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Stick welders and input amperage

Discussion in 'The Hokey Ass Message Board' started by tubman, Jan 11, 2014.

  1. tubman
    Joined: May 16, 2007
    Posts: 5,594


    Again, I've tried a search, and can't find what I need to know. My new shop has 50 Amp service (it's in a storage complex, but it does have 220 Volts). I put in a 20 Amp 220 drop so I could run my 220 Hobart Mig and my 220 air compressor (not at the same time; I'm getting old). Back in the day, I use a variety of 180 to 225 stick welders, and got to be pretty good at it. My last stick welder was a Miller 225, and I let a friend use it for the last 10-15 years. Now, he no longer needs it, and I am going to get it back. As a 225 stick welder, it needs a 50 Amp 220 circuit. I wired the drop myself with a short run of 10 Gauge wire, so I know I can probably replace the 20 Amp breaker with a 30 Amp.

    My question is : Is this enough current to run the 225 Miller? As I remember, I used to run about 125 Amps on the secondary when doing 1/8" to 1/4" plate. I never remember running over 200 Amps any time. I may blow a breaker once in a while, but I can live with that.

    On another thought, I see there are a lot of 110/220 inverter based units for less than $500 that will stick weld up to 160 Amps, plasma cut, and even Tig. Are these for real? Maybe one of these may be a better choice for me. Is the inverter technology that much better. I would be willing to wait a couple of years and go with the old Miller if there is something good coming down the line.

    I really feel more comfortable stick welding heavier steel, and would like to know what road to go down.
  2. 50 Amps pull on 10ga wire into a 30 amp breaker sound right to you ?
    Me neither.

    Yea inverter technology is superior and much smaller but there's more to go wrong with it when it goes.
  3. aaggie
    Joined: Nov 21, 2009
    Posts: 2,531


    You need 50AMP breakers and at least #8 wire. Fire insurance would be nice too.
  4. Engine man
    Joined: Jan 30, 2011
    Posts: 3,476

    Engine man
    from Wisconsin

    10 gauge wire is fine on 30 amps according to the national electrical code. Depending on the insulation type, it can carry up to 40 amps. A 30 amp breaker is designed to trip at 80% of rated current or 24 amps. I've welded with my 225 Miller Thunderbolt using a 30 amp dryer circuit many times. Using 1/8" stick I'm usually around 110 amps so it's around 1/2 the maximum rating for the welder so it would use 1/2 the current. The 50 amp circuit called for to operate the welder would be 120% of the actual current meaning the actual full load primary current would be just under 42 amps. 1/2 of that is 21 amps so the 30 amp breaker should handle it with ease. You could also use 3/32 rod and lower current.

  5. Roger Walling
    Joined: Sep 26, 2010
    Posts: 1,149

    Roger Walling

    Why would you deliberately under wire anything to save a few bucks?

    It would be like making a 6" long swimming pool, after all, you would would be covered with water all over, so what difference would a 50" pool make?
  6. charlieb66
    Joined: Apr 18, 2011
    Posts: 549


    Better find a licensed electrical contractor to do the work. Quoting a post from the HAMB will not solve your insurance problem when you have a fire. Self engineered electrical work is traceable after the fire is out.
  7. Firstly, are you sure the service is 50 amp?? Around here, 100 amp is residential norm. Mine own house has 100 amp coming in.

    Second, 50 amp SERVICE is NOT 50 amp to your welder, unless you have shut everything else OFF.

    Third, ask a firefighter how long it takes to get to your unit. This will determine how burnt it's gonna be.

  8. Ebbsspeed
    Joined: Nov 11, 2005
    Posts: 5,461


    It would be real hard to cover me with 6 inches of water.

    He initially wired it for his air compressor and Hobart MIG. Now he wants to replace the 20 amp breaker with a 30 amp in order to use his welder to the maximum capacity that a 30 amp circuit will support. According to the NEC 10 gauge will support 30 amps, and that's the size of breaker he said he was going to use. The only issue will be that he won't be able to use the welder to full capacity.

    All you doom and gloom guys are touting fire insurance, meteors raining down, dogs and cats sleeping together, hire a professional electrician, blah blah. You can certainly tell who is afraid of electricity.
  9. Ole don
    Joined: Dec 16, 2005
    Posts: 2,915

    Ole don

    When welding, go slow on the machine and let it cool a lot. Unless you have a huge project, the amount of time actually pulling amps is very little.
  10. tubman
    Joined: May 16, 2007
    Posts: 5,594


    This isn't my first waltz with this sort of thing. I have wired 3 shops before this one. I do know what gauge wire to use for what voltage, amperage, and length of the wire run. I have a 1 foot drop right off the fuse box with 10 gauge wire in a conduit, and according to the 4 or 5 tables and calculators I have used, 10 gauge is more than sufficient in this application (one calculator even said 14 gauge would be OK for short run such as this). Also, a circuit breaker is designed to do exactly what it's name says, break the circuit if it's rating is exceeded.

