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  1. Replies
    2$$
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    54

    No. 240V is the standard "Distribution Voltage"...

    No. 240V is the standard "Distribution Voltage" that utilities give us, 230V is the "Utilization Voltage" that equipment manufacturers build to, expecting that there will be some voltage drop between...
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    1$$
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    Back panels are made thicker than side walls so...

    Back panels are made thicker than side walls so that they can hold a minimum of 2 threads when drilled and tapped, which effectively eliminates sheet metal screws. As I recall the 2 thread minimum is...
  3. You can generalize that the motor current will...

    You can generalize that the motor current will increase by the same ratio of the voltage differential, so 10% is a good rule of thumb. But success really does depend on the application.

    A motor...
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    What “cable” are you talking about? You prefaced...

    What “cable” are you talking about? You prefaced this talking about the FEEDER, which by definition would be the wires going INTO the control panel. Those would be field wiring and must comply with...
  5. Thread: Fire pump

    by Jraef
    Replies
    5$$
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    145

    Even if so, I'm thinking that said transformer...

    Even if so, I'm thinking that said transformer would be required to be capable of delivering LOCKED ROTOR CURRENT indefinitely, meaning it will have to be 6x larger than normal. It would probably be...
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    The only time I have seen restrictions like that...

    The only time I have seen restrictions like that they were self imposed, meaning it was an INTERNAL corporate policy. I worked for a while with a contractor that did soft starter retrofits of MV...
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    6$$
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    There's the source of your dilemma... this...

    There's the source of your dilemma... this statement is incorrect with respect to the FEEDER. The feeder conductors must be sized per the NEC, not UL508A and thus at 125% of the load. The INTERNAL...
  8. There are no UL standards for Arc Resistance. It...

    There are no UL standards for Arc Resistance. It is covered by ANSI
    ANSI/IEEE C37.20.7 defines switchgear arc resistance in two basic categories:

    ANSI type 1
    Arc resistance from the...
  9. Different issues. An Arc Flash Suit protects you...

    Different issues. An Arc Flash Suit protects you from being burned. What I mean by "no rating" is that if there is an arc BLAST inside of the equipment, a cover blowing open can become shrapnel and...
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    11$$
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    There used to be some battery operated retrofit...

    There used to be some battery operated retrofit ones that I saw a year ago or so that took 2 C batteries, but I couldn't find them again, company may have gone bust... If I can remember the name,...
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    Jim, With a lack of further details, we can only...

    Jim,
    With a lack of further details, we can only make suggestions based on assumptions:

    ASSuming that the motors run 24/7, then you will need a 48hr timer that has a "Form C" contact (Common,...
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    11$$
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    Hey, she already over paid for a system that uses...

    Hey, she already over paid for a system that uses two separate ducts for heating / AC, so she might be willing to pay for the motorized VAV boxes...
  13. Thread: VFD noise

    by Jraef
    Replies
    2$$
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    140

    How old is the drive? Cooling fans are usually...

    How old is the drive? Cooling fans are usually the first thing to go bad, but their failure then precipitates other failures, so the only thing you see is the collateral damage that happens AFTER the...
  14. If the conductors feeding the power supply line...

    If the conductors feeding the power supply line terminals do not exit the panel, they fall under "tap rules" (at least here in North America).

    Now that said; "internal non-replaceable fuses"?...
  15. If you were to need a disconnect within sight of...

    If you were to need a disconnect within sight of a disconnect, where does it stop? What if you have to work on the in-sight disconnect? You would have a continuous string of disconnects in...
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    6$$
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    457

    But no, “rain right” does not mean “watertight”. ...

    But no, “rain right” does not mean “watertight”. NEMA / UL Type 4 means hose down proof, defined as able to resist 100GPM from a 1” nozzle (roughly 60 PSI) aimed at any surface from from any angle....
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    21$$
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    By extension of their logic if I wire up my 15A...

    By extension of their logic if I wire up my 15A circuits with 500kCMil, I get free electricity!
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    I just looked at the manual for a Trane 3 phase...

    I just looked at the manual for a Trane 3 phase unit we have here, it says "Max. Circuit Prot. Device .... 15A". It doesn't distinguish between a CB or fuses. Most commercial units (which is where...
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    2$$
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    In V/Hz there is no inner control loop, that is...

    In V/Hz there is no inner control loop, that is correct. The VFD puts out a V/Hz ratio commensurate with the commanded speed, but has no idea if the motor responded, or in many cases if the motor is...
  20. Thread: Challenger

    by Jraef
    Replies
    2$$
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    238

    Challenger is long gone, although parts of them...

    Challenger is long gone, although parts of them were rolled into Eaton through mergers and acquisitions. You might try an Eaton distributor.
  21. Replies
    38$$
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    It may not be in the NEC, but it's entirely...

    It may not be in the NEC, but it's entirely possible that YOUR FACILITY has a standard, written or not, that they want you to follow so that the next person to open that box does not have to second...
  22. Thread: 3 phase motor

    by Jraef
    Replies
    5$$
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    283

    To expand a bit: 240V is the national standard...

    To expand a bit:

    240V is the national standard for "Distribution Voltage" (ANSI C84.1); meaning what the utility is supposed to supply to the Service Entrance point. Distribution Votlage is...
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    Common sense is however not codified... :angel:

    Common sense is however not codified... :angel:
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    3$$
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    430.122 REQUIRES that conductors feeding a VFD...

    430.122 REQUIRES that conductors feeding a VFD are sized at 125% of the INPUT CURRENT rating of the VFD. There is no allowance for what you have programmed into the VFD, in fact that is the INTENT of...
  25. Thread: Harmonics and PF

    by Jraef
    Replies
    7$$
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    555

    Not AFE drives, an Active Harmonic Filter that...

    Not AFE drives, an Active Harmonic Filter that connects to the distribution panel or MCC bus and injects corrective current which corrects all harmonics up to about the 50th from any source on that...
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