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  1. Thread: VFD Wire Size

    by Jraef
    Replies
    24$$
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    414

    In my experience that happens quite often...

    In my experience that happens quite often actually. The issue is one of original intent vs the 2nd or 3rd or 4th guy down the road coming across the drive rating and getting pressure to get more out...
  2. Thread: VFD Wire Size

    by Jraef
    Replies
    24$$
    Views
    414

    430.122 requires that the line side conductors...

    430.122 requires that the line side conductors feeding power conversion equipment (such as a VFD) are to be sized at 125% of the rated input current of the device. This is not interpretable based on...
  3. Replies
    7$$
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    188

    If you are looking at a mag trip setting of 120A,...

    If you are looking at a mag trip setting of 120A, that will correspond to a motor FLC of between 11A (1100% trip) and 15A (800% trip) for a normal motor, maybe as low as 7A (1700% trip) if it is an...
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    2$$
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    99

    The IR of the protective device is a factor in...

    The IR of the protective device is a factor in determining the SCCR but any value higher than the SCCR is irrelevant, so there is no requirement to show it, in fact it can be confusing to those not...
  5. Replies
    21$$
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    570

    Someone should probably make this issue a...

    Someone should probably make this issue a "sticky", it comes up a lot here.

    Circuit breakers that plug into or bolt directly onto a load center or panelboard bus bar must be specifically listed in...
  6. Replies
    21$$
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    570

    If necessary, your local Siemens office can give...

    If necessary, your local Siemens office can give you a letter certifying that Siemens and Murray breakers are one and the same. The ONLY difference is the little piece of paper with the name on it....
  7. Replies
    6$$
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    283

    How would the tap rule apply here? Don’t...

    How would the tap rule apply here?

    Don’t overlook the heat load and work space clearance issue in that room.
  8. Replies
    6$$
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    337

    For a 40’ run already pulled in steel conduit, I...

    For a 40’ run already pulled in steel conduit, I wouldn’t redo it.

    But yes, any XHHW would be better than THHN. I generally recommend the 1000V rated just because there is no difference in price...
  9. I think you are over interpreting that 30"...

    I think you are over interpreting that 30" minimum width issue in thinking that EACH device must have 30", ergo 15" from center to either side. The rule is to avoid having someone cram stuff into a...
  10. Replies
    9$$
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    299

    Oh wait, sorry, I get it now. You BELIEVE you are...

    Oh wait, sorry, I get it now. You BELIEVE you are going to find an old starter with two OL heaters inside, which will stop you from finishing the job because you can't reconnect to it, so you want to...
  11. Replies
    9$$
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    299

    How can you connect a new motor to this starter...

    How can you connect a new motor to this starter without opening it?

    Proving what to them, that it is no longer legal to use an OL relay with heaters on only two legs? That's in the NEC. They are...
  12. Replies
    11$$
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    399

    If you are using fine stranded cable such as...

    If you are using fine stranded cable such as DLO/RHH, there are probably no mechanical lugs that you can use for them. The lugs must specifically say on them that they are good for "Class K...
  13. Replies
    9$$
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    299

    Why worry about it? Just buy a new 3 phase...

    Why worry about it? Just buy a new 3 phase separately mounted OL relay from your favorite source and wire it in. Nelson was bought by General Signal, who was then bought by OZ Gedney decades ago, who...
  14. Replies
    6$$
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    337

    Like an assisted living facility, there are a lot...

    Like an assisted living facility, there are a lot of “depends” involved. It depends on how the wire is run, it depends on what carrier frequency you use, it depends on the quality of the VFD, etc...
  15. That seems misleading to me, I wonder if there is...

    That seems misleading to me, I wonder if there is some sort of context missing. All the VFD should care about is the FLA of the motor.

    I’m thinking this relates to a common “trick” used when you...
  16. When I was in Washington State, I could have...

    When I was in Washington State, I could have attained a PE with my BSEET, but I needed 3 recommendations from existing PEs and I couldn’t muster more than one, I wasn’t working for a firm that had...
  17. What you are saying makes no sense, you have some...

    What you are saying makes no sense, you have some sort of misconception taking place here.

    There is no “conversion” to take place, a motor is either wound as delta or wye inside, but that makes...
  18. Looks as though the motor nameplate Amps is 1.53...

    Looks as though the motor nameplate Amps is 1.53 @400V, so a setting of 1.3A would nuisance trip. That then may lead to operators constantly resetting it, or worst case someone figured out how to...
  19. Replies
    17$$
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    491

    Exactly, it's an older concept still used in some...

    Exactly, it's an older concept still used in some industries. I call it the "Damn the torpedoes, full speed ahead!" philosophy. In an industrial facility if you have an ungrounded delta* system and...
  20. Replies
    23$$
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    603

    The only potential issue I foresee is when...

    The only potential issue I foresee is when someone wants to work on only one of those circuits but is forced to kill all three. I don’t know what they are for, but think of a work shed and one...
  21. Replies
    16$$
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    548

    All of those questions are typically aspects of...

    All of those questions are typically aspects of the programming choices available. The NEC is not involved in those types of details, unless the “Full On at power fail” is being considered emergency...
  22. Replies
    28$$
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    681

    I would be surprised if a 480V 3 phase service...

    I would be surprised if a 480V 3 phase service did not come with a Demand Meter. That would be very useful information because in order for them to charge a “peak demand” penalty, they now (with...
  23. Replies
    28$$
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    681

    If this is a commercial or industrial customer,...

    If this is a commercial or industrial customer, the utility may have a kW demand meter, which will give them the peak demand in kW, which can be used to determine worst case. But because kWh has a...
  24. That said, I've seen where the UTILITY owns the...

    That said, I've seen where the UTILITY owns the disconnect because it is AHEAD of the meter, and they use an non-fused disconnect. I believe this has been discussed in here before. Utilities don't...
  25. Yes, and that is easier to find for sure.

    Yes, and that is easier to find for sure.
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