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Another Noob 240V Question or two --

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  • mneblett
    started a topic Another Noob 240V Question or two --

    Another Noob 240V Question or two --

    Hi, all --

    New owner of a Miller 211. I have 240V in my garage with a 5-20r receptacle (currently used for my air compressor). I believe it necessarily is single-phase.

    The 211 and my 25-ft extension cord have 6-50p plug ends and a 6-50r receptacle on the cord.

    Two questions:

    1. After a lot of web surfing, I've concluded I can simply make up a cable with a male 5-20p end and a female 6-50r end, and plug straight into the 240V wall socket.

    Is this correct, or is there a better way to do this?

    2. I need to double-check my panel, but I believe I have 20 amp breakers feeding the 240V wall socket.

    Can/should I replace/upgrade the 20 amp breakers to 30 amp breakers?

    EDIT: If I do upgrade to 30 amp breakers, do I need to also upgrade the 5-20r wall socket?

    Thanks for the help!
    Mark
    Last edited by mneblett; 04-17-2013, 09:36 AM.

  • Sberry
    replied
    If you look at the user manual for any welder, it will specify the wire size and breaker that is to be used. That information is NOT just a recommendation to be followed or not as the user thinks best. Using a smaller breaker, in the event that you do not plan to use the welder at it's max capacity is OK, as long as the breaker does not exceed that allowed for the wire size.
    no one is disagreeing with this, quite the contrary. What it says is this,,, a 14 is allowed for use with this machine (it comes with 12 cord) while it is suffecient to power the unit without overheating it within its rated output it is not legal to use a 14 on a breaker larger than 30. It is legal to use a 12 up to a 50 depending on applied load,,, in this case a welder that has its own thermal and will let the smoke out before overheating the incoming. The only or main reason this machine has a 12 cord is to allow it for use on common 50 welder circuits.

    It comes with factory 50 cord and plug,,, nema says its got to be able to be plugged to 50.

    Using a smaller breaker, in the event that you do not plan to use the welder at it's max capacity is OK, as long as the breaker does not exceed that allowed for the wire size.
    you cant derate a derate,, a greedy synch is an example. it has a minimum wire, you cant use less than that and overbreaker a 6 because the wireisunderto begin with,,, in this case the breaker is protecting wire,,, with the 211 it isnt,, the applied load is the limiting factor,,, similar to light fixtures,,, lots of 16 in the world connected to 20 breakers, load limited by the fact its connected to Edison base fixture. Control wiring same way, wire has to be heavy enough to fault a 20 breaker.

    There is nothing wrong with an 8,,, good for any unit that comes 50a including most 250 class feeders. I use it in most of my shop, you can run a buzzer way beyond its rated output. But unless this is really discussed beyond simple many never realize how its all rated and works.
    Last edited by Sberry; 05-02-2013, 07:29 PM.

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  • zibby
    replied
    Originally posted by Broccoli1 View Post
    [ATTACH]32346[/ATTACH]

    If I'm reading it correctly 12g wire can only be protected by a 40amp CB max.
    Depends on the wire type, and then you have to derate it (voltage drop, temp, multi-wire etc)

    Leave a comment:


  • davido30093
    replied
    The main reason the breaker is there is as a disconnect and to provide for short circuit interruption.
    I understand that you are not going to give in on this point, but neither am I.

    The main reason for the breaker, any breaker/fuse, is to protect the wire, NOT the equipment. This is clearly stated in the NFPA NEC.

    There are other rules and recommendations regarding what size connector the equipment should have and what type of receptacle it should plug into. These are for the protection of the equipment. I understand that some welders come with "larger" plugs than their actual current draw and the NEC allows for larger breakers for a specific size wire to allow for the duty cycle of the welder, but these are not just "do it however you want" situations. There are very specific rules regarding wire size, breaker size, and welder duty cycles based on serious engineering calculations for the purpose of safety. Violation of these rules is not smart or clever, but is dangerous and, in most cases, illegal.

