How to wire a 375 amp tig welder for my garage?

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Old 01-23-08, 11:16 AM
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How to wire a 375 amp tig welder for my garage?

Question, I have a 375AMP miller syncro wave Tig welder in the garage of my new house. I have a 200amp service panel and meter on the outside of my house. The welder will draw a maximum of 115 amps (Which I will probably never need). What would be the best way to run the needed power into my garage. The run would be approx. 30-40 feet through the attic space. Hope I described this right?


Thanks

Dale
 
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Old 01-23-08, 12:48 PM
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What is the duty cycle on that particular machine? A model number would help too.
 
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Old 01-24-08, 09:45 AM
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Welder

Originally Posted by ibpooks View Post
What is the duty cycle on that particular machine? A model number would help too.

Miller Syncrowave 300, S/N J8516429, it's an older unit built in 1985.

Rated Weld current: 300 amps, 32 volts 60% duty cycle

Max amp draw: 204 amps at 230V. This is with the machine maxed out at 375 Amps which I have never needed.

Max amp draw: 300 amps at 230 Volts is 120 amps this is the most I've ever needed.

Thanks

Dale
 
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Old 01-24-08, 02:25 PM
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Wow i am sure this is a serious sized welders i just read the model number and spec wowie

anyway here it is part of specs

Welder spec [ in PDF file ]

and just read that at max rating it will draw at 120 amp

IIRC there is a specal section related to welding circuits but unforetally i dont have all the detail how to do this properly normally i have a habit to spec by nameplate rating due one of my comuster he owned a welding shop and i follow the nameplate rating due his welder is pretty much on constant useage [ those welder is much bigger than the average homeowner welder size useally twice bigger than that]

I will ask Ben or Jon or Racraft [Bob] or John N. i am sure few others can pitch in this one as well.

let me get back here real quick the owner manual did mention the KW rating so and i will pretty much follow both KW and OP's mention of amp using for both Stick welding and other welding methold.

this welder is speced at 60% duty cycle so you know this is a very serious welding machine [ most home welder are useally are at 40% or smaller duty cycle ]

yeah this is a 12.8KW size but you can squeak by with 50 amp circuit but i rather wait until others join here and comfirmed with this details you will need more than just 50 amp circuit to handle this beast.

Merci, Marc
 
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Old 01-24-08, 03:18 PM
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This is really a huge machine for residential use!

The installation manual linked by Marc has a table on page 10 which gives circuit conductor sizes. For the 300A welder with no power factor correction on a 230V system, you need #1/0 copper hot conductors and a #6 ground and a 225A breaker. You actually can't install a 225A breaker in a 200A panel, so you'd have to drop the breaker size a bit.

I think these conductor sizes from the manual are a little oversized, so I'll check the actual calculation and post back in a little while.
 
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Old 01-24-08, 06:14 PM
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Way out side of my knowledge but doesn't he need to do a load calculation for his panel before proceeding.
 
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Old 01-24-08, 09:28 PM
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Ok i am back here now but to the OP i dont like to be a bearer of bad news but i crush few numbers and i did asked my freinds to confirmed this details if your primary side is 120amps and used the demand factor of .78 = 93.6 amp

this is pretty serious sized welder i dont recall see anyone useing that big of welder in resdential useage.

Anyway you may run into some issue with this because this is pretty powerfull unit and it will need a 100 amp circuit for this.

please disagree my last comment above this with 50 amp size.

there is a 100 amp breaker it can fit in your box and get 100amp non fused disconnect switch [ mantory safety reqirement] this circuit you can not add this in the exsting subfeed box at all you will trip the breaker by time you crank it up have it running even on low power setting you may get by but really only option is run that circuit driect to the main box and hook up from there or hevey up to 400 amp and leave the 200 amp to the house alone and run the 200 amp to garage.

hope this will help ya with some info you are looking for

Merci, Marc

If more question please do reply here
 
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Old 01-25-08, 10:09 AM
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I agree with Marc's calculation. The welder circuit should be designed for 100A. This means you will need to use #3 copper for the two hot conductors and #8 copper for the ground conductor. This applies if you use a wire type rated for 75C like THHN in conduit or SER cable. If you use NM-B "Romex" cable, then you need to bump up to size #2/2 with ground.

The breaker size should be a minimum of 100A and a maximum of 200A. Start on the lower end and if the machine trips the breaker you can increase sizes, but do not exceed 200A breaker size. Of course with the oversized breaker, the circuit may be used only for a welding machine not for other tools or subpanels, etc.

Also, the 100A rated disconnect switch at the point of use near the machine is mandatory.
 
