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Thread: SCCR NEC409

  1. #11
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    The scope of UL508a specifically excludes things that are not part of the control panel.


    1.4 An industrial control panel does not include an evaluation of the controlled equipment such as motors,
    heaters, lighting, and other loads connected to power circuits. Unless specifically noted on the wiring
    diagram of the industrial control panel, an industrial control panel does not include equipment mounted
    remotely from the panel and connected via a wiring systems or equipment field installed on or within the
    industrial control panel.
    There are times you might want to make it part of your control panel, such as if you have a disconnecting means that is separate but is required by the standard.
    Bob

  2. #12
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    If it were me, and I am responsible for the entire assembly, I would rebuild the hoist panel and make it compatible with a reasonable AFC. Its not really that difficult if you know what to do. I can see you might not want to change any control systems and maybe drives if there are any in there, but if you look up the drives or starters, chances are that they can have a higher SCCR when used in conjunction with a specific protection device. So all you need do is use that specific protective device, not the cheapest piece of junk the OEM could find. If they used some bizarre piece of equipment that has no SCCR rating available, it might be worth investigating changing it out for something that does. Control components don't count, only devices in the power circuits.
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  3. #13
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    Quote Originally Posted by petersonra View Post
    The scope of UL508a specifically excludes things that are not part of the control panel.




    There are times you might want to make it part of your control panel, such as if you have a disconnecting means that is separate but is required by the standard.
    Thank You !

    Quote Originally Posted by Jraef View Post
    If it were me, and I am responsible for the entire assembly, I would rebuild the hoist panel and make it compatible with a reasonable AFC. Its not really that difficult if you know what to do. I can see you might not want to change any control systems and maybe drives if there are any in there, but if you look up the drives or starters, chances are that they can have a higher SCCR when used in conjunction with a specific protection device. So all you need do is use that specific protective device, not the cheapest piece of junk the OEM could find. If they used some bizarre piece of equipment that has no SCCR rating available, it might be worth investigating changing it out for something that does. Control components don't count, only devices in the power circuits.
    Exactly,
    I should mention this hoist control panel (sub) Contains the starters and OL's for the hoist motor. it'll wait until the hoist gets here and look at the components and see how I can best marry them to my system. I don't want to just default my panel to 5ka (As the hoist company seems to have done!)
    then I can evaluate what I need to do to maintain a higher SCCR.

    Great discussion guys ! I Thank you for all the great replies, there is a lot of talent and knowledge on this forum and it is always very helpful..

  4. #14
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    Something worth noting that I just read yesterday: in the 2017 NEC changes, they have apparently added a rule that a "machine" that has multiple control panels on it must now be labeled with an overall SCCR for the system as a whole. So that becomes pertinent to your exact situation. If you have 5 different panels on the machine and just one of them is defaulted to 5kA, the label for the entire machine must now say 5kA even if the other 4 are 65kA. So it's becoming even more important for OEMs to address this up front and for users to specify what kind of SCCR they require for anything they buy that has controls (for line power) on it.

    Whether or not your state has adopted the 2017 code yet or not is relevant, at least for now. Here in CA we just recently finally adopted the 2014 code, so it's not going to hit here for a while.
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  5. #15
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    I haven't really checked this out, but it looks like a good resource.

    http://lvpinfo.com/319/Copied/ea83fb...6-8cf1ff463d10

    To make improving your control panel design easier, our experts have designed this toolkit take the work out of SCCR calculations so you can stay focused on the bigger picture. Click on the link in our Resource Center below to get your FREE pocket-sized slide rule to assist you with on-the-spot calculations. Our 3-step training module walks you through real-life examples of calculations. Our white paper gives an overview of the process. Be sure to stay up to date with the latest solutions and technology by subscribing to our newsletter. In addition, the published system ratings of tested and certified motor controllers are listed on the UL website, providing you another information time-saver to make control panel design even simpler.
    The more they overthink the plumbing, the easier it is to stop up the drain

  6. #16
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    Quote Originally Posted by Jraef View Post
    Something worth noting that I just read yesterday: in the 2017 NEC changes, they have apparently added a rule that a "machine" that has multiple control panels on it must now be labeled with an overall SCCR for the system as a whole. So that becomes pertinent to your exact situation. If you have 5 different panels on the machine and just one of them is defaulted to 5kA, the label for the entire machine must now say 5kA even if the other 4 are 65kA. So it's becoming even more important for OEMs to address this up front and for users to specify what kind of SCCR they require for anything they buy that has controls (for line power) on it.

    Whether or not your state has adopted the 2017 code yet or not is relevant, at least for now. Here in CA we just recently finally adopted the 2014 code, so it's not going to hit here for a while.
    I don't see that in article 409. Where is this new rule to be found?
    Bob

  7. #17
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    Quote Originally Posted by petersonra View Post
    I don't see that in article 409. Where is this new rule to be found?
    I read it in the course of looking for something else, I can't find it now. I just remember seeing it and that it pertained to the 2017 NEC, but since we just recently accepted 2014, I didn't pay a lot of attention. I'll have to go through my browser history I guess, but I tend to get lost in it again when I do that....
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  8. #18
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    The overcurrent fuses FU1, FU2, FU3 you have selected are current limiting type. You can take the available fault current and find out from the fuse mfg how much "peak let through current" those fuses will allow. Read this from Littelfuse, it provides information on improving SCCR with current limiting fuses. I used to design panels for a 508 shop and we used this method time and time again when certain distribution blocks didn't have combination ratings with the circuit breakers.

    I have a hard time believing that the available fault current at the hoist is higher than 5kAIC. What size conductors (#10 AWG) and what length are feeding the hoist? What is the available fault current at the 7549 bus? How much fault current is "let through" when the 7549 panel is subjected to 65 KAIC, and how much of this reaches the hoist considering the impedance of the conductors connecting the hoist to 7549?

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