    If you look at the user manual for any welder, it will specify the wire size and breaker that is to be used. That information is NOT just a recommendation to be followed or not as the user thinks best. Using a smaller breaker, in the event that you do not plan to use the welder at it's max capacity is OK, as long as the breaker does not exceed that allowed for the wire size.

    After all the discussion about 12 gauge wire, I'm glad I went with 8!
    Me too!!

    Leave a comment:


  • mneblett
    replied
    Originally posted by BD1 View Post
    Congrats on your 211. Get a couple of fire extinguishers, a 5 gallon bucket with water, and have a garden hose connected if needed. You can also get those harbor freight welding blankets too. Starting a fire when it is not intended is not good. Wife may get upset. Those sparks have a way of find places to hide. Good luck.
    Thanks -- already on hand, and I'm not going to start burning anything until I have blankets. If I start a fire in the garage, her 1973 BMW R75/5 burns up -- and I won't survive the trauma!

    Originally posted by Sberry View Post
    For giggles look at the electric service guides for these macines. Miller doesnt reduce much confusion with theirs, they need a laymans guide with a mfg spec one step above code mins. Lincoln buzzers OM is worth looking at, they do not allow sub code installs, it sheds some light on some of this.
    After all the discussion about 12 gauge wire, I'm glad I went with 8!

    Leave a comment:


  • Sberry
    replied
    For giggles look at the electric service guides for these macines. Miller doesnt reduce much confusion with theirs, they need a laymans guide with a mfg spec one step above code mins. Lincoln buzzers OM is worth looking at, they do not allow sub code installs, it sheds some light on some of this.

    Leave a comment:


  • Sberry
    replied
    i have never seen one caused from a welder wiring and I have seen some shady setups. On a buzzer light wire can work but there is such a difference in drop between a 12 and a 10 it just works better and isn't a worry should someone haul azz and exceed the duty cycle. Something to consider is on a machine with a factory cord its likely a 12 (250a feeders come bigger) but 12 with a 50a plug. The main reason the breaker is there is as a disconnect and to provide for short circuit interruption. This is a circuit for a welder, the wire is protected by the theory that the machine will overheat before it cooks the wire,,, in the real world not so good, a buzzer will run fine wayyyyyyy beyond its rated output, that could cause a problem.

    Leave a comment:


  • davido30093
    replied
    When it comes down to it brother you should always have the greater rather than the lesser. If you dont you'll be poppin breakers left and right.
    And, if the breaker is too big for the wire size, you will be starting fires left and right.

    Leave a comment:


  • Missouripipewelder
    replied
    When it comes down to it brother you should always have the greater rather than the lesser. If you dont you'll be poppin breakers left and right.

    Leave a comment:


  • davido30093
    replied
    If I'm reading it correctly 12g wire can only be protected by a 40amp CB max.
    You are reading it correctly.

    Leave a comment:


  • Sberry
    replied
    Its at 50 depending on the method and type. A Stickmate or Linc buzzer can be 12, single circuit in pipe. No one thinks ita a great idea. It has to do with the machine, a 211 can use cable with 12, ideal for 2 machines in this class with only 1 breaker.

    This is why the 35 max brkr when used with 14 for the 211 type machines, use the minimum wire you have to reduce the ocpd, above that it can be up to 50A.

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  • Broccoli1
    replied
    Click image for larger version

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    If I'm reading it correctly 12g wire can only be protected by a 40amp CB max.

    Leave a comment:


  • BD1
    replied
    Congrats on your 211. Get a couple of fire extinguishers, a 5 gallon bucket with water, and have a garden hose connected if needed. You can also get those harbor freight welding blankets too. Starting a fire when it is not intended is not good. Wife may get upset. Those sparks have a way of find places to hide. Good luck.

    Leave a comment:


  • davido30093
    replied
    See NEC 630.11 (A) and (B) and 630.12 (A) and (B).

    Leave a comment:


  • Sberry
    replied
    You might be right and I might be wrong but show me where they wrote it?

    Leave a comment:

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