the Neutral to ECG bonding point.


This is a very controversial subject and you'll likely get some very different answers depending on who you ask. However, this is my understanding and would seem to me the safest solution to prevent shock hazards...

Good Luck

KC

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Old 05-18-2008, 09:46 PM   #3
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240v Welder powered by portable generator?


Yes, I'm certain that the welder plug type and amperage and the generator receptacle type and power capacity are correct. The information that the "ground" in the receptacle is wired directly to the generator frame and ground lug but is NOT connected to the AC neutral wire comes right out of the owner's manual (for what that's worth).

I've read other's remarks about 220v welders with a 20 amp draw that have 50 amp plugs seeming wrong, but it seems that several welder brands in this capacity have these plugs.

It would be a hassle, but I could attach the generator's ground lug to some plumbing or a ground rod, either of which would seem to complete the ground circuit (although that may not be the peoper terminology).

Thanks very much for the very detailed answer.
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Old 05-18-2008, 10:44 PM   #4
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240v Welder powered by portable generator?


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Originally Posted by MRJChannahon View Post
The information that the "ground" in the receptacle is wired directly to the generator frame and ground lug but is NOT connected to the AC neutral wire comes right out of the owner's manual (for what that's worth).
This does not mean that there is no bonding jumper since they are refering to the recepticle which would never be wired that way. They want to be sure you don't have multiple bonding locations.

What is the model generator you have. I would be curious to read that passage in the manual to be clear.

Quote:
I've read other's remarks about 220v welders with a 20 amp draw that have 50 amp plugs seeming wrong, but it seems that several welder brands in this capacity have these plugs.
Yes, you'll have to change the welder plug to an L1430P without using the Neutral.

KC
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Old 05-18-2008, 11:28 PM   #5
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240v Welder powered by portable generator?


Hi Ken,

The generator is a Jin Long JL7000DX. It's one of those recent Chinese imports using engines apparently being made with Honda machinery (since the motor parts are interchangable with Honda).

Assuming you won't be able to find the owner's manual on line (although Jin Long does have a web presence), here's EXACTLY what the manual says:

"GENERATOR GROUND CIRCUITS - TIGER portable generators have a system ground that connects generator frame components to the ground terminals in the AC output receptacles. The system ground is not connected to the AC neutral wire.

Local regulations, codes, or laws may require that the ground system be connected to the AC neutral wire. If the generator is tested by a receptacle tester, it will not show the same ground circuit condition as for a home receptacle.

If local regulations, codes, or laws require the system ground to be connected to the AC neutral wire, consult a qualified electrician or electrical inspector. Provide him with the electrical wiring diagram in this manual.

The ground terminal can be used to earth the generator or bond the frame of the generator to a frame of a vehicle, but only if it is required by local law or electrical code. Before using the ground terminal consult a qualified electrician or electrical inspector for regulations in your area."

Under the "CONTROLS" section of the manual, you find the description of the "GROUND TERMINAL" (showing an exposed bolt end sticking out attached to the generator frame) as follows: "The generator ground terminal is connected to the frame of the generator, the metal non-current carrying parts of the generator, and the ground terminals of each receptacle."

So there you go... It's actually written in better English than many of the Chinese imports we receive, but unfortunately, good grammar & syntax don't automatically equate to technical accuracy.

Thanks so much for your interest and assistance.
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Old 05-19-2008, 09:25 AM   #6
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240v Welder powered by portable generator?


Quote:
Originally Posted by MRJChannahon View Post
My question is whether to wire the welder's ground prong to to "neutral" or the "ground" prong on the L14-30? If I'm correct/safer to wire it to the "ground", do I then have to ground the generator via plumbing or an earth rod to be able to use the welder?
This is getting unnecessarily confusing. First, there is no reason nor advantage to connect a portable generator to the earth through plumbing pipes or ground rods when connecting to a welder. Second, the real question has to do with opening the over current protection device on the generator, in case of a fault in the welder cord or the welder itself from line to line. Or in the case of an overload. This is all you need to worry about. The welder has no neutral. So the question is, will there be a low impedance (resistance) path to open the circuit breaker, in the event of a short circuit. There will be. So connect the third wire from the welder to the grounding "prong" on the generator. Not to the neutral.
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Old 05-19-2008, 09:45 AM   #7
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Thank you very much.

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Old 05-20-2008, 12:08 AM   #8
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So the question is, will there be a low impedance (resistance) path to open the circuit breaker, in the event of a short circuit. There will be.
How do you know that? Unless the plugs are GFCI protected, how can you be sure the EGC will open the overcurrent device if there is no potencial there?

Ground faults are cleared through the grounded conductor. If the EGC can't carry current for lack of potencial, then in a phase to case fault the chassis would become energized.

KC
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Old 05-20-2008, 09:26 AM   #9
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240v Welder powered by portable generator?


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Originally Posted by kencaz View Post
How do you know that? Unless the plugs are GFCI protected, how can you be sure the EGC will open the overcurrent device if there is no potencial there?

Ground faults are cleared through the grounded conductor. If the EGC can't carry current for lack of potencial, then in a phase to case fault the chassis would become energized.

KC
The EGC will clear ground faults. Why would you think it would not? That is the sole purpose of an EGC. GFCI protection has nothing at all to do with this.

