• NFPA-79 Wire Color Code

    The NFPA-79 Wire Color Code is important for any person to quickly identify Circuits.  Consequences of using the wrong Wire Color could be lethal.   The NEC calls out (3) Colors:      * ...
    last modified by rcramereleceng
  • Electrical Panel Lexan Covering Exposed 480VAC

    I worked for 24 years at General Motors and it was common to see exposed 480VAC in electrical panels covered with Lexan glass to prevent accidental contact. We performed arc flash studies and all of our panels were la...
    last modified by zz3l4b
  • Does the NEC allow for the use of nonmetallic electric conduits in plenum of a confined space in a building?

    The NEC don't allow for the use of nonmetalic electric conduits in plenum (open space above false ceiling used for return air) in order avoid the convey of smoke and/or fire to other parts of the building. Is this ap...
    last modified by abdulazizabuali
  • 480vac 3ph Power Distribution

    I have a system where we are supplying a skid with 3 VFD/motors. The VFD/motors are each wired to there own fused safety disconnect.  The skid also has a fused disconnect for power supply to a 480/120 transformer...
    last modified by marc.gelinas
  • Single motor protection with VFD per Article 430.130

    Looking for interpretation of Article 430.130(A)(1) and (2) with respect to Branch-Circuit Short-Circuit and Ground Fault Protective device rating for single motor applications when a VFD is installed. The article ref...
    last modified by tom.brenner
  • NFPA 79 Inspector needed

    I'm looking for a 3rd party inspector to inspect a machine to NFPA 79 standard in the Wisconsin area.   Any suggestions.
    last modified by mwessel
  • What Is Wrong With This Genset?

    last modified by david.pfau
  • Instrumentation Enclosure Component Fill Volume Requirement?

    Instrumentation Enclosure Component Fill Volume Requirement?   Hello,  I work for what amounts to an industrial supplier and we produce instruments that are composed of various electrical/other components....
    last modified by jtmiller
  • Knowledgeable Person

    Is there a industry excepted definition of a Knowledgeable Person.  I am working on updating my EEWP and we are looking into the approval portion and would like to have a knowledgeable person in this pr...
    last modified by jmerati
  • Surge Protection

    NFPA 79, 7.8.1 States that " SPD's (surge protective device) shall be provided for industrial machinery w/ safety interlock circuits to protect against the effects of overvoltages sue to lightning and switching surges...
    last modified by jeremy.bello@emerson.com
  • Wire Color for Remain Energized 24VDC Conductors.

    NFPA79 specifies: 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 ...
    last modified by borisg
  • Electric Griddle info.

    Hello, my company is promoting a function and we have 4 electric griddles similar to the George foreman type.  I was trying to find information on what gage extension cords are needed spanning a length of 75-100 ...
    last modified by troy.cornett
  • 300va transformer, must the core be grounded

    I have equipment using a 300va custom wound transformer.   The core is lacquered and I have to grind off the coating to ground the frame.     Is it mandatory that the core be grounded and...
  • Door Interlock as par NFPA 79 Clause 6.2.4.

    Hello,   We have separate enclosure where enclosure which contains the supply disconnecting means has mechanical interlock that door can not be open without  making switch OFF. We also have second enclosur...
    last modified by vishal_g_patel
  • 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...
    last modified by jfosterjrod58

    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 ...
    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...
    last modified by smckinley89

    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 ...
    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.
    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...
    last modified by matthew@haskris.com