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  1. #1
    Join Date
    Dec 2007
    Posts
    157

    Default Help! 30A Receptacle - 28A rated welder has a 20A plug?

    I have a plasma cutter, Spectrum 375 which is rated at 28A @ 115V and a Maxstar 150 STL which is rated at 28A @ 115V. Both have a 20A plugs from the factory.

    I am rewiring a panel in my garage and I wanted to provide outlets for each piece of equipment. As far as I know, there is no such thing as a 30A rated receptacle for that 20A plug (ground, verticle and a horizontal prongs).

    I could cut the cord and add a twist lock rated at 30A, but that then limits the portability of these smaller units which is why I purchased them. The welder is auto line sensing but I do not want to wire a 115V receptacle as 220V as someone down the road may inadvertantly plug in an incompatable device.

    At this point I am thinking of use the best quality 20A single recepatcle I can find with 10 gauge wire and a 30 amp breaker. The receptacle would be for this use only and I see no danger of plugging in a different 20A device. The weak link would be the receptacle if I crank up the A on the welder or plasma.

    I would appreciate any input that you have.

    Thanks

    John
    Valakas Construction, LLC

  2. #2
    Join Date
    Aug 2006
    Location
    N.C.
    Posts
    362

    Default

    John.... I have run my Maxstar 150S on a 30 ft. 10ga. ext. cord on a 20 amp breaker that also runs my computer and all the lights in my bedroom @ 90 amps. burning 3/32 7018's as fast as I could "load" them with no problems at all.....as far as a 30amp plug they do make them....for RV's....actually that is what I bought to make the 30ft. ext. from as it was only $30 and 30 ft. of 10/3 locally was $45.....I also run it on a 220v circuit using the 20amp 110 plug that the Maxstar came with... I made up an ext./ adapter cord from 50ft. of 12/3 with a 30amp 220v male plug and a 20amp 110v female plug... I have run it as high as 130 ish amps thru a couple of rods and have had zero problems.... I did mark the adapter cord on the female end as 220.
    George W. Bush was saving your butt whether you liked it or not!
    Fear is temporary, regret is forever
    HH210 with SG

  3. #3
    Join Date
    Dec 2007
    Posts
    157

    Default Thanks... but

    Hey Mike, Thanks for taking the time to respond.

    I have a good idea what can work as far as temporary solutions, but I would like to wire perminent receptacles for each piece of equipment which will allow the equipment to work at the maximum spec if I need it to.

    The plasma cutter can use more than the 20A the plug is rated at. It is rated at 28A @ 115V and 14A @ 230V. It seems that the idea was that for most applications you can use the 115V if you have a 20A outlet handy. If I want a full performance, I will need to wire a 20A 230V outlet - I just don't like the fact that you can plug 20A 115V appliance/equipment in to this outlet and fry it by mistake.

    The welder however is rated at more than 20A @ 230V. (28A @ 115V and 23A @ 230V - This may be unique to the STL units with the tig function) The plug is again a 20A type, but 20A does not cut it for either voltage.

    The 30A you mention is the same as the NEMA 50A plug on my larger stick and tig machines. These are rated 30 and then 50A. The problems is not finding a plug but that the actual receptacle that the existing cord plugs into, is limited to 20A. If I cut the cord I have many options including twist lock.

    I am starting to lean toward putting a 30A twist lock plug on the welder and wiring a 30A 230V twist lock outlet for the shop. I hate to cut the factory cord but then I can make an adapter, twist lock to 115V 20A or even 15A for the field. Since the welder is auto line, I guess this would give me the most options. I can also make a make a 30A twist lock "pig tail" that I can wire directly to a breaker in the panel on the job.

    It just seems that this situation cannot be unique to me and I was looking to see what solutions others may have come up with.