A branch circuit (the welder cord) is not permitted to use a grounded conductor to clear ground faults. That is why we use 4 wire circuits on dryers and other 240/120 loads.
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Old 05-20-2008, 09:41 PM   #10
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The EGC will clear ground faults. Why would you think it would not? That is the sole purpose of an EGC. GFCI protection has nothing at all to do with this.
Are you sure you are an Electrician? That is totaly not what I said. I know what the ECG is for but how do you think it clears ground faults? Through the Grounded Conductor or (Neutral). That is why every main service panel has the Equipment Grounding Conductor, (EGC), BONDED, to the Grounding Conductor, (Neutral).

If it is not bonded at the main panel, there is no potencial, (voltage), present for the EGC to carry current. You will not see 120 volts across any hot and the EGC as you should. No voltage, No current carrying, No, opening of overcurrent devices.

The manual for his generator states:

"If the generator is tested by a receptacle tester, it will not show the same ground circuit condition as for a home receptacle."

This means that a testor will show there is an improper ground, because, it cannot detect any voltage between the EGC and the Un-Grounded conductors.

In that case, YES, GFCI, has everything to do with it.



Quote:
A branch circuit (the welder cord) is not permitted to use a grounded conductor to clear ground faults. That is why we use 4 wire circuits on dryers and other 240/120 loads.
Where did that come from? I said nothing about using the Neutral as a Ground. If you read my other post, you will see that I told him twice, in post 2 and 4 not to use the Neutral.

And, Yes there are 240/120 dryer installations where you can certainly use the grounded conductor, (Neutral), to clear ground faults.

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Old 05-20-2008, 10:12 PM   #11
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240v Welder powered by portable generator?


Yes Jrclen is electrician i can verify his vocher i did talk to him a bit with him.

There is the diffrence between the EGC and grounded conductors both have diffrent function there.

Merci,Marc
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Old 05-21-2008, 09:13 AM   #12
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240v Welder powered by portable generator?


Thanks Marc. Yes Kencaz I am an electrician. I have been for over 40 years. I am also a licensed electrical contractor. I have no idea what your level of knowledge is, so I tried to keep things simple for you and explain things in DIY language. I must have failed.

I think what you are referring to is the main bonding jumper, not the EGC. And I think you believe there is no main bonding jumper as is required by the NEC on any separately derived source.

I believe three wire dryer circuits were prohibited starting with the 2002 code cycle. Maybe earlier. I don't recall the exact cycle but it has been awhile now. Yes there are many left which are still in service because the code is not retroactive. That fact does not prove it is a desirable practice. I brought that up to help you understand the difference between a grounded conductor and an equipment grounding conductor.

The OP just needed a plain simple answer to his question. Connect the ground wire on his welder to ground on his generator, and not to bother with ground rods or water pipes.
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Old 05-21-2008, 05:42 PM   #13
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240v Welder powered by portable generator?


I again want to thank all who've attempted to help me with this issue. If it were straight, house wiring, I'd likely have had no questions, since I've done things like wire a 220v input from a portable generator outside to a transfer switch in the house that works very well during power outages. However, your collective expertise has been greatly appreciated by this amateur, since this project had issues that were unusual to me and not directly covered in the NEC manuals that I use.


Now, I get to start learning how to weld...

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Old 05-21-2008, 06:16 PM   #14
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Quote:
Originally Posted by MRJChannahon View Post
I again want to thank all who've attempted to help me with this issue. If it were straight, house wiring, I'd likely have had no questions, since I've done things like wire a 220v input from a portable generator outside to a transfer switch in the house that works very well during power outages. However, your collective expertise has been greatly appreciated by this amateur, since this project had issues that were unusual to me and not directly covered in the NEC manuals that I use.


Now, I get to start learning how to weld...

MRJChannahon
Generators are a little different animal than house wiring. But I'm glad you are all set. MIG welding is fun. And fairly easy.
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Old 05-21-2008, 09:56 PM   #15
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Are you sure you are an Electrician?
Where did that come from? See his post history. John is a regular and reliable contributor to this forum. His posts speak for themselves. Please show a little respect for the regulars here.

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Originally Posted by kencaz View Post
I know what the ECG is for but how do you think it clears ground faults? Through the Grounded Conductor or (Neutral). That is why every main service panel has the Equipment Grounding Conductor, (EGC), BONDED, to the Grounding Conductor, (Neutral).
Disagree. In a ground fault, i.e. fault between ungrounded/hot conductor and ground (as opposed to a phase to phase fault and yes I know that residential is split phase, thank you), the current flows back to the source via the EGC. You're confusing main bonding jumper, grounding electrode conductor and equipment grounding conductor. See NEC 100. Neither the ECG nor the grounding conductor [sic] are neutral. GFCI's work on the "current in=current out" principle. If the current leaving is in excess of 5mA of that returning, the device will trip. It doesn't need to know where the fault current went nor does it require an EGC to do so. Read article 406. Why do you think it is acceptable to replace older, ungrounded receptacles with newer grounding types that are fed from a GFCI w/o an EGC??

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In that case, YES, GFCI, has everything to do with it.
It must be getting late.

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And, Yes there are 240/120 dryer installations where you can certainly use the grounded conductor, (Neutral), to clear ground faults.
No, there are some appliances that require both 240 and 120 inputs (i.e. they do not have an internal transformer to create the 120 from the 240).

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