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  • kwired
    replied
    Originally posted by hbiss View Post
    And industrial/automated welders wouldn't be cord and plug connected so 630.12 could be applied.

    Is this a "shop welder"? It comes with a 50A plug. Is there anything in the instructions that say to use a 60A breaker? Has it been used and found to trip a 50A breaker? Why are we debating this???

    -Hal
    I agree, if a 60 amp breaker were necessary chances are it would come with a 60 amp cord cap.

    Leave a comment:


  • hbiss
    replied
    Originally posted by kwired View Post

    For typical "shop welder" for general maintenance, repairs, etc. yes, duty cycle is often low, machine often will protect itself with a thermal overload even if you don't have the recommended branch circuit device installed. Industrial/automated welders is where you might be more likely run into continuous duty and issues with tripping supply breakers if load is near the breaker rating.
    And industrial/automated welders wouldn't be cord and plug connected so 630.12 could be applied.

    Is this a "shop welder"? It comes with a 50A plug. Is there anything in the instructions that say to use a 60A breaker? Has it been used and found to trip a 50A breaker? Why are we debating this???

    -Hal

    Leave a comment:


  • kwired
    replied
    Originally posted by wwhitney View Post
    All correct. And the fact that you can use a 50 amp conductor at 50 amps continuously on a 50 amp 100% rated breaker shows that the conductor rating is itself a continuous rating.

    For non-100% rated breakers, it is a limitation of the breaker that requires oversizing (125%) the breaker for a continuous load. Then of course the conductor needs to be oversized (125%) so that it is adequately protected by the oversized breaker.

    Cheers, Wayne
    The major thing that is different with 100 vs non 100% breaker rating is terminations. Non 100% breakers sink some heat into the terminal/conductor, therefore the issues are mostly with heat in the terminations. A 100% breaker may be electronic and not create as much internal heating or have other methods of managing such heat. Most such breakers are stand alone and in individual enclosure and not something you find in a general branch circuit/feeder panelboard.

    Leave a comment:


  • wwhitney
    replied
    Originally posted by kwired View Post
    If you have a non continuous load you can run a 50 amp load on a 50 amp conductor on a 50 amp breaker. If that 50 amp load is continuous, you now need 125% added to minimum conductor ampacity as well as overcurrent protection, unless you have a 100% rated device.
    All correct. And the fact that you can use a 50 amp conductor at 50 amps continuously on a 50 amp 100% rated breaker shows that the conductor rating is itself a continuous rating.

    For non-100% rated breakers, it is a limitation of the breaker that requires oversizing (125%) the breaker for a continuous load. Then of course the conductor needs to be oversized (125%) so that it is adequately protected by the oversized breaker.

    Cheers, Wayne

    Leave a comment:


  • kwired
    replied
    Originally posted by wwhitney View Post
    Apparently a regular thermal magnetic breaker could start nuisance tripping if used at over 80% of its rating continuously, depending on ambient temperature, loading of other breakers in the panel, etc. So for a continuous load on a regular breaker, the breaker needs to be upsized, which then causes the conductors to be upsized.
    If you have a non continuous load you can run a 50 amp load on a 50 amp conductor on a 50 amp breaker. If that 50 amp load is continuous, you now need 125% added to minimum conductor ampacity as well as overcurrent protection, unless you have a 100% rated device. Loads with a temporary high starting current may need higher overcurrent protection just to prevent tripping on startup.

    Originally posted by sameguy View Post
    Duty cycle of welder? 20% 30%. Type of welder?
    When was the last time the welder section was reviewed, 1914?
    For typical "shop welder" for general maintence, repairs, etc. yes, duty cycle is often low, machine often will protect itself with a thermal overload even if you don't have the recommended branch circuit device installed. Industrial/automated welders is where you might be more likely run into continuous duty and issues with tripping supply breakers if load is near the breaker rating.

    Leave a comment:


  • sameguy
    replied
    Duty cycle of welder? 20% 30%. Type of welder?
    When was the last time the welder section was reviewed, 1914?

    Leave a comment:


  • hbiss
    replied
    I agree with those who say the OCP can't be more than the rating of the receptacle. 630.12 would apply to hard wired machines.

    But let's get back to the original question. I assume the welder has a 50A plug and that's why you need a 50A receptacle. What makes you think you need a 60A breaker?

    -Hal

    Leave a comment:


  • wwhitney
    replied
    Originally posted by Jraef View Post
    Breakers are not "80% rated", it's a common misconception. Breakers are not supposed to be USED at more than 80% of their rating, because CONDUCTORS are supposed to be sized at 125% of the continuous circuit load.
    I'm going to have to disagree with that. Conductors are "100% rated", since with a 100% rated breaker, the conductors can be sized at 100% for continuous loads, not 125%. It is the breakers that are the weak link. Apparently a regular thermal magnetic breaker could start nuisance tripping if used at over 80% of its rating continuously, depending on ambient temperature, loading of other breakers in the panel, etc. So for a continuous load on a regular breaker, the breaker needs to be upsized, which then causes the conductors to be upsized.

    That's the physics of it as I understand it. The code wording may suggest otherwise, but that's just a choice of how to write the rules.