    Thanks,

    John

  4. #4
    Join Date
    Aug 2006
    Location
    N.C.
    Posts
    362

    Default

    90 Amps is the rated out put on 110v from the Maxstar 150S.....mine has done just fine on a shared breaker....if you look in the owners manual it will tell you to change the input cord to run on 220v....also the rating of the plug is on a full load not a duty cycle limited machine such as a welder.....so the 20 amp 110v plugs are for extended run times at 20 amps....just like the 30 and 50 amp 220v plugs and receptacles.....so running a 20 amp 110 plug at 28 amps for 3 min. isn't going to hurt it as the heat 28 amps creates / draws for 3 min. isn't as much as 20 amps for an hr....and as far as wiring the circuits in your garage you can save some $ by running one wire size smaller than you would for a "full load" circuit....IE a 30 amp 220v for a dryer you would want to run 10...well for a welder or other duty cycle limited machine you can run 12 and be just as safe.....you need to make sure you label the circuit as "welder only".....as far as plugging into the 220v line with a reg. 110v tool the same would apply, label it.....I have no worries as my adapter cord is locked in my shed and is on the cart for my Maxstar....as well as if it is out the welder is plug into it.
    Note:
    I am no expert with home electricity so the above is advice and should be used as such......if you talk to / with some elctricians they don't understand / know duty cycle and will laught at you if you tell them you are going to run a 30 amp 220v line with 12 ga. wire.....
    Good Luck,
    Mike
    George W. Bush was saving your butt whether you liked it or not!
    Fear is temporary, regret is forever
    HH210 with SG

  5. #5
    Join Date
    Sep 2005
    Location
    16919 Pole Rd. Brethren, MI 49619
    Posts
    4,376

    Default

    Personally I would have a dedicated 240V circuit in my garage to run these machines on, I like to use a 240V plug and recept while having an adapter to use for 120V portability.

  6. #6
    Join Date
    May 2007
    Posts
    539

    Default

    I agree with Sberry.

    My 375 likes 240 much better.

    The solution for me was to have 120 capability and 240 normal/typical operating power.

    Made up a adapter cable / extension cord for the rare 120 need.

    Wired workspace for 240.

  7. #7
    Join Date
    Dec 2007
    Posts
    157

    Default going 240...

    There is no doubt that the 220-240v circuits are better for the shop and that is what I have set up for my larger stick and mig machines. The issue was to try and maximize the output while not limiting the portability.

    I really wanted a dedictated outlet for each piece of equipment so everything can be plugged in and on at the same time if I wanted them to be. Of course I could not use everything simultaniously, but set up for a project would be flipping a few switches, rather than be digging through cords and plugging and unplugging...

    Well, I decided to go with the 30A 230v twist lock for the welder. I am making a patch cord for the twist lock to 115v 15A. This will let me plug the little welder in anywhere; of course the output will be limited based on the source.

    Warning for anyone else thinking of going this route: those twist lock plugs & receptacles are expensive...ouch.

    For the plasma, I wired a 20A 115v dedicated outlet. I already regret it and think I should replace it with a 20A 220v. I can make a similar patch cord with a 20A 220v to 15A 115v and maintain the same portability. I hesitated because the plasma is not auto line sensing and if I plug in the adapter and forget to switch the current it could be a problem. I dont think trying to run the plasma by mistake on the lower voltage would cause damage, but trying to run the 115v circuit on the 220v might. I am not sure what kind of overload protection is incorporated and would apply.

    Thanks for your input. Let me know if I am somehow missing the boat.

    John

  8. #8
    Join Date
    Apr 2007
    Location
    Ventura, California
    Posts
    102

    Default twist-lock pig-tails

    Quote Originally Posted by Handy560 View Post
    I am starting to lean toward putting a 30A twist lock plug on the welder and wiring a 30A 230V twist lock outlet for the shop. I hate to cut the factory cord but then I can make an adapter, twist lock to 115V 20A or even 15A for the field. Since the welder is auto line, I guess this would give me the most options. I can also make a make a 30A twist lock "pig tail" that I can wire directly to a breaker in the panel on the job.
    Howdy John!

    That's similar to what I did. My Dynasty just came with a power cable with bare ends so I put a male twist-lock on it, and a twist lock receptacle in the wall (replaced the electric dryer receptacle). If there is ever the need to run from another type of receptacle, I have some pig-tails made up to run 110 or 220 of different flavors. Having these pig-tails gives me portability.

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