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  • How many amps needed for MM251?

    I'm currently looking to purchase a MM251. I have been doing some research on how many amps I need to hook this welder up in my garage. From the Tech Spec. sheet it looks like a 50amp Circuit Breaker with 6-3 gauge wire will be good Since, if I'm reading it correctly that at 200v it pulls 48 amps, which would be the maximum amps the MM251 would draw.

    From the Breaker Box to the receptacle will be about 25-30 feet. I spoke with a Electrician and he seems to think this will be fine. I just found this forum and would like to get the opinion of others.. I did do some searching to see if someone did post this question, but maily it seemed to be for the MM201

    Thanks,

    Bronco STD

  • #2
    Power Service

    I have just wired up a kitchen range receptacle in several shops for the 220..worked fine..used 60 amp double pole breaker.. 6-3 wire size on 60 amp..you can probably use 50 amp if you like and go to 8-3 wire size..Check the National electric code on this and there is a chart to tell you what size wire goes with what breaker..don't have the chart on my desk....While you are wiring it is helpful to also put in a 20 amp dedicated circuit for grinders..drill..saws and things of that nature..

    While you are at this you might wish to look into an extension cord so you can have some more latitude to move around the shop..That cord would be either 8-3 or 6-3 sjt wire..Match the wire size from the breaker..

    Havign a good solid power source makes thigs go better so you are on the right track here..

    makes life a bit easier..

    Take care

    Grampa
    Grampa has done so much with so little now I do everything with nothing..;>)

    Comment


    • #3
      The 50 amp should be enough but a suggestion, use a slow blow breaker also known as a compressor breaker since they start under pressure the have high amp start up then drop to normal amperage. The 8ga 3wire should be sufficient for power carrying, If you get an extension make sure it has a thick insulation for the occasional nick or cut, I have a 4/3 and 6/3 extension both are Industrial grade SO cable, it is better to go bigger but don't go crazy remember you still have carry it and move it around. The 4/3 is 100' long and weighs over 100pounds.

      Comment


      • #4
        Bronco
        according to the manual it draws 42amps at 230vac and that you can run up to 127ft of 8/3 with a 60amp regular breaker or a 50amp time delay... all the info is on pg 19 of the pdf manual... have enclosed the link...

        http://www.millerwelds.com/om/o1326p_mil.pdf

        hope this helps
        Heiti
        .

        *******************************************
        The more you know, The better you know, How little you know

        “The bitterness of poor quality remains long after the sweetness of low price is forgotten”

        Buy the best tools you can afford.. Learn to use them to the best of your ability.. and take care of them...

        My Blue Stuff:
        Dynasty 350DX Tigrunner
        Dynasty 200DX
        Millermatic 350P w/25ft Alumapro & 30A
        Millermatic 200

        TONS of Non-Blue Equip, plus CNC Mill, Lathes & a Plasmacam w/ PowerMax-1000

        Comment


        • #5
          amps

          Thanks for the information on the Users Guide. I ran the 6-3 gauge wire last night about 25ft of it from the box to the receptacle. I bought a 50amp breaker, thinking that would be enough, but I'll run and get a 60amp before everything is hooked up. I don't think I will be using that many amps to it's fullest potential anyway, but just to be on safe side.

          Thanks for the feedback

          Bronco STD

          Comment


          • #6
            Ok guys, correct me if I am wrong.

            Isn't a breaker considered a re-settable fuse??

            If the manufacture reccomends to use a 50amp breaker why would you want a larger one on that circuit if you are dedicating that circuit for the welder?

            For instance, for the MM251 it was stated the a 50amp breaker should be used.

            Meaning the the machine should operate properly on this 50 amp circuit without tripping the breaker.

            So if one were to use a 60 amp breaker on equipment that should "trip" a 50 amp breaker if a problem were to arise; wouldn't that cause for an additional 10 amps of malfunction or catastrophy to trip the 60 amp breaker?

            Resulting in unneccessary damage and stress to the machinery and circuits involved.

