• powder extinguishing system

    Hi All, regarding NFPA 17 what are the minimum density that we can apply for the total flooding (for example a room) and an object ( for example transformer) compare to NF EN 12416-2 that the minimum density is 1.2 k...
    last modified by sammy.kadouri
  • NFPA-496 7.4.10

    How to interpret the power source requirement in NFPA-496 7.4.10 "The electrical power for the positive pressure air system shall be taken off the main power line ahead of any service disconnects to the control room o...
    last modified by chenting.elec
  • NEC Training: What's in it for you?

    When it comes to NEC training, there are almost as many different providers as there are letters on the pages within the Code. What makes one provider stand out compared to the other options? What do they offer that a...
    last modified by dvigstol
  • journey man electrician

    What work can a journey man electrician do? this pertains to work on his/her employers buildings.
    last modified by jack.clark
  • Filling inside the wireway

    The article of NFPA79 clearly state the following:   13.5.2 Percentage fills of Raceways (Ducts) "The combined cross-sectional area of all conductors and cables shall not exceed 50% of the interior cross-section...
    last modified by abderrazak.dabbagui
  • Copper Busbar installation - exposure and corrosion

    In NEC article 300.37, it states that exposed busbar may be installed in areas that are accessible to qualified persons only. Does this imply that this given area must be enclosed or fenced off in some manner? Also, i...
    last modified by mylumbermill
  • NEC EGC Size Compliance for Grounded Systems Power Circuits in Conduits and/or Cable Trays

    EGC sizing for Grounded Systems of ungrounded conductors, multiconductor cable, multiple circuits, and conductors in parallel when installed in conduits or Cable Trays shall comply with NEC Section 250.122 (A), (B), (...
    last modified by manuelparedespe
  • Arc Flash Equipment Labeling Requirements

    Greetings, I am needing some clarification on what appears to be a contradictory statement pertaining to the content of the equipment labeling requirements of NFPA 70E-2015, Article 130.5(C), 130.5(D)(3), and the comm...
    Steve Benton
    last modified by Steve Benton
  • Failure Mode of GFCI

    I disassembled a "failed" GFCI.  (If you've not done so, I strongly encourage it....they are  complex.) There are "springy" metal contacts that open when the GFCI trips.  On both sides (hot and "neutral...
    last modified by mhl24
  • NEC 250.122 (A) and (B) applications and interpretations

    NEC requires to size the EGC by using Table 250.122 as indicated in Section 250.122(A), and add requirements to comply with sections 250.4(A)(5) or (B)(4) for voltage drop consideration and to provide a retu...
    last modified by manuelparedespe
  • Vacuum excavation to expose underground electrical utilities

    We use vacuum excavation to expose underground utilities to precisely locate them.  When using this technique on buried electrical utilities, we are concerned about both arc flash and electrocution if we inadvert...
    last modified by brian.britain
  • IP Rating For Cabinets in Automatic Sprinkler Room.

    What is the minimum IP rating of pump controller cabinets which are to be used in a fire pump room protected with Automatic Sprinkler system as per NFPA. Please note we are proposing a controller cabinet with IP rati...
    last modified by gm@novazen.com
  • Uniterrupted Power System / LSC

    I recently came across an UPS grandfathered in an Ambulatory Surgical Center (ASC)  / endoscopy.   A lightning storm in the area somehow tripped or overloaded the UPS.   The normal power was n...
    last modified by andrea
  • grounding buggy testing

    How often does a grounding buggy need to be  electrically tested (megger). 4.16-13.8 volts
    last modified by jrdelagarza
  • UL 60950 PDU plugging into a UL 1778 UPS

    I know that RPT (Relocatable Power Tap) units (power strips) have to be plugged into a permanent receptacle per this link. NFPA 1:  Electrical Fire Safety and Relocatable Power Taps (power strips), #FireCodeFrid...
    last modified by mburkle
  • MC securing and supporting

    Would like to see if I can get a response from NFPA as per 330.30 (C) Unless otherwise provided, cables shall be supported at intervals not exceeding 1.8m (6ft) Horizontal runs of Type MC cable installed in wooden o...
    last modified by wattsj
  • When is interacting, really interacting?

    So, I'm trying to figure out when to have our folks wear PPE according to NFPA 70E.  For example, if one of my folks (Qualified) is throwing a 480 volt switch on a welder plug; is that interacting or what about t...
    last modified by joseph.ratta@ipaper.com
  • Generator grounding and connecting neutrals

    We have a few 480 volt 3 phase generators that supply emergency power to our sewer pump stations. we do not connect the neutral as we do not us 277 volts. but what do we do with it. ground it? bond it? the generator...
    last modified by dpw252
  • Surge protectors

    In a long term faciltity, when using surge protectors in resident rooms, do they have to be hospital grade?
    last modified by tjski1
  • Free NEC Changes Webinar

    Free Webinar - Proposed Changes to the 2017 Edition of the National Electrical Code Register now for the free NFPA webinar on the proposed changes to the 2017 National Electrical Code® (NEC®). NFPA's Jeff S...
    last modified by seanryan