• HOA hand switch leg direct to motor starter

       There has been some debate among my coworkers lately about the "Hand" switch leg of a rotary HOA selector switch going directly to the coil of a motor starter. I have been making the case that this i...
    jfosterjrod58
    last modified by jfosterjrod58
  • Wire Color for Remain Energized 24VDC Conductors.

    NFPA79 specifies: 13.2.3.2 The use of other colors for the following applications shall be as follows: (1) WHITE with BLUE stripe for grounded (current-carrying) dc circuit conductor (2) WHITE with ORANGE stripe ...
    borisg
    last modified by borisg
  • NFPA 79 - RACEWAY DENSITY

    NFPA 79 Section 13.5.2 states that "the combined CSA of all conductors and cables shall not exceed 50% of the CSA of the raceway. My question is can this value be greater than 50% if the temperature of the cables in ...
    alan.morrison
    last modified by alan.morrison
  • Equipment Grounding

    In regards to NFPA 79 Chapter 8:   If multiple non-current carrying conductive parts have continuity across them, (i.e. pipe -> equipment frame -> other pipes) can I use their continuity as a ground path o...
    smckinley89
    last modified by smckinley89
  • CAN I USE GND EARTH INSTEAD OF NEUTRAL

    Hi All,   I am making a 3 Phase power meter using a MICROCHIP IC ATM90E36A. They recommend to use neutral wire as a GND reference to measure voltages at 3 hot legs but in my loads (Air Conditioners) there is no ...
    arshdeep
    last modified by arshdeep
  • MTW in Conduit?

    Can MTW wire be ran in conduit or is it strictly to be used for wiring in a panel?   We would be installing the wire between our control panel and motor and running it in conduit.
    marc.gelinas
    last modified by marc.gelinas
  • What would be the proper wire size?

    I have a feeder circuit - power coming into a terminal block rated for 175A then wired to a 50A contactor to a compressor with an RLA of 28.8A.  The terminal block states 75C wire and the compressor states use mi...
    matthew@haskris.com
    last modified by matthew@haskris.com
  • Current-currying conductor in cable

    Hi, in a multiple-conductors cable the load is unbalanced among the conductors: which wires should be considered "current-carrying" conductors?   E.g.: a jacketed cable with 7 identical wires; for the specific ...
    giacomo.gasparini
    last modified by giacomo.gasparini
  • Commercial System Inspector

    Cennox is a nationwide corporation looking for a  Commercial Systems Inspector.   Part- Time in the Cleveland,OH; North Dayton, OH;  Full- Time in Richmond, VA;  Norfolk, VA; St. Louis, MO 
    michelle.dyer
    created by michelle.dyer
  • Electrical luminaire wire colours

    Hi  On an electrical luminaire - outdoor floodlight, could someone please confirm what colour wires are required for use in the US? NFPA 791 states that the correct colour wiring is required but it doesnt say wh...
    laurahazlewood
    last modified by laurahazlewood
  • Main Lug Only Panel Fed From a Delta/Wye Transformer

    I am working in a project for a Utility Substation and I came across a question that perhaps someone in here could help me with.  I am aware that utilities don't have to abide by the NEC-NFPA70 per 90.2.   ...
    rafis
    last modified by rafis
  • Energization of Electrical Equipment On a Set Time Schedule

    Some years ago a worker was completing work on a de-energized transformer.  He was electrocuted before he finished his work.  Very sad incident.   The investigation revealed that the worker tr...
    tvanhooser
    last modified by tvanhooser
  • GFCI required for control panel?

    Is a GFCI outlet required for a computer programming port located thru the door of a control panel? We typically install these for our programmers in order for them to plug in their laptop to program the PLC. NFPA 79...
    troy.smith
    last modified by troy.smith
  • NFPA 99 (6.2.2.6.1 )Clarification Required

    With refer to NFPA 99 Older versions Ref  6.4.2.2.6 Wiring Requirements   6.4.2.2.6.1 Separation from other circuits .The life safety branch and critical branch shall be kept independent of all other wiring...
    vijay.r1986
    last modified by vijay.r1986
  • UL61800-5-1 - terminal block rating

    As a UL61800-5-1 industrial power suppliy manufacturer with 480Vac input and 680Vdc output may I use UL1059 600V rated terminal block for the output DC as the clearances/creepage are conformant to UL 61800-5-1 or shou...
  • Are lockable power switches required for industrial equipmemt that can be unplugged?

    For one-off/custom built pieces of manufacturing equipment that can be simply unplugged before servicing, is it still necessary to have a lockable power switch? My local AHJ says that as long as the switch is within s...
    spuddinator
    created by spuddinator
  • Do 3-phase isolation transformers require secondary fusing?

    We provide a 3-phase isolation transformer (30-47 KVA) with each of the Profile Machining Centers we sell. To meet NFPA 70 and/or NFPA 79, do we need to provide fusing between the isolation transformer secondary and t...
    artcampbell
    created by artcampbell
  • Spaces Around Control Cabinets

    Hi In NFPA 79 clause 11.5 regarding "Spaces Around Control Cabinets and Compartments" refer  to NFPA 70 Article 670. But 670 does not contain any distances. NFPA 79 is a "copy" of IEC 60204-1 and here is distanc...
    torben.jensen
    last modified by torben.jensen
  • Nameplate Data FLC Calculation

    How do you officially calculate full-load current (FLC) for Machine Nameplate Data as outlined by NFPA 79 - Article 16.4.1?   Applying motor current ratings correctly in this calculation seems to be th...
    howe.donald
    created by howe.donald
  • Fire door at Transformer Fire wall

    Hi,   I have a query related to fire door at Transformer Fire wall. Anybody have any experience to provide fire door at Transformer fire wall ? Which code permits fire door at transformer fire wall as escap...
    pratik.bandyopadhyay
    last modified by pratik.bandyopadhyay