            Comment


            • #7
              I just realized that there are some great posts on the importance of electrical safety in the "Welder Wiring" Thread.

              Check them out.

              Comment


              • #8
                Dieseladam: you are correct but in the 50amp example it would need to be a compressor rated breaker since they start under load the use more then the rated for startup then taper to the rated usage AKA "slow blow breakers" the 60 amp would allow for the higher startup amperage. I hope this helps

                Comment


                • #9
                  Guys
                  the the Welder Wiring Safety thread was started because of the type of Generalized and usually somewhat scary advice that Grampa gave earlier in this thread... as a matter of fact... all of my what not to do examples were from his "ADVICE" .....(wish he would talk less and think more) the Miller manuals do specify the size and type of breaker as well as wire size....
                  hope this helps
                  Heiti
                  .

                  *******************************************
                  The more you know, The better you know, How little you know

                  “The bitterness of poor quality remains long after the sweetness of low price is forgotten”

                  Buy the best tools you can afford.. Learn to use them to the best of your ability.. and take care of them...

                  My Blue Stuff:
                  Dynasty 350DX Tigrunner
                  Dynasty 200DX
                  Millermatic 350P w/25ft Alumapro & 30A
                  Millermatic 200

                  TONS of Non-Blue Equip, plus CNC Mill, Lathes & a Plasmacam w/ PowerMax-1000

                  Comment


                  • #10
                    So from the manual I should be running a 50amp instead of a 60amp breaker under 230v. I have a siemens breaker box, and what was currently just put in there is a 60 amp double pole breaker. The manual is a bit confusing since it refers to "time delay" and "normal operating". I think I'm making this harder then it is. I have not used the welder as of yet, since I wanted to make sure I have the correct breaker installed.

                    Thanks,

                    Bronco STD

                    Comment


                    • #11
                      Bronco STD
                      if the 60amp breaker that you have installed is of the standard fast-trip variety... then you have the right one... the extra amperage above your "working" amperage needs is there to compensate for the starting or turn on surge when the transformer initially gets energized.. this is why it is sometimes called "inrush current" .... the 50amp that they specify is a time delay that compensates for that.... does that make sense... if not i will try to explain further..(the breaker types are marked on them in their model number.. if you have doubts.. will try and help decode them for you)
                      hope this helps
                      Heiti
                      .

                      *******************************************
                      The more you know, The better you know, How little you know

                      “The bitterness of poor quality remains long after the sweetness of low price is forgotten”

                      Buy the best tools you can afford.. Learn to use them to the best of your ability.. and take care of them...

                      My Blue Stuff:
                      Dynasty 350DX Tigrunner
                      Dynasty 200DX
                      Millermatic 350P w/25ft Alumapro & 30A
                      Millermatic 200

                      TONS of Non-Blue Equip, plus CNC Mill, Lathes & a Plasmacam w/ PowerMax-1000

                      Comment


                      • #12
                        I Started Something!!!

                        If I posted something up here and scared the **** out of everybody and now people are really paying attention to electrical safety and proper wiring then it is a good thing in my mind..

                        I know that my expertise and experience is in question here..But ya know I am a big boy and can take the heat..

                        Now I have yet to see anyone address panel loads..How about distance of wire runs? how it affects voltage drop?..what about service disconnects on your equipment..?? calculating panel loads? Proper securing of wires to boxes and studs? Do you really know all that sort of thing..If you are not sure about all this get Sparky over there..Heavens maybe you guys can trade out some work or something to tkae care of Sparky..

                        Guys it is real easy to pop in a breaker..pull some wire and install an outlet

                        Do you know all that stuff..Gotta know it to do it right..Just like you gotta know and practice your welding to do that right..


                        What is seen often in the field is that some guy reads all the manuals..gets the specified size of breaker..the correct wire according to the book..the right specified outlet and hooks up his welder..

                        Then he gets a plasma cutter..same deal..does it all correct according to the book..

                        Adds a large verticle compressor..same thing..reads his book..and does it that way..

                        Now we get some nice lighting..add some utility circuits for the grinders and drill motors..

