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Recent content by sigmapsi

  1. sigmapsi

    Isolated phase service entrance conductors

    yes, the requirement was to run PVC underground. there ia an artical in the nec for isolated phase conductors. penetrating the service gear enclosure required cutting sots between the conduit hole cutouts in the enclosure, or removing a square section if I remember correctly.
  2. sigmapsi

    Propane gas sizing

    from what i recall, the tables in nfpa 54 are based on natural gas. the natural gas capacities at various pressures and pipe sizes must be adjusted for specific gravity factors for propane. nfpa 54 has another table of correction factors for specific gravity. sorry i can't recall what the...
  3. sigmapsi

    Isolated Phase service entrance conductors

    The "subconductors" were each 500kcmil. thanks for the info. I guess the utility answer was accurate after all. They also noted a limitation of 25 ft and that conduits had to be PVC so that inductive heating affects would be minimized. Special consultation had to be provided for...
  4. sigmapsi

    Isolated Phase service entrance conductors

    We had a project where the utility required isolated phase construction for a 2500a, 480V service. What they wanted was that the parallel 7 sets of conductors had to be run separated by each phase to the service disconnect. I never heard of this, and had to research the NEC to verify that was...
  5. sigmapsi

    Isolated phase service entrance conductors

    We had a project where the utility required isolated phase construction for a 2500a, 480V service. What they wanted was that the parallel 7 sets of conductors had to be run separated by each phase to the service disconnect. I never heard of this, and had to research the NEC to verify that was...
  6. sigmapsi

    Chilled Water Systems for Building HVAC - Achieving High Temp. Rise

    What about dehumidification? Is there a loss in dehumidification control?<br> <br> I have seen problems with loss of dehumidification control on large chiller systems when the chilled water temperature is reset up only a couple of degrees.<br> <br> I also am wondering how much supply temperature...
  7. sigmapsi

    Intake Air Louvers

    When it comes to light or powdery snow, I do not think there is any louver that can stop all snow entry. The only solution I have been able to work out is to assume it will enter, then pitch the bottom of the duct or plenum to louver or to a drain.

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