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Hey guys, wiring in a welder question

Leitnin

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Joined
Mar 11, 2008
Messages
31
FEEL FREE TO MOVE THIS IF IT SHOULD BE SOMEWHERE ELSE, THANKS


Well, I've been reading just about everything I can read on putting crazy giant tools into my garage.

wait...I mean I looked at Oldcarguys garage one time on here.

Anyway, I've been trolling for a little while and I think this is a good crowd for my questions.

I am picking up a used Miller 340a/bp welder tomorrow (manual for a 330 looks the same, and until Its delivered I won't have the serial number to look it up any differently). It has a pedal, water valve, gas valve etc. Needs the rest of the torch (only has torch body), some water flow, and a bottle/regulator.

My question at first is more about wiring it in to my house.

I've looked into it, and my main panel is on the outside of my garage wall, with a nice big 200A breaker on top. So I think I'm good on having the power for this 850 pound monster.

Now, I'm not going to be running it to max capacity for sure, and It seems like 100A is an okay number for protecting the circuit while still not tripping it all day long.

I was wondering what the best way to wire this thing in was. I've been looking at the manual for days now, and it isn't 100% clear to me.




Here is what I'm looking at:

1. cut a whole in the drywall behind where the main panel is.
2. Using #2 wire with #6 ground, wire from a 240 breaker in the main panel to a disconnect panel.
3. Wire the welder into the disconnect panel.

so. questions are,

what breaker do i really put into the main panel becasue i didn't think you could put a 100A breaking in there?

What is the appropriate wire size and type to run to a disconnect panel merely feet away if that is even an acceptable place to put it (ive heard a lot about de-rating the machine due to duty cycle, but at the lower levels where i will be running it, it has a 100% duty cycle.)

what goes into the disconnect panel to "protect" it? another 100A breaker? nothing? something else.

I've had a lot of trouble researching this type of thing. I have run new dedicated 20A circuits for over-the-range microwave installs to code, but I'm not familiar with this.





I apologize for the length of the post, but I like to be as clear as possible.

Thanks guys

-Dan

p.s. I know someone is going to say Hire an electrician and i will if need be, but with a little guidance I'm sure I can handle it. I taught myself how to build engines and motorcycles from the frame up, I can probably do this :)
 
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nissan_crawler

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Jan 12, 2008
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Wichita, KS
Do you know what amperage it draws? I have no clue when it comes to wiring in a 100 amp circuit, if that's what it truly takes.
 
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Leitnin

Active member
Joined
Mar 11, 2008
Messages
31
input at rated load:

200V = 110A
230V = 96A
460V = 48A <-- not happening

Input conductor and wire size:

200V and 230V both listed at #2 with #6 ground

Fuse size in amperes:
200V = 200A
230V = 175A <--im not going anywhere near max power, so I think 100A breaker/fuse wouldn't trip all the time?


http://www.millerwelds.com/om/o340p_mil.pdf

Manual online for the 330a/bp welder. appears the same as the 340a/bp which is very poorly documented.
 
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Leitnin

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Mar 11, 2008
Messages
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96 amps should be at an output of 300 amps. that is well above where I will be welding. it says to fuse for 175 however I have read several forums where people have installed with 100A or LESS with no problems.

asuming I wanted to protect the circuit at 100A, what would I do regarding wiring?

is a 100A breaker in the main panel wired to a panel that just connects them okay, or does it need a second breaker in the "sub"panel?

the manual looks like the disconnect is just a hookup, without "fuse" or "braker"
 

Merkava_4

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Dec 26, 2007
Messages
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Location
Clovis, CA.
96 amps should be at an output of 300 amps. that is well above where I will be welding.

Hell yeah! I don't think I've ever had the machine set over 140 amps and that's with E7024. Usually I'll run E7018 between 100 and 125 amps with the 3/32" size. A 100 amp breaker will do it!
 
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