                        Now to a lay person this shop looks real neat..everything nice and tidy all that..

                        All of this looks just fine..

                        Now it is winter..buds come over to help.They are doing some welding..compressor is going..some space heaters are in operation..and the wives are in making a meal..the washer and dryer is going..all the lites are on and the kids watching TV..

                        Now the panel is way overloaded..the service panel melts down and causes a fire..Fire Marshall shows up and writes up "Point of ignition the electrical panel"

                        The Insurance adjuster then shows up with a copy of the Fire Marshall's report..looks at the wiring setup and asks.."do you have copies of the permits and inspections on this wiring" .."Who did the work'? She is not about to pay an insurance claim on someone's bootleg wiring deal..No matter that it was all done according to "instructions and code"..In fact when she leaves your house she is on the way to the local building dept to pull the electrical permit records on the deal..to prove that this was some kind of bootleg deal..

                        Now you are standing there with mud on your face wondering how and where to get the money to fix your house...fighting with the Insurance company..

                        See one can "do it all right" and still get in a lot of trouble..!!!

                        So if you would like to cover yourself..Call Sparky the electrician..have him do it and if you do it your self..take a permit and let the inspector do his thing..

                        Nuff said on this one

                        Grampa
                        Grampa has done so much with so little now I do everything with nothing..;>)

                        Comment


                        • #13
                          Thanks for the input.. I will check when I get home what the breaker says. It sounds like I have the correct one. I didn't specify to the parts man that I needed a time delay breaker. So I'm assuming he gave me the standard fast trip kind for about 10 bucks. If it were the time delay, then I bet that breaker would cost more?

                          Bronco STD

                          Comment


                          • #14
                            GRAMPA PLEASE!!!!!!!!!!!!!!!!

                            Grampa
                            PLEASE!!!! havent you muddied the water enough with your ERRONIOUS folksy stuff!!!! The welder Wiring Safety Thread was started in Direct response to your DANGEROUS advice.... and when confronted..you twisted it around and then you acted like you had started the darned thing..... you may be trying to be helpful ... or you may just get your jollies from hearing yourself talk... i do not know which
                            but... you sure scare the heck out of me...
                            Heiti
                            .

                            *******************************************
                            The more you know, The better you know, How little you know

                            “The bitterness of poor quality remains long after the sweetness of low price is forgotten”

                            Buy the best tools you can afford.. Learn to use them to the best of your ability.. and take care of them...

                            My Blue Stuff:
                            Dynasty 350DX Tigrunner
                            Dynasty 200DX
                            Millermatic 350P w/25ft Alumapro & 30A
                            Millermatic 200

                            TONS of Non-Blue Equip, plus CNC Mill, Lathes & a Plasmacam w/ PowerMax-1000

                            Comment


                            • #15
                              Wow that would be a scary scenario. But I do see some flaws in it.

                              Let me elaborate.

                              For instance, I am in the process of upgrading the service to my house.
                              It is currently on 100 amp service.

                              From the meter can I have the main breaker which has a 100 amp breaker inside it.

                              From the main breaker can it goes to my breaker panel which is rated at 125 amps.

                              The new service is going to be underground @200 amps.I have to install a 200 amp main breaker off of the new meter can. IT is then wired to my new breaker box inside the house which is rated at 225 amps.

                              Mind you I have already had load calculations done because I am also adding an addition to the house. The load calculations are required.

                              In order to melt the breaker box (distribution inside the house) I would probably have to pull a **** of alot more than 200 amps (the size of the breaker AFTER the meter can) (but before the breaker can inside) make sence?

                              So in theroy it is probably impossible to "pull" more from your breaker box INSIDE the house without tripping the main first.

                              Now, Let's throw a little twist to all of this !!!!!

                              Go ahead and open the breaker panel inside YOUR house.

                              Write down the ratings of all the breakers in the panel.

                              Then add em up !


                              AHHHHHHHHH We're all guunna die!!!!!!!!!!!!!!!!!!

                              and who the heck is Sparky anyway?

                              Comment

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