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Old 01-25-08, 12:23 PM
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Originally Posted by oilhead110 View Post
Question, I have a 375AMP miller syncro wave Tig welder in the garage of my new house. I have a 200amp service panel and meter on the outside of my house. The welder will draw a maximum of 115 amps (Which I will probably never need). What would be the best way to run the needed power into my garage. The run would be approx. 30-40 feet through the attic space. Hope I described this right?


Thanks

Dale
My company just moved locations and I had the pleasure of installing 5 Lincon 375 machines, (similar to the Millers).

They are hefty machines and your POCO bill will probably double if you use it often.

What we did was run two 225A panels to feed all the welders. (about 100ft from the main service). They are 3phase 208 but the welders only need single phase. From there we used 125A 2pole breakers (bolt on), with #2 THWN and #8 for ground through 1" EMT to feed the 2pole 100A fused disconnects.

We use the machines quite often in the 350 range and have not had any tripps or overheat issues.

I don't do much residential so I am not certain if you could run 1"EMT through an attic, and that would be some heavy Romex if you went that route.

Here is a pic of our install:

http://www.imageviper.com/displayima...2607_13151.jpg


KC
 
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Old 01-25-08, 07:42 PM
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may i ask if your installations were inspected?
Originally Posted by kencaz View Post
My company just moved locations and I had the pleasure of installing 5 Lincon 375 machines, (similar to the Millers).

They are hefty machines and your POCO bill will probably double if you use it often.

What we did was run two 225A panels to feed all the welders. (about 100ft from the main service). They are 3phase 208 but the welders only need single phase. From there we used 125A 2pole breakers (bolt on), with #2 THWN and #8 for ground through 1" EMT to feed the 2pole 100A fused disconnects.

We use the machines quite often in the 350 range and have not had any tripps or overheat issues.

I don't do much residential so I am not certain if you could run 1"EMT through an attic, and that would be some heavy Romex if you went that route.

Here is a pic of our install:

http://www.imageviper.com/displayima...2607_13151.jpg


KC
 
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Old 01-25-08, 08:05 PM
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Originally Posted by sparky480 View Post
may i ask if your installations were inspected?
No, they have not been inspected. Do you see a violation?

KC
 
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Old 01-26-08, 01:16 AM
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I see several potential violations depending on your local code and just when the picture was taken.

1. The safety switch on the left does not appear to be marked as to what it supplies.

2. The air hose nozzle hanging on the safety switch.

3. The fluorescent tubes leaning against the center panel.

4. The center panel is not marked for its source nor its voltage and phases.

5. The "medallion" on top of the center panel should not be there.

6. The three phase conductors in the new panel are not marked.

7. There appears to be no neutral lead in the new panel although as long as there are only phase-to-phase loads this may not be a violation.

8. It appears that the isolated neutral bus is being used for equipment grounding. This may be acceptable if there are no phase-to-neutral loads AND the bus is bonded to the main panel.

9. There is a lot of "junk" in front of the panels. Unless this is ONLY a roll-away cart holding tools and supplies for the installation of the new panel (and will be removed when the new panel is finished) it is in violation of the clear access rule.
 
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Old 01-26-08, 11:19 AM
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Originally Posted by furd View Post
I see several potential violations depending on your local code and just when the picture was taken.
1. The safety switch on the left does not appear to be marked as to what it supplies.
I have never seen a disconnect show that. They are now marked with panel and breaker location ie: F-1 etc...

2. The air hose nozzle hanging on the safety switch.
Temporary, new air line pipe has been installed.

3. The fluorescent tubes leaning against the center panel.
Again, temporary.

4. The center panel is not marked for its source nor its voltage and phases.
Marked only as Sub F or E. Voltage and Phase information is inside.

5. The "medallion" on top of the center panel should not be there.
OK, got me on that one...

6. The three phase conductors in the new panel are not marked.
They are now marked Blk, Red, Blue.

7. There appears to be no neutral lead in the new panel although as long as there are only phase-to-phase loads this may not be a violation.
The panels are for Single and 3 phase only.

8. It appears that the isolated neutral bus is being used for equipment grounding. This may be acceptable if there are no phase-to-neutral loads AND the bus is bonded to the main panel.
As, above.

9. There is a lot of "junk" in front of the panels. Unless this is ONLY a roll-away cart holding tools and supplies for the installation of the new panel (and will be removed when the new panel is finished) it is in violation of the clear access rule.
Temporary, There is only a steel table about 4Ft from the panel but has clear access.

Hope that clears some things up.

KC
 
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