• NFPA 70, Article 690.31

    I need assistance with interpretation of the following article.  My contractor is using the following Code exception to omit labeling on PV string wires.  Their logic is that each string wire is is pre-fabri...
    last modified by tasha_mccarter
  • NFPA  70, Art 501.5 (E)

    In NFPA 70, Article 501.5(E), 1 For a Class I Division 2, Terminations - it says cables entering an enclosure required to be explosion proof shall be sealed at the point of entry.   A squirrel cage induction mot...
    last modified by dnowicki
  • Should a floating ground system chassis be connected to Earth Ground? 

    I have a mobile Radar system, with internal generator, mounted on a truck that was designed and built with a floating ground. When the system is removed from the truck and is sitting on the ground, should the system c...
    last modified by anthony.becker
  • Wireway Classified as "Free Air"

    Can a wireway be classified as a "Free Air" environment if there is 125 scfm of airflow through it?
    last modified by rayk
  • Testing of a non-UL certified transfer switch prototype

    Hello all!   I have designed and built an automated battery transfer switch that currently fits into a 70 AMP breaker box. The current setup is home breaker box -> Romex -> device -> Romex -> breaker...
    last modified by jeremiah
  • GFCI requirement for water closet

    With regards to GFCI requirements NEC 210.8. Requirements for water closets are not addressed specifically. (definition: a water closet is a small enclosed area with a door that contains only a toilet. No sinks, tubs,...
    last modified by johnsonb.0671
  • Questions about 120v breakers. 

    I am an electrical novice.   In and industrial setting, is it required by NFPA 70/70E to lockout a 120v standard breaker (like a household breaker), where the breaker has not been designed to take a lock? Is a ...
    last modified by shaney
  • Conduit sealing for increased Safety Enclosure

    in our project, increased Safety (exe) enclosure are installed in class I, zone 2 . As per NPPA 70,  Inarticle 505.16 (C):class II, Zone 2 locations, seals shall be located in accordance with 505.16(C)(1) and (C)...
    last modified by huab2000
  • 2017 NEC 700.3(F) and Fire Pumps

    Do the requirements of the 2017 NEC article 700.3(F) apply to fire pumps?  Fire pumps are mentioned in the code commentary but are not referenced in any other part of article 700.  They are often served from...
    last modified by rbush
  • NFPA 70 Article 314.29 (a)

    So this all started by me speaking out of my ass by telling someone I think the code has a unobstructed distance requirement from the opening of junction boxes, and pulling condulets. They just accepted it, but I deci...
    last modified by c.schutter96
  • NFPA 70 700.16  Egress Lighting

    Hi, My question is in regards to the second paragraph of 700.16 which states:   "Emergency lighting systems shall be designed and installed so that the failure of any individual lighting element, such as the bur...
    last modified by vmazzeffi
  • Luminaires Grid Clips or Screws

    Hello,   My name is Shane Templeman, I recently became a member of the NFPA again. I have been a member before and need this answered. Please let me know if my reading of this article is accurate.   This i...
    last modified by flaggdies
  • Working Space Requirements 110.26(C)(2)

    Hello,    We are a California Electrical Contractor and we installed a new 1200 amp switch gear section for a retail center. This was a upgrade of a existing 1000 amp switch gear section.    We a...
    last modified by corykruip
  • I am trying to apply Table 130.7(C)(15)(A)(a) of NFPA 70e

    I am trying to apply Table 130.7(C)(15)(A)(a) of NFPA 70e to my scenario.  I need to open hinged covers on a control cabinet to reset faults on VFD's occasionally.  These control cabinets usually have 480V c...
    last modified by brian.calvert
  • NEC 250.122B EGC Size

    I am trying to understand what base size we are supposed to use when we need to proportionally increase the size of the Equipment Grounding Conductor (EGC) per NEC 250.122B. Let’s say the following scenario: Bre...
    last modified by rafis
  • 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
  • AFCI protection for mobile homes

    Not sure if this is the correct place for my question but here goes; can anyone help me to understand why AFCI protection (as outlined in 210.12) for dwelling units is not required in manufactured / mobile homes, whic...
    last modified by diverseelectric
  • NEC 250.122(B)

    In regards to NEC 2014 250.122(B). Assume calculations show that a  370 wire sizing ampacity is required for a feeder, and #500 KCMI copper conductor is selected to feed this load from a 400 amp circuit breaker p...
    last modified by dmatern
  • Paralled Conductors-Derate Q

    I have parallel feeders to a 800 Amp MCC in separate raceways from the distribution breaker.  Does the wire have to be derated according to Table 310.15(B)(3)(a) from NFPA 70 code.  We are having a debate on...
    last modified by matt.rudolph

    ELECTRICAL ROOMS - FIRE RATING I'm looking for required fire ratings of Elec Rms in office bldgs, as well as other bldg types. What is the best manual to research: NFPA 101, NFPA 75, or other? Thanks, jksjim
    last modified by jsworks