    Cheers, Wayne

    Leave a comment:


  • david luchini
    replied
    Originally posted by turtlepokerman View Post
    Article 630.12 only defines the overcurrent protection for the welder and the supply conductors, but does not state the overcurrent requirements for the receptacle.
    See 210.21(B)(1) Exc No 2

    Leave a comment:


  • Jraef
    replied
    ...I don't think the receptacle would ever see the a value over 50A as the breaker is 80% rated to 48A.
    So you seem to believe that a 60A breaker will trip at less than 60A, that is absolutely untrue. In fact it will not likely trip at 60A for a very long time.

    Breakers are not "80% rated", it's a common misconception. Breakers are not supposed to be USED at more than 80% of their rating, because CONDUCTORS are supposed to be sized at 125% of the continuous circuit load. So since the primary job of the breaker is to protect the conductors, and the conductors should not see more than 80% of their rating (80% load is the inverse of 125% over sizing), the breaker never sees more than 80% loading, so when they put them in a panelboard, they are not expecting any breaker in that panel to reject the heat of more than 80% of its rated load. But all breakers are tested at 100% load and that is what the trip setting is based on. The thing that makes a "100% rated breaker" different is that you cannot use one unless you are connecting to bus bars, or you are following other strict rules on conductor selection, AND, the breaker is all by itself, no other breakers around it.

    Leave a comment:


  • jap
    replied
    Originally posted by turtlepokerman View Post
    Dennis,

    Article 630.12 only defines the overcurrent protection for the welder and the supply conductors, but does not state the overcurrent requirements for the receptacle. If I have a #6 wire feeding a a 50A receptacle fed from a 60A Breaker, [COLOR="#FF0000"][/COLOR]I don't think the receptacle would ever see the a value over 50A as the breaker is 80% rated to 48A.

    Comparing this situation to a feeder cable where I use can use the 240.4(B) rule to feed a #6 (60C) conductor with a 60A Breaker as 55A is not a standard size. I don't know if I can do this for a 50A receptacle as a 50A breaker is a standard breaker rating.

    I'd have to disagree.

    There is nothing that would limit the receptacle from ever seeing a value more than 50 amps.

    It's more than likely the circuit will see more than 50 amps more times than not.

    There is a very limited number of receptacles that are allowed to be fed by an OCPD higher than their rated amperage.

    JAP>

    Leave a comment:


  • Dennis Alwon
    replied
    I get you. I am not sure of the answer but I believe that is allowed especially since your conductors are not usually sized for the breaker

    Leave a comment:


  • turtlepokerman
    replied
    Dennis,

    Article 630.12 only defines the overcurrent protection for the welder and the supply conductors, but does not state the overcurrent requirements for the receptacle. If I have a #6 wire feeding a a 50A receptacle fed from a 60A Breaker, I don't think the receptacle would ever see the a value over 50A as the breaker is 80% rated to 48A.

    Comparing this situation to a feeder cable where I use can use the 240.4(B) rule to feed a #6 (60C) conductor with a 60A Breaker as 55A is not a standard size. I don't know if I can do this for a 50A receptacle as a 50A breaker is a standard breaker rating.

    Leave a comment:


  • Dennis Alwon
    replied
    You need to look at art. 630. Hope this helps

    630.12 Overcurrent Protection. Overcurrent protection for
    arc welders shall be as provided in 630.12(A) and (B). Where
    the values as determined by this section do not correspond to
    the standard ampere ratings provided in 240.6 or where the
    rating or setting specified results in unnecessary opening of the
    overcurrent device, the next higher standard rating or setting
    shall be permitted.
    (A) For Welders. Each welder shall have overcurrent protection
    rated or set at not more than 200 percent of I 1max. Alternatively,
    if the I 1max is not given, the overcurrent protection shall
    be rated or set at not more than 200 percent of the rated
    primary current of the welder.
    An overcurrent device shall not be required for a welder that
    has supply conductors protected by an overcurrent device rated
    or set at not more than 200 percent of I 1max or at the rated
    primary current of the welder.
    If the supply conductors for a welder are protected by an
    overcurrent device rated or set at not more than 200 percent of
    I 1max or at the rated primary current of the welder, a separate
    overcurrent device shall not be required.
    (B) For Conductors. Conductors that supply one or more
    welders shall be protected by an overcurrent device rated or set
    at not more than 200 percent of the conductor ampacity.

    Leave a comment:


  • turtlepokerman
    started a topic Receptacle Overcurrent Rating

    Receptacle Overcurrent Rating

    Greetings,

    If I have a 50A Welding Receptacle am I allowed to feed it from a 60A Breaker? The receptacle is solely designed to be used for a cord-and-plug connected welding receptacle. The wording in Article 210.21(B)(1) is slightly vague when it comes to overcurrent protection. Article 210.20(D) states that the overcurrent protection is dependent upon 210.21.

    I believe the purpose of the 210.21(B)(1) is to prevent a receptacle from melting due to an overload condition. However if an upstream breaker is 80% rated, I don't know how this would be possible. Thoughts?

    All help is appreciated!
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