    I didn't wire my shop the way I did to save a couple of bucks; I did it to suit the service to the unit and the equipment I had at the time. I was quite surprised when I got my old Miller back, and would like to be able to use it.

    I guess I could have been clearer with my questions.

    1. Has anyone had experience using a stick welder with less than rated primary amperage; it seems at least a couple of you have had success doing so.

    2. Are the new inverter based units (which don't require the input amperage of a transformer unit) that much of an improvement over the "buzz-boxes" to warrant getting one and selling the old Miller? I have been looking at an Everlast 140 unit, and it seems to be the real deal. Although it's Chinese, it comes with a 5 year warranty, and 99% of the reviews I read seem to indicate that both the unit itself and Everlast's customer support are top notch. It even has the capability to TIG, although I don't believe I'll get into that given my advanced years.
    Last edited: Jan 12, 2014
  11. dirty old man
    Joined: Feb 2, 2008
    Posts: 8,892

    dirty old man

    The inverter welders are much more efficient than the old transformer units. All of mine are the old type, stick, mig, and tig.
    But as inefficient as they are, at 76 with not a lot of welding going on anymore, I'll live with them!
    What you are proposing will work as long as you take care to not turn it up too high. One trick: use 6011 rods, as a 1/8" 6011 uses approx. 90 amps and the 6037 uses 125. More splatter and not as smooth a bead, but better penetration.
    One caveat: Better check your rental/lease agreement on that storage unit about welding in there.
  12. whtbaron
    Joined: Sep 12, 2012
    Posts: 571

    from manitoba

    I have a 150 amp service and 2 220volt outlets, one is 40 amp, one 50 (correction, I checked and they are 30 and 40. I use the 30 for the air compresser and the 40 for the welders). I have 2 stick welders, a Forney 225 and a Sears 230. If I'm welding I use the 40 amp outlet. The 30 amp breaker will trip on a large job. I've also kept the drops short, less than 2 ft of 8 guage wire, and the welder is plugged in directly (no extensions)... the longer the distance from the breaker to the job, the more problems you will have with light breakers. I would recommend a new drop with 8 guage wire and a 40 amp breaker for your stick welder.
    Last edited: Jan 13, 2014
  13. Ebbsspeed
    Joined: Nov 11, 2005
    Posts: 5,461


    Please explain. I understand that there will be more voltage drop on a "longer" circuit, but not sure how light breakers play into that.
  14. Engine man
    Joined: Jan 30, 2011
    Posts: 3,476

    Engine man
    from Wisconsin

    The power used is the product of the voltage x the current. If the voltage is low, the unit will draw more current to keep the power the same.
  15. If the tag placed on the machine by the manufacturer under guidance and recomendations of UL say it should have a 50 amp supply then that's what it's supposed to have.

    Plug it into you ass if you want but if something goes wrong you'll know where to look for answers. Something like - not welding correctly, you crap falls apart, your welder takes a dump, your breaker pops, who knows what could go wrong- but the first step in trouble shooting it is going to be "check for proper input to the machine" and you won't have it.
  16. Pete1
    Joined: Aug 23, 2004
    Posts: 1,954

    from Wa.

    1- Yes, you can run a big welder (50a) on a small circuit (30a).
    Now the gloom and doom aspect. It is not legal because you will have to modify
    some part of the input circuit. A 30a outlet has a certain configuration. A 50a power plug
    on a welder has a different configuration that does not match. Modifying any of these ends
    so they match is illegal and even if you start a fire with a torch or a misplaced cigarette
    the insurance co. will say no to your claim because they will find non code electrical mods.
    2- Yes, inverter welders are more efficient. They are usually smaller in size for their rating
    if portability is a requirement. I have a 300a Miller and it is no bigger than a standard
  17. inline 292
    Joined: Aug 25, 2006
    Posts: 296

    inline 292

    I would wire it to what you have available now & run a bead using 3/32 rod while a buddy holds an Amprobe arond the outlet box wires. IF that seems to be within your power supply limits, try a 1/8 rod at its appropriate setting. if its over your systems limit, the breaker should pop or your buddy tells you to